Context: Increasing the amount of water that may enter the soil in a given period of time: Residue cover and a rough soil surface will increase the infiltration rate. Compaction of the soil surface, lack of residue and poor choice of tillage practice will decrease infiltration. Steeper slopes, wheel tracks, and rows run up and down hillsides increase runoff rates if the water dies not infiltrate. Infiltration rate decreases with increased time of wetting. Therefore, the amount of water applied each irrigation will affect the fraction of the water that enters the soil and the fraction that will runoff. Small pockets and depres- sions in the soil surface will hold a volume of water at that location, until the soil surface can receive the water. Midseason cultivation or in-row soil surface modification (i.e. dammer/diker) will increase the surface storage.

Question: what will midseason cultivation or in-row soil surface modifications such as dammers or dikers increase?

Answer: the surface storage

Kelley, L. (2014a). Irrigation Fact Sheet #7- Reducing and Evaluating Irrigation Runoff.Instantaneous irrigation application rates compared to soil infiltration rates. https://www.canr.msu.edu/uploads/235/67987/FactSheets/7_ReducingAndEvalRunoff.pdf


Context: Flow meters are mechanisms installed in or on the main distribution pipe of the water supply. The actual flow is measured by impeller or sonar. Flow meters have the advantage of simplicity as meters and can be read monthly and recorded. The disadvantage to flow meters is cost and maintenance. To maintain accuracy meters need to be calibrated at least annually. Meters need to be installed in a straight section of pipe at a point in the transport pipe where all of the water used must pass.

Question: what should be done to maintain accuracy of the flow meter?

Answer: calibrated

Kelley, L. (2014a). Irrigation Fact Sheet #7- Reducing and Evaluating Irrigation Runoff.Instantaneous irrigation application rates compared to soil infiltration rates. https://www.canr.msu.edu/uploads/235/67987/FactSheets/7_ReducingAndEvalRunoff.pdf


Context: Estimating Water Use: Conducted correctly, any combination of these systems could produce estimates that meet the requirements of the law. Producers need to evaluate their water use and devise a simple, low-cost, low-time input method to accomplish the goal of the legislation that may improve the management of the operation. Many farm supply houses, greenhouse supply houses and irrigation supply houses carry flow meters and run time timers.

Question: To estimate their water use what should producers do?

Answer: evaluate their water use

Answer: devise a simple, low-cost, low-time input method to accomplish the goal

May, J. (2013). Water Use Report Requirements for Swine Operations. http://www.michigan.gov/mda


Context: Increasing the amount of water that may enter the soil in a given period of time: Residue cover and rough soil surfaces will increase the amount of water that may enter the soil in a given time period. Compaction of the soil surface and increased slopes, hillside or row contours, will decrease the amount of water that may enter the soil in a given period of time.

Question: what will decrease the amount of water that may enter the soil in a given time period?

Answer: Compaction of the soil surface

Answer: increased slopes

Answer: hillside or row contours

Kelley, L. (2014a). Irrigation Fact Sheet #7- Reducing and Evaluating Irrigation Runoff.Instantaneous irrigation application rates compared to soil infiltration rates. https://www.canr.msu.edu/uploads/235/67987/FactSheets/7_ReducingAndEvalRunoff.pdf


Context: Increasing the amount of water that may enter the soil in a given period of time: Calculating instantaneous irrigation application rate is part of the planning process for new irrigation systems. For a given application, the instantaneous irrigation application rate is the amount of time from the first drop of water landing at a point in the field, to the last water hitting the point. This calculation is often adjusted to minutes for a one-inch application of water.

Question: what is the instantaneous irrigation application rate for a given application?

Answer: the amount of time from the first drop of water landing at a point in the field, to the last water hitting the point

Kelley, L. (2014a). Irrigation Fact Sheet #7- Reducing and Evaluating Irrigation Runoff.Instantaneous irrigation application rates compared to soil infiltration rates. https://www.canr.msu.edu/uploads/235/67987/FactSheets/7_ReducingAndEvalRunoff.pdf


Context: (2) Ground water availability. Irrigation is not profitable without a reliable and adequate source of water. Nearby large volume irrigation, municipal or industrial wells are an excellent source of water availability. Well drillers familiar with large volume wells in your area are also excellent resources. Michigan has available groundwater mapping tools that can help evaluate potential water withdrawal sites.

Question: who are excellent resources to help in identifying adequate sources of water?

Answer: Well drillers familiar with large volume wells in your area

Kelley, L. (2013). Irrigation Fact Sheet #12 - Nitrogen Application with Irrigation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/12_NitrogenApplicationWithIrrigationFact_Sheet.pdf


Context: Both acts use the same definition for a "large capacity well". Large capacity wells are those with the capacity to withdraw 100000 gallons per day (70 gal/min) on average in any consecutive 30-day period. The combined capacity of more than one well at a site that is 100000 gallons or greater capacity/day (70 gal/min), also meets the large capacity well definition. Water use reporting also includes surface water withdrawals with single or combined capacity at a site of 100000 gal/day (70 gal/min) on average, in any consecutive 30-day period. All agricultural water uses (irrigation, cooling, animal watering, etc.) will apply to these laws. Well pumping capacity is included in the well log that should have been filed if the well was drilled after 1968 and are generally available at the local health department, from well drillers or at the MDEQ website.

Question: Where can the well log be found?

Answer: local health department

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: (3) Surface water availability. Is surface water available in dependable large volumes? Surface water quantities need to be available at the time of maximum irrigation, often late July early August. This is the season the surface waters are near their lowest. Make sure to evaluate available flow the summer before you start irrigating. In most areas you may not delete stream flow to the extent that it negatively impacts neighbors or the environment. If not, consider part of the water of the States, drainage ditches flow, may be depleted. Remember there can be major contamination challenges impacting food safety in using surface water for vegetable irrigation and cooling.

Question: when should an irrigator evaluate available flow to determine surface water quantities?

Answer: the summer before you start irrigating

Kelley, L. (2022). Irrigation Fact Sheet #11- Checklist for Planning Irrigation Systems. https://www.canr.msu.edu/irrigation/upoads/files/11ChecklistForPlanningIrrigationSystems08.22.pdf


Context: Instructions for completing the Evaluating Potential Irrigation Runoff form. 3. Set the machine for an irrigation amount (timer setting, system speed or run time) typically used and run the machine across the identified area. Record the system settings. 4. Center Pivots - Starting at the pivot point and progressing to the furthest reaches of the machine, pace or measure 50 feet increments along that line to identify observation points, or identify three equally space observation points under each span. Solid set or travelers - Starting at one edge of the wetted area and progressing to opposite side, pace or measure 50 feet increments along that line to identify observation points.

Question: what are the third and fourth instructions for completing the Evaluating Potential Irrigation Runoff form?

Answer: 3. Set the machine for an irrigation amount (timer setting, system speed or run time) typically used and run the machine across the identified area. Record the system settings. 4. Center Pivots - Starting at the pivot point and progressing to the furthest reaches of the machine, pace or measure 50 feet increments along that line to identify observation points, or identify three equally space observation points under each span. Solid set or travelers - Starting at one edge of the wetted area and progressing to opposite side, pace or measure 50 feet increments along that line to identify observation points

Kelley, L. (2014b). Irrigation Fact Sheet #13 - Reducing and Evaluating Irrigation Runoff. https://www.canr.msu.edu/uploads/236/43605/FactSheets/13_ReducingAndEvaluatingIrrigationRunoff_5-9-14.pdf


Context: If a producer has a site that exceeds the 70 gal/min threshold capacity, then they are responsible for collecting monthly water use data to file the annual water use reporting forms from 2004 and after. Reports are due April 1st from the previous year. Paper copies of water use reporting forms (when available from the State) will be available from most MSU Extension and USDA Farm Service Centers.

Question: who should collect monthly water use data if a site exceeds the 70 gal/min capacity threshold?

Answer: producer

Kelley, L. (2009a). Irrigation Fact Sheet #8 - How to Get More from your Irrigation System. https://www.canr.msu.edu/uploads/235/67987/lyndon/HGMIrrSys.pdf


Context: Permanent improvements. A repayment schedule may be included in the agreement for the recovery of investment dollars not recouped if early termination of the agreement is required. An annual cost of permanent improvements to the land needed for irrigation can be found by amortizing the dollar investment over the period of the contract at the current interest rate. The annual cost may be added to the dry land rent rate plus an additional opportunity cost representing the added income opportunity with irrigation to compensate landowner for permanent improvements to the land needed for irrigation.

Question: to find the cost of improvements what should annual cost be added to?

Answer: dry land rent rate plus an additional opportunity cost representing the added income opportunity with irrigation to compensate landowner for permanent improvements to the land needed for irrigation

Kelley, L. (2009a). Irrigation Fact Sheet #6 - Irrigation Aspects of Land Lease Agreements. https://www.canr.msu.edu/uploads/235/67987/lyndon/LandRent.pdf


Context: The infiltration rate is the rate water can enter the soil surface. Michigan soils have infiltration rates from a high of 1 inch/2 hour to, as little as 20 minutes per inch. Heavier soils such as clay and clay loam will take water in at a slower rate than sands and sandy loams. Tillage method and surface compaction since a tillage operation affects infiltration rate. Conservation tillage and no-till result in the highest infiltration rate while disc and moldboard tillage result in the lowest rates, particularly after several wetting events. Estimates for water infiltration rates are included in the "physical and chemical properties of soils" section of the soil survey for your county.

Question: where can estimates for water infiltration rates be found?

Answer: included in the "physical and chemical properties of soils" section of the soil survey for your county

Kelley, L. (2014b). Irrigation Fact Sheet #13 - Reducing and Evaluating Irrigation Runoff. https://www.canr.msu.edu/uploads/236/43605/FactSheets/13_ReducingAndEvaluatingIrrigationRunoff_5-9-14.pdf


Context: (4) Water rights and regulation. Make sure you understand your rights and obligation to use water in your State. Example: Michigan operates as a riparian state for surface water use allowing only the property with legal description adjacent to the surface water to receive the water, but well water may be transferred between properties.

Question: what should an irrigator understand to use water in their state?

Answer: your rights and obligation

Kelley, L. (2022). Irrigation Fact Sheet #11- Checklist for Planning Irrigation Systems. https://www.canr.msu.edu/irrigation/upoads/files/11ChecklistForPlanningIrrigationSystems08.22.pdf


Question: To be considered a large capacity well what is the withdrawing capacity in a consecutive 30-day period?

Answer: 100000 gallons per day (70 gal/min)

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: Land rent pricing: Establishment of irrigated rental value is relatively straight forward when all of the irrigation equipment and water supply is the landowners. Average current rent value is available from State and Federal Agricultural Statistic Services or your Agricultural Economics Department from your States Extension service. Talking to neighbors that rent irrigated land is one of the best ways to get a feel for irrigated rental value. Land rent auction can also be used to establish rent value but a solid structure for the process is necessary.

Question: what is the best way to get an understanding of irrigated land rental value?

Answer: Talking to neighbors that rent irrigated land

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: There are tremendous differences in cost of establishing irrigation. Several factors can lead to low water source cost (less than $15000). Factors leading to high water source cost (greater than $50000) are the reciprocal of what is listed:.(a) productive water tables are close to the surface (less than 40 feet). (b) riparian rights to a dependable surface water option adjacent to field. (c) ample three phase electric power is readily available near the pumping site. (d) system is designed for moderate to low pumping pressure. (e) Hills and Steep slopes may require higher pressures and large wetted areas to reduce chance of run-off.

Question: what is common in the cost of establishing irrigation?

Answer: tremendous differences

MSU Extension. (2024). Irrigation Costs - Irrigation. https://www.canr.msu.edu/irrigation/Irrigation-Planning-/irrigation-costs


Context: Estimating annual irrigation costs: Annual irrigation costs can be divided into two categories: annual cost of ownership and the annual cost of operation - mainly the cost of energy and labor. The annual cost of ownership is often estimated by the DIRTI (Depreciation, Interest, Repairs, Taxes, and Insurance) formula which spreads the actual cost of ownership of an equipment investment over its usable lifespan or investment period. A standard procedure is outlined on page 4 of MSU Extension Bulletin E-2131, "Custom Work Rates in Michigan". This formula can provide you with the annual cost of the original investment in equipment and improvements.

Question: what does the DIRTI formula do?

Answer: spreads the actual cost of ownership of an equipment investment over its usable lifespan or investment period

Kelley, L. (2007b). Irrigation Fact Sheet #5 - Estimating Annual Irrigation Costs. https://www.canr.msu.edu/uploads/235/67987/irrigation_costs/5_Estimating_Annual_Irrigation_Costs.pdf


Context: (2) The MSU Soil Water Balance Sheet: is a paper version of a checkbook scheduler producers can use Reference Evapotranspiration (E.T.) Data from their own E.T. gauge station or Reference E.T. data form Purdue's PAC center weather stations. For Michigan, producers can use the Enviroweather data listed above. The Soil Water Balance Sheet helps producers convert the Reference E.T. into a estimate water removal for either corn or soybeans in their field.

Question: what evapotranspiration data is available for producers to reference?

Answer: Data from their own E.T. gauge station or Reference E.T. data form Purdue's PAC center weather stations

Answer: Data from their own E.T. gauge station

Answer: Reference E.T. data form Purdue's PAC center weather stations

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: (12) Specialty/vegetable crop options. Indiana and Michigan's irrigated land is dominated by contracted specialty crops like vegetable and hybrid seed corn production. The reduced risks offered by sandy soils for early planting, less delays after rain for field work, low to no flooding injury potential coupled with the removal of drought stress entice the high dollar invested seed and vegetable crops to the area. These options and conditions are not available everywhere in Michigan and Indiana. Avoid the idea that "if you build it they will come". Do your homework and identify what options are realistically available and feasible for your operation.

Question: are good growing conditions for high dollar seed and vegetable crops everywhere in Michigan and Indiana?

Answer: not available everywhere in Michigan and Indiana

Kelley, L. (2009a). Irrigation Fact Sheet #6 - Irrigation Aspects of Land Lease Agreements. https://www.canr.msu.edu/uploads/235/67987/lyndon/LandRent.pdf


Context: P.A. 33 of 2006 amended Michigan's Natural Resources Protection Act as part 327 of 451. Changes included: (b2) From the legal perspective, the Baseline Capacity is the reported system capacity used or developed to make a withdrawal on or before Feb. 28, 2006. If a large capacity water user does not report a "Baseline Capacity", MDA will use the highest annual amount of water withdrawn as reported for 2004 or 2005 and calculate one. Note: Since few producers run pumps continuously, most water users have available system capacities which will greatly exceed the amount of water that has been reported in 2004 or 2005.

Question: do water users have system capacities?

Answer: most water users have available system capacities

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: P.A. 33 of 2006 amended Michigan's Natural Resources Protection Act as part 327 of 451. Changes included:  (c) Requirement for new agricultural withdrawals: Both new wells and surface water withdrawal capable of 100000 gallon per day (70 gpm) are now required to register with Michigan Department of Agriculture prior to beginning to pump. Forms are available at the same locations as the reporting forms. You will need to provide the latitude and longitude for the location, an estimate of expected water use by the month and an estimate of the volume of consumptive use of the water pumped. Since most water pumped for irrigation ultimately goes to the evapotransporation of the crop the consumptive use is estimated to be high or about 90%. Water use for harvest cooling is mostly retuned back to surface or groundwater so the consumptive use is estimated to be low about 5 to 10%.

Question: what's the consumptive use estimated as for evapotranspiration of crops?

Answer: high or about 90%

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: Large capacity water users are required to report the following: (a) The amount and rate of water withdrawn on a monthly basis in either gallons or acre inches. (b) The type of crop irrigated if applicable. (c) The acreage of each irrigated crop if applicable. (d) The sources of the water supply. (e) If the water withdrawn is not used entirely for irrigation, the uses of the water being withdrawn. (f) If the source of water withdrawn is groundwater, the static water level of the aquifers need to be determined and reported. (g) Applicable water conservation practices and an implementation plan for those practices.

Question: what are large capacity water users required to report?

Answer: (g) Applicable water conservation practices and an implementation plan for those practices

Answer: (a) The amount and rate of water withdrawn on a monthly basis

Answer: (d) The sources of the water supply

Kelley, L., Miller, S., & Loudon, T. (2006). Irrigation Fact Sheet #1- Agricultural Water Use Reporting for 2006 Changes in Water Use Regulation. https://www.canr.msu.edu/uploads/235/67987/FactSheets/1_AgWaterUseReporting11-29-06.pdf


Context: (5) Water registration. Irrigation water use almost always is considered a large volume water use (capacity to pump > 70 gal./min). In both Indiana and Michigan new installations require a registration. In Indiana this is handled by Indiana DNR. In Michigan you will need to work through the Michigan Water Withdrawal Assessment Tool to determine if your proposed water use is likely to cause a negative environmental impact. At the end of the process you will either be able to register online or may be required to request a site specific review by MDEQ. MDEQ site specific reviews may result in allocation of the water resulting in registration or the opportunity to bring together all large volume water users in the watershed to negotiate reducing use by existing water users to allow allocations for a new water use.

Question: After using the Michigan Water Withdrawal Assessment Tool to determine if an irrigators withdrawal will result in a negative environmental impact what will an irrigator be able to do?

Answer: register online or may be required to request a site specific review by MDEQ

Kelley, L. (2022). Irrigation Fact Sheet #11- Checklist for Planning Irrigation Systems. https://www.canr.msu.edu/irrigation/upoads/files/11ChecklistForPlanningIrrigationSystems08


Context: Checklist for Planning Irrigation Systems: (1) Irrigation water requirements (2) Ground water availability (3) Surface water availability (4) Water rights and regulation (5) Water registration (6) Options for sharing irrigation equipment (7) Map your irrigation ideas  (8) Power sources  (9) Get multiple bids (10) Irrigation economics (11) Crop rotation and tillage preferences (12) Specialty/vegetable crop options (13) Match your farming/family goals to your irrigation ideas

Question: what should be included on a checklist for planning an irrigation system?

Answer: (1) Irrigation water requirements (2) Ground water availability (3) Surface water availability (4) Water rights and regulation (5) Water registration (6) Options for sharing irrigation equipment (7) Map your irrigation ideas  (8) Power sources  (9) Get multiple bids (10) Irrigation economics (11) Crop rotation and tillage preferences (12) Specialty/vegetable crop options (13) Match your farming/family goals to your irrigation ideas

Kelley, L. (2022). Irrigation Fact Sheet #11- Checklist for Planning Irrigation Systems. https://www.canr.msu.edu/irrigation/upoads/files/11ChecklistForPlanningIrrigationSystems08


Context: (3) On and after July 9, 2009 ' Large quantity water withdrawals proposed after July 8, 2009 must receive a favorable assessment from 'Michigan's Water Withdrawal Assessment Tool' or an approval from a requested site-specific review by the MDEQ and be registered before proceeding. If a site-specific review by the MDEQ or an evaluation by the Water Withdrawal Assessment Tool determines that a proposed withdrawal is a zone A or a zone B withdrawal, there is a rebuttable presumption that the withdrawal, as specified in the review or tool, will not cause an adverse resource impact. As previously stated penalties are in place for causing an adverse resource impact.

Question: If an evaluation by the Water Withdrawal Assessment Tool determines a proposed withdrawal is a zone A or zone B withdrawal what is a reputable presumption that can be made?

Answer: will not cause an adverse resource impact.

Kelley, L. (2007b). Irrigation Fact Sheet #4 - Michigan Registration for New Agricultural Withdrawals. https://www.canr.msu.edu/uploads/235/67987/lyndon/MIRegNewAgWith.pdf


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2018, out of 50 reports, 40% were ranked good, 18% were fair, 16% were wet late, 12% were wet early, 10% were wet all season, and 4% were very wet all season.

Question: In 2018 out of 50 reports, what percentage of Nebraska fields were ranked fair?

Answer: 18%

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: May and June are particularly vulnerable times for nitrate leaching in our irrigated fields because of several factors. First, the fields are left fairly wet from last season's irrigation, precipitation from October through May usually puts more water into the soil than it can hold, the crop is still small and not using much water, and most - if not all - the nitrogen for the corn crop has been applied.

Question: what is one contributing factor that leads to irrigated fields in Nebraska being more vulnerable to nitrate leaching in May and June?

Answer: the fields are left fairly wet from last season's irrigation

Answer: precipitation from October through May usually puts more water into the soil than it can hold

Answer: the crop is still small and not using much water,

Answer: most - if not all - the nitrogen for the corn crop has been applied

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: The key to knowing the correct setting for the chemigation pump is to determine how many acres per hour the pivot will cover at the desired irrigation application depth or rate. Chemigation injection pumps are calibrated in gallons per hour (gph). So, if you know how much product you want to apply per acre -e.g., 10 gallons/acre - and how many acres the pivot will irrigate per hour - e.g., five acres/hour - then you will know how many gallons per hour the pump will need to deliver.

Question: if you know how much product you want to apply per acre and how many acres the pivot will irrigate per hour what value can you calculate?

Answer: how many gallons per hour the pump will need to deliver

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Corn R2 crop stage, the stage of growth is known as blister, the approximate days to maturity is 45, and the water use to maturity is 10.5 inches. For Corn R4 crop stage, the stage of growth is known as dough, the approximate days to maturity is 34, and the water use to maturity is 7.5 inches. For Corn R4.7 crop stage, the stage of growth is known as beginning dent, the approximate days to maturity is 24, and the water use to maturity is 5.0 inches. For Corn R5 crop stage, the stage of growth is known as 1/4 milk line, the approximate days to maturity is 19, and the water use to maturity is 3.75 inches. For Corn R5 crop stage, the stage of growth is known as 1/2 milk line - full dent, the approximate days to maturity is 13, and the water use to maturity is 2.25 inches. For Corn R5 crop stage, the stage of growth is known as 13/4 milk line, the approximate days to maturity is 7, and the water use to maturity is 1.0 inches. For Corn R6 crop stage, the stage of growth is known as physiological maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate days to maturity for corn in the R4.7 crop stage, the stage of growth that is known as beginning dent?

Answer: 24

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2021, out of 53 reports, 57% were ranked good, 6% were fair, 6% were wet late, 25% were wet early, 4% were wet all season, and 4% were very wet all season.

Question: In 2021 out of 53 reports, what percentage of Nebraska fields were ranked fair?

Answer: 6%

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Question: In 2018 out of 50 reports, what percentage of Nebraska fields were considered very wet all season?

Answer: 4%

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: The data does not give any insight into why so many farmers over-irrigate late in the year, but it could be because the irrigation routine is set in July when the plants are transpiring at their peak, the days are long and the temperatures are high. Then, as the daylight hours shorten and the temperatures get cooler in late summer, many keep irrigating at July levels even though crop water use for corn has gone from an average of two inches/week at silking to 1.25 inches/week at full dent. Again, as creatures of habit, without good soil water monitoring data to direct our irrigation scheduling, we just keep on doing what we have been doing. Other crops, including soybeans, have a similar dramatic drop in crop water use moving through August and into September.

Question: why do irrigators over-irrigate late in the year?

Answer: it could be because the irrigation routine is set in July when the plants are transpiring at their peak, the days are long and the temperatures are high

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Nebraska is a groundwater-rich state, thanks in part to the High Plains Aquifer. Many people are familiar with the High Plains Aquifer (also sometimes called the Ogallala aquifer), but fewer people know that there are other aquifers in the state. In fact, Nebraska has seven secondary aquifers, which are much smaller in areal extent than the High Plains Aquifer and generally have poorer water quality, but are nonetheless important in places where the High Plains Aquifer and shallow sand gravel deposits are absent.

Question: how many secondary aquifers are present in the state of Nebraska?

Answer: seven

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The analysis focused on dividing the fields into one of six categories based on the soil water levels in the heart of the season (July and August) and on Sept. 15. The six categories were developed based on the readings from the Watermark sensors. The sensors generate data reported in centibars and have a range from 0 (wet) to 240 (dryer) centibars (cb). Centibar is a unit of measure that refers to the force required by the plant to pull the water out of the soil and into the plant. Typically, installations use a set of three sensors, with one sensor installed at six to 12 inches, one at 18-24 inches, and one at 30-36 inches.

Question: if three sensors are typically installed how deep is the first sensor?

Answer: six to 12 inches

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Question: what is the approximate water use to maturity for corn in the R5 crop stage, the stage of growth that is known as 1/4 milk line?

Answer: 3.75 inches

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Different methods can be used to determine how many gallons/hour (gph) the chemigation injection pump should be set to inject. We are going to talk about two of them today. The first one is using the 'speed chart' (water application depth per pass chart) in the 'sprinkler chart' for the pivot or looking up circle time on the computer panel or the pivot app. The second one involves calculating the chemical injection rate using a spreadsheet. This method gives you more details about the system and is still easy to figure. You will just need to enter the basic information for the pivot. If you are interested, download the spreadsheet from UNL Water.

Question: which method that is used to determine how many gallons/hr (gph) the chemigation injection pump should be set to gives more details about the system?

Answer: calculating the chemical injection rate using a spreadsheet

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Grain Sorghum stage 6 crop stage, the stage of growth is known as half bloom, the approximate days to maturity is 34, and the water use to maturity is 9.0 inches. For Grain Sorghum stage 7 crop stage, the stage of growth is known as soft dough, the approximate days to maturity is 23, and the water use to maturity is 5.0 inches. For Grain Sorghum stage 8 crop stage, the stage of growth is known as hard dough, the approximate days to maturity is 12, and the water use to maturity is 2.0 inches. For Grain Sorghum stage 9 crop stage, the stage of growth is known as physiological maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate days to maturity for grain sorghum in the stage 8 crop stage, the stage of growth that is known as hard dough?

Answer: 12

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Overall, our results indicate that an electric motor running at a constant 1770 rpm will use excess energy for much of the center pivot revolution. VFD operation includes the installation of a pressure sensor somewhere on the system. The controller part of the VFD adjusts the motor speed to maintain a set pipeline pressure wherever the sensor is positioned. Some sensors are placed at the pump outlet, but if the irrigated area has a lot of topography, that position is often the worst location for the sensor.

Question: what is the abbreviation for rotations per minute?

Answer: rpm

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Soil water monitoring data is easier to analyze once the crop has taken up water at the 16- to 24-inch depth during the vegetative growth stage. This drier zone can then be monitored with sensors to see if the area gets wetter or drier. If it keeps getting drier, the irrigation system needs to keep running. However, if it starts to get wetter, then stop irrigating for a few days. Ideally, the drier zone should slowly expand deeper with the crop using most of the subsoil water by the time the crop matures. For more information on this scheduling strategy, watch the Advanced Irrigation Scheduling Techniques video.

Question: when does soil water data become easier to analyze?

Answer: once the crop has taken up water at the 16- to 24-inch depth during the vegetative growth stage

Yonts, C. D., Lyon, D. J., Harveson, R. M., Hergert, G. W., Hein, G. L., & Santra, D. (2009). Producing Irrigated Winter Wheat. https://extensionpubs.unl.edu/publication/ec731/pdf/view/ec731-2009.pdf


Context: These six categories were determined because the soil water level where deep percolation losses of water and nutrients slows to a low rate in a silt loam soil is about 70 cb; thus, it is recommended to keep at least one of the sensors in the second or third foot in this range or dryer. Yield losses would not be expected until all the sensors were approaching 140 cb, making the 70 cb level very achievable without any chance of causing yield loss. Field capacity in a silt loam is about 30 cb, so the goal is not to refill the soil above this level with irrigation in the second or third foot.

Question: how many sensors are recommended to be kept in the second or third foot or dryer?

Answer: at least one

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2019, out of 15 reports, 20% were ranked good, 7% were fair, 40% were wet late, 7% were wet early, 0% were wet all season, and 27% were very wet all season.

Question: In 2019 out of 15 reports, what percentage of Nebraska fields were considered wet all season?

Answer: 0%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: A review of soil water data logs from farmers in the Upper Big Blue Natural Resources District indicates irrigators tend to overwater more in wetter years than dry ones. On very dry years like 2022, many farmers apply about the right amount of water. However, some still over irrigate, and some tend to under-irrigate.

Question: what do the soil water data logs from farmers in the Upper Big Blue Natural Resources District indicate about the amount of irrigation farmers apply in wet and dry years?

Answer: irrigators tend to overwater more in wetter years than dry ones

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Nitrate leaching loss rates typically range from five to 10 pounds of nitrogen for every inch of water lost to deep percolation or drainage in Nebraska (based on in-field research as well as modeling nitrate-nitrogen losses in a Hastings silt loam soil series with over-irrigation during May and June. Source Aaron Daigh, 2023). Leaching losses can be even larger in sandy soil, with values as large as 30 lb/ac for every inch of over-irrigation measured in a loamy sand soil. Over-irrigation is very expensive and something that needs to be avoided.

Question: what do nitrate leaching loss rates typically range from in Nebraska in silt loam soils that are over irrigated during May and June?

Answer: five to 10 pounds of nitrogen for every inch of water lost to deep percolation or drainage

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Applying nitrogen fertilizer or crop protection products through a center pivot is an efficient and effective method. In fact, it is a well-documented best management practice to apply nitrogen fertilizer as close to the time the corn will use it to get the most efficient use of the fertilizer. Most of the products are injected into the pivot with a fixed rate injection pump. So, how does one figure the pumping rate to set the pump at, and what about the change the end gun causes when it's turned on and off? We will discuss both challenges in this article.

Question: what are two examples of substances that can be applied through a center pivot that is efficient and effective?

Answer: nitrogen fertilizer or crop protection products

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: More information about how to assemble and prepare Watermark sensors is available in the following video, https://www.youtube.com/watch?v=jpEsjVO497A. Also, for more tips on sensor installation, please review the following CropWatch article, Irrigation Sensor Installation Tips.

Question: where is more information available on how to assemble and set up watermark sensors?

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: However, the winter and spring of 2022-23 has been an exception for most of Nebraska, with off-season precipitation well below normal. This has highlighted the only downside to leaving the soil dry at the end of the irrigation season: In years when we have a very dry off-season, we will need to pump some water in June to refill the profile before the high water demand days of July arrive. The data showed that some fields were at field capacity at the end of the irrigation season in 2022, but many of the silt loam soil fields would require four to five inches of water to refill the profile. The problem is, without soil water monitoring equipment, one will not know if their field is already refilled to field capacity or not. Other lighter soil texture fields will take less water to refill them.

Question: what soil texture fields will take less water to refill their soil profile than silt loam soil fields?

Answer: lighter

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Chadron wells average about 350 feet deep, and the majority (64%) are used for domestic supply, but livestock and irrigation wells account for 15% and 12% of the wells, respectively. The biggest challenge to using the Chadron aquifer is poor water quality.

Question: what percentage of wells in the Chadron aquifer are used to supply livestock?

Answer: 15%

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Using the 40% recommendation, the data shows many irrigators are applying more water late in the season than is needed. Some years, a significant rain can cause the soil to be wetter in September, but it is usually due to applying more irrigation water than needed. The data shows that in 2017, 72% of fields were over-irrigated late in the season, and even in the drought year of 2022, 36% of fields were over-irrigated late in the year.

Question: in the drought year of 2022 what percentage of fields were over irrigated?

Answer: 36%

Melvin, S. (2023b). Optimize Those Last Few Irrigations | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/optimize-those-last-few-irrigations


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For fine sands, the available water in 1 foot of soil at 100% of available water is 1.0 in/ft, the available water in top 4 feet at 100% of available water is 4.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 1.6 in/ft. For loamy sands, the available water in 1 foot of soil at 100% of available water is 1.1 in/ft, the available water in top 4 feet at 100% of available water is 4.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 1.8 in/ft. For sandy loams, the available water in 1 foot of soil at 100% of available water is 1.4 in/ft, the available water in top 4 feet at 100% of available water is 5.6 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.2 in/ft.

Question: what is the minimum balance for water in the top 4ft of fine sand soil at 40% of available water?

Answer: 1.6 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Thus, the pivot should operate at a 90% timer setting when the end gun is off and slow to 77.4% when it is on to apply the 30 lbs/acre nitrogen both when the end gun is off, as well as when it is on. The water application will be different - 0.29 inches when the end gun is off and about 0.33 inches when it is on - but the nitrogen rate will remain the same with the constant injection rate pump. The concept behind this method is that the pivot will irrigate the same number of acres per hour, thus the lower cost fixed-rate injection pump will work correctly.

Question: what should the timer setting of the pivot irrigation system be operating at to apply 30 lbs/acre nitrogen when the end gun is off?

Answer: 90%

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Soil Sensor Install Tips: While other tasks may seem more pressing, early installation of sensors is critical to ensure their proper operation during the later critical growth phases. Early installation helps to minimize root damage, allows time for sensors to acclimate to read actual soil water conditions instead of water within the sensor or slurry, and gives a better chance for proper soil contact.

Question: what does the early installation of soil sensors help minimize?

Answer: root damage

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: To learn more about the secondary aquifers of Nebraska, download the Conservation and Survey Division publication titled 'An Overview of Secondary Aquifers in Nebraska' available at http://digitalcommons.unl.edu/conservationsurvey/138. Questions regarding western Nebraska aquifers may be directed to xxxxx xxxxxx atxxxxxxxxxxxxx; questions regarding eastern Nebraska aquifers may be directed to xxxx xxxxxx atxxxxxxxxxxxxx.

Question: what can be downloaded to learn more about the secondary aquifers of Nebraska?

Answer: the Conservation and Survey Division publication titled 'An Overview of Secondary Aquifers in Nebraska'

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Many irrigators apply more water than necessary toward the end of the irrigation season because the crop is using less water per day. The crop is getting more mature and the days are getting shorter and cooler. The average crop water use rate drops from around 2.1 inches per week at silking to only about 1.2 inches per week by the full dent stage. This 40% reduction requires irrigators to adjust their thinking about how much water needs to be applied each week.

Question: what is the average crop water use reduction percentage between the silking stage and the full dent stage of a crop?

Answer: 40%

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Other secondary aquifers in eastern Nebraska include the Niobrara aquifer (230 wells, mostly in Cedar County), the Codell aquifer (70 wells in Knox and Boyd counties), and the Western Interior Plains Aquifer System. Only one active well is currently installed in the Western Interior Plains Aquifer System in Nebraska, but the aquifer system was a historic source of water to the Omaha area, and still supplies huge volumes of water to Iowa and other states to our east.

Question: how many active wells are in the Western Interior Plains Aquifer System?

Answer: one

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: The description of a zone or nozzle control VRI system is that the sprinklers are pulsed on and off and pivot speed may vary and that irrigation management zones may be any shape or size. Considerations for this VRI system are that has greatest flexibility in application, it is more expensive, and may require additional maintenance and management effort. Example uses include avoiding application on irregularly- shaped uncropped areas for water surfaces. It can also vary irrigation on irregularly- shaped management zones as needed to maximize yield and profits.

Question: what are some example uses of zone or nozzle control VRI systems?

Answer: avoiding application on irregularly- shaped uncropped areas for water surfaces

Barker, J. B. (2017). Considerations in Adopting Variable Rate Irrigation for Center Pivots and Lateral Systems. http://extensionpublications.unl.edu/assets/pdf/ec2000.pdf


Context: Once the system is up to pressure it is a good idea to check the system for leaks and operation of the sprinklers.  If you find missing or inoperable sprinklers refer to the sprinkler chart that was developed for the system to find the correct replacement.  If the system is on rolling or hilly terrain, regulators are also needed for uniform application and definitely should be checked.

Question: what should are also needed if the system is on rolling or hilly terrain and should defiantly be checked ?

Answer: regulators are also needed for uniform application

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2018, 58% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 58% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 47% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 25-36 inch zone became wetter from August to Sept. 15 in 2018?

Answer: 58%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Overall, our results indicate that an electric motor running at a constant 1770 rpm will use excess energy for much of the center pivot revolution. VFD operation includes the installation of a pressure sensor somewhere on the system. The controller part of the VFD adjusts the motor speed to maintain a set pipeline pressure wherever the sensor is positioned. Some sensors are placed at the pump outlet, but if the irrigated area has a lot of topography, that position is often the worst location for the sensor.

Question: where can sensors be placed on pipeline of the VFD?

Answer: at the pump outlet,

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In the weighted average dry years, 2020, 2021, 2022, 64% were ranked good, 11% were fair, 3% were wet late, 15% were wet early, 3% were wet all season, and 4% were very wet all season.

Question: what percentage of Nebraska fields were ranked good in the dry years of 2020, 2021, and 2022?

Answer: 64%

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: The analysis focused on dividing the fields into one of six categories based on the soil water levels in the heart of the season (July and August) and on Sept. 15. The six categories were developed based on the readings from the Watermark sensors. The sensors generate data reported in centibars and have a range from 0 (wet) to 240 (dryer) centibars (cb). Centibar is a unit of measure that refers to the force required by the plant to pull the water out of the soil and into the plant. Typically, installations use a set of three sensors, with one sensor installed at six to 12 inches, one at 18-24 inches, and one at 30-36 inches.

Question: How many Watermark sensors are typically installed?

Answer: three

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Getting the crop off to a great start is essential for a successful season. On dry years, it is sometimes necessary to start irrigating in May and June. However, it is critical to monitor soil moisture to balance crop needs with the risk of losing nitrogen and other valuable crop inputs. Monitoring will also help prevent unnecessary irrigation expenses, and if you have a water allocation, avoid using up water that is critical for later growth stages.

Question: what will monitoring soil moisture help prevent?

Answer: unnecessary irrigation expenses,

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Both methods require the basic information for the pivot. All the needed details can be found on the sprinkler chart for the center pivot. The sprinkler chart is the documentation that came with the sprinkler package for the pivot and describes the basic layout of the pivot, water flow rate, pressure, size of each sprinkler, etc. If the current sprinklers on the pivot came with the machine when it was new, the pivot dealer should be able to provide a copy. Otherwise, ask the company that sold the current sprinkler package for it. If you do not have the sprinkler chart, then you will need to determine the needed data by measuring the pivot.

Question: where can all the necessary information be found for determining the chemigation irrigation pump setting for a center pivot irrigation system?

Answer: sprinkler chart

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The difference in cost between the two scenarios is $14.61 per acre.  With 130 acres irrigated the total annual savings from using sensors would equal $1,899.30. From this total we would have to subtract the cost of the sensors. A typical range for sensor prices is as low as $175 for systems with NRD cost share up to $1,500 per year for subscription based services. Therefore, the net savings from using sensors for a 130 acre center pivot could range from $400 to $1,700 per year.

Question: what are the net savings estimated as for a center pivot system irrigating 130 acres?

Answer: $400 to $1,700 per year.

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07?

Answer: 0.87

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: However, VRI is not likely to reduce the consumptive use of water (i.e., evapotranspiration). Producers who are considering whether to invest in VRI technology should carefully consider the potential costs and benefits to determine whether VRI is a good fit for their situation.  Types of VRI equipment systems, prescriptions (the map that tells the pivot how to apply the water), and potential uses are described below.

Question: what is VRI not likely to reduce?

Answer: consumptive use of water

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Soybeans R4 crop stage, the stage of growth is known as end of pod elongation, the approximate days to maturity is 37, and the water use to maturity is 9.0 inches. For Soybeans R5 crop stage, the stage of growth is known as beginning of seed enlargement, the approximate days to maturity is 29, and the water use to maturity is 6.5 inches.  For Soybeans R6 crop stage, the stage of growth is known as end of seed elongation, the approximate days to maturity is 18, and the water use to maturity is 3.5 inches.  For Soybeans R6.5 crop stage, the stage of growth is known as leaves begin to yellow, the approximate days to maturity is 10, and the water use to maturity is 1.9 inches.  For Soybeans R7 crop stage, the stage of growth is known as beginning maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate water use to maturity for soybeans in the R4 crop stage, the stage of growth that is known as end of pod elongation?

Answer: 9.0 inches.

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: There is increasing pressure on our water resources. Concerns about natural ecosystems and the sustainability of groundwater withdrawals are heightening. Domestic and international competition for water between different users is increasing. Agricultural demand by a global population growing both in number and in wealth is rising.

Question: what is happening to agricultural demand by the global population?

Answer: growing both in number and in wealth is rising

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: Crop water use will vary across the Panhandle due to variations in temperature and precipitation events. Crop water use will assist growers with irrigation scheduling and efficient water use.

Question: why does crop water use vary across the panhandle region in Nebraska?

Answer: variations in temperature and precipitation events

Stone, G., & Qiao, X. (2024). Estimated Crop Water Use for May 27-June 2, 2024 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2024/estimated-crop-water-use-may-27-june-2


Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12?

Answer: 0.8.

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Knowing approximately, how much plant available water is remaining in the active root zone is critical for calculating the last few irrigations and will be referred to as the "remaining available water." The best method for determining the amount of remaining soil water is to use a soil water monitoring system.

Question: what is the best method to use for determining the amount of remaining soil water?

Answer: use a soil water monitoring system

Melvin, S. (2019). Scheduling the Last Irrigations in a Year with Delayed Crop Maturity | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2019/scheduling-last-irrigations


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2020, 45% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 21% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 21% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone and 25-36 inch zone became wetter from August to Sept. 15 in 2020?

Answer: 21%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: For dry edible beans in the emergence-10% Cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.07 inches and the estimated water use during the week of June 19-25, 2023 is 0.50 inches. For dry edible beans in the 10-50% Cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.07 inches.

Question: what was the estimated water usage for dry edible beans during emergence ~10% cover crop growth stage during the week of June 19-25 in 2023?

Answer: 0.50 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2017, out of 86 reports, 28% were ranked good, 10% were fair, 13% were wet late, 13% were wet early, 22% were wet all season, and 14% were very wet all season.

Question: In 2017 out of 86 reports, what percentage of Nebraska fields were ranked fair?

Answer: 10%

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: Pressure differences along the system can be attributed to elevation change and pipeline friction losses. When the sprinkler design flow rate varies by at least 10% for more than 15% of the system due to pressure differences, the use of pressure regulators is encouraged.

Question: what are pressure changes along the system attributed to?

Answer: elevation change and pipeline friction losses

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: The top foot will go above field capacity (30cb) after every irrigation or heavy rain. However, if the second foot gets above 30 cb, it would indicate that over-irrigation is occurring. The data in the chart indicated that the field was this dry on a given day and not how many days the soil was drier than 70 cb. The 70 cb level is equal to about 70% of plant available water (PAW) and stress should not start until below 50% of PAW during the summer and 40% in late August and September. Soil types such as those with high sand or clay content would require different levels other than 30 and 70 cb.

Question: what is 70cb equivalent to in terms of plant available water?

Answer: 70% of plant available water (PAW)

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: To learn more about the secondary aquifers of Nebraska, download the Conservation and Survey Division publication titled 'An Overview of Secondary Aquifers in Nebraska' available at http://digitalcommons.unl.edu/conservationsurvey/138. Questions regarding western Nebraska aquifers may be directed to xxxxx xxxxxx atxxxxxxxxxxxxx; questions regarding eastern Nebraska aquifers may be directed to xxxx xxxxxx atxxxxxxxxxxxxx.

Question: what is the link to the Conservation and Survey Division publication titled 'An Overview of Secondary Aquifers in Nebraska' ?

Answer: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Question: what unit is data generated from Watermark sensors reported in?

Answer: centibars

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2017, 72% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 75% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 66% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone and 25-36 inch zone became wetter from August to Sept. 15 in 2017?

Answer: 66%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Once you have your ETgage out, we hope that you will once again post your weekly readings to the NAWMN website at https://nawmn.unl.edu. As a reminder, once you are on the main screen, you can login to your site by entering your site name and password and clicking on 'Login'. Once you have logged in, you will be taken to your weekly data from past weeks, including last year. To enter your weekly data, click on the 'Add new ETgage reading' link which will take you to the data entry page where you can enter your growth stage, rainfall, and ETgage change. If you've forgotten your site name or password, please contact xxxxx xxxxxx at xxxxxxxxxxxxxxxx orxxxxxxxxxxxxx.

Question: where should an irrigator post their weekly evapotranspiration readings using their ETgage?

Answer: NAWMN website at https://nawmn.unl.edu

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: The description of a speed control VRI system is that its application rate is varied by changing the speed of the pivot and that the irrigation management zones are pie slice shaped. Considerations for the speed control VRI system are that it is relatively inexpensive - many picot panels are capable without additional investment. It also needs no special hardware on the sprinklers. Example uses of it are if spatial variation lines up well with pie slices, varying application based on topography (e.g. reduced application on low spots) if it lines up pie slices, multiple crops or varieties under one pivot, and on-farm research.

Question: what are some example uses of speed control VRI systems?

Answer: if spatial variation lines up well with pie slices, varying application based on topography (e.g. reduced application on low spots) if it lines up pie slices, multiple crops or varieties under one pivot, and on-farm research

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: The last few irrigations of the season require some of the most important water management decisions of the year. An extra irrigation may mean wasting 1 to 3 inches of water and 2 to 5 gallons of diesel fuel per acre. Furrow irrigators may want to decide sooner due to the typical higher application amounts with flood, while pivot irrigators can delay the decision and take advantage of any rainfall that may occur.

Question: how many gallons of diesel fuel could be wasted per acre as a result from an extra irrigation late in the season?

Answer: 2 to 5 gallons

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Question: In 2017 out of 86 reports, what percentage of Nebraska fields were considered wet all season?

Answer: 22%

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: For potatoes in the early emergence crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.12 inches and the estimated water use during the week of June 19-25, 2023 is 0.85 inches. For potatoes in the vegetative crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.15 inches.

Question: what was the estimated water usage for potatoes during the early emergence crop growth stage during the week of June 19-25 in 2023?

Answer: 0.85 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: 2) Pump - The pump is a piece that is sometimes overlooked.  Before you start irrigating in the spring make sure you start the dripper to get the line shaft bearings lubed.  It needs 1 gallon of drip oil for every 100 feet of depth.  Set the dripper for 1 drip every 5 seconds.  The pump can only take oil so fast and you can't over oil them.  Also make sure the dripper line is attached and the fittings are tight.

Question: what is the speed the dripper should be set to?

Answer: 1 drip every 5 seconds

Yonts, C. D., Lyon, D. J., Harveson, R. M., Hergert, G. W., Hein, G. L., & Santra, D. (2009). Producing Irrigated Winter Wheat. https://extensionpubs.unl.edu/publication/ec731/pdf/view/ec731-2009.pdf


Context: Also, keep in mind the corn roots grow about an inch each day into soil that is at field capacity, providing much of the water the plants need for that day. Generally, irrigation needs to be delayed until the soil begins to dry down. Furthermore, research conducted in the North Platte area has shown that irrigation could be reduced by one to four inches, compared to a fully irrigated crop, during the vegetative period without a significant yield reduction and can stimulate deeper root growth. For more information, go to "Vegetative Growth Stage Irrigation, Is It Needed This Year?"

Question: what does research in the North Platte area show?

Answer: irrigation could be reduced by one to four inches, compared to a fully irrigated crop, during the vegetative period without a significant yield reduction and can stimulate deeper root growth.

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For loam, very fine sandy loam, or silt loam topsoil which is silty clay loam or silty clay subsoil, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft. For loam, very fine sandy loam, or silt loam topsoil which is medium textured subsoil, the available water in 1 foot of soil at 100% of available water is 2.5 in/ft, the available water in top 4 feet at 100% of available water is 10.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 4.0 in/ft.

Question: what is the minimum balance in top 4 feet at 40% of available water for loam, very fine sandy loam, or silt loam topsoil which is medium textured subsoil?

Answer: 4.0 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: How does CornSoyWater work in the background? CornSoyWater uses crop simulation models (Hybrid-Maize for corn and SoySim for soybean) to predict crop growth, development, crop water use, and soil water balance. Based on the location of the field, the program automatically determines the weather station that is closest to the field in the weather station network, and the soil texture for the field.

Question: what do the crop simulation models CornSoyWater uses predict?

Answer: crop growth, development, crop water use, and soil water balance

Yang, H. (2017). CornSoyWater: An Online App to Aid in Irrigation Management | UNL Water. https://water.unl.edu/article/agricultural-irrigation/cornsoywater-online-app-aid-irrigation-managemen


Context: Variable rate irrigation or VRI is 'the ability to spatially vary water application depths across a field to address specific soil, crop, and/or other conditions' (Evans and others, 2013). This technology has many potential uses that might enhance farm profitability, irrigation water productivity (i.e., yield produced per unit of irrigation water applied), and water quality.

Question: what are 3 potential outcomes of VRI technology use on a farm?

Answer: enhance farm profitability, irrigation water productivity (i.e., yield produced per unit of irrigation water applied), and water quality

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: Determine the average rainfall per week for the remaining weeks of crop growth and add it into the prediction of how much water may be needed from irrigation. This number should be recalculated each week until the crop is mature. Use Figures 2 and 3 to determine the average rainfall per week in August and in September for central Buffalo County. The chart shows that, on average, central Buffalo County gets 0.60 inch of rain per week in August and 0.55 inch per week in September. The crop is expected to continue growing for three weeks in August and two weeks in September. Remaining available water at maturity is 5.25 inches. The you subtract the average august rain for three weeks which is 1.80 inches. Then you subtract the average September rain for 2 weeks which is 1.10 inches. This gives us that the water we need after accounting for average rain is 2.35 inches. The chart predicts that if average rainfall is received over the next five weeks, only 2.35 inches of irrigation would be needed to mature the crop.

Question: how long is the crop expected to continue growing in September in central Buffalo County?

Answer: two weeks

Barker, J. B. (2017). Considerations in Adopting Variable Rate Irrigation for Center Pivots and Lateral Systems. http://extensionpublications.unl.edu/assets/pdf/ec2000.pdf.


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In the weighted average dry years, 2020, 2021, 2022, 64% were ranked good, 11% were fair, 3% were wet late, 15% were wet early, 3% were wet all season, and 4% were very wet all season.

Question: what percentage of Nebraska fields were very wet all season in the dry years of 2020, 2021, and 2022?

Answer: 4%

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: Strategies for Early Season Irrigation Last year's irrigation will have left the soil fairly wet compared to dryland fields. On a typical year, a silt loam soil that was reasonably well irrigated the previously year (full yield) may only hold two to four inches of water from precipitation in the non-growing season. Sandy soils will hold even less. This means most years, irrigated fields will be at or above field capacity in May, particularly in the eastern two-thirds of Nebraska.

Question: how much water from precipitation in the non-growing season will a silt loam soil that was irrigated well the year prior hold?

Answer: two to four inches of water

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Center pivot irrigation systems are designed and managed to apply water as uniformly as possible to enhance crop production. Uniformity has a direct effect on the system's overall application efficiency, which is a measure of how well an irrigation system delivers water to a crop's root zone.

Question: what is application efficiency a measure of?

Answer: how well an irrigation system delivers water to a crop's root zone

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18?

Answer: 0.72

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Different methods can be used to determine how many gallons/hour (gph) the chemigation injection pump should be set to inject. We are going to talk about two of them today. The first one is using the 'speed chart' (water application depth per pass chart) in the 'sprinkler chart' for the pivot or looking up circle time on the computer panel or the pivot app. The second one involves calculating the chemical injection rate using a spreadsheet. This method gives you more details about the system and is still easy to figure. You will just need to enter the basic information for the pivot. If you are interested, download the spreadsheet from UNL Water.

Question: what is one method that can be used in determining how many gallons/hr (gph) the chemigation injection pump should be set to?

Answer: 'speed chart' (water application depth per pass chart) in the 'sprinkler chart' for the pivot or looking up circle time on the computer panel or the pivot app

Answer: calculating the chemical injection rate using a spreadsheet

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Other secondary aquifers in eastern Nebraska include the Niobrara aquifer (230 wells, mostly in Cedar County), the Codell aquifer (70 wells in Knox and Boyd counties), and the Western Interior Plains Aquifer System. Only one active well is currently installed in the Western Interior Plains Aquifer System in Nebraska, but the aquifer system was a historic source of water to the Omaha area, and still supplies huge volumes of water to Iowa and other states to our east.

Question: how many wells are in the Niobrara aquifer?

Answer: 230

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Center pivot manufacturers have developed options to place the pressure sensor somewhere on the center pivot. Part of Brar's thesis research evaluated where the pressure sensor should be located to achieve maximum energy conservation.

Question: who has developed options to place the pressure sensor somewhere on the center pivot?

Answer: Center pivot manufacturers

Kranz, B. (2018). Economics of Variable Frequency Drives for Irrigation Pumps. UNL CropWatch. https://cropwatch.unl.edu/2018/economics-variable-frequency-drives-irrigation-pumps


Question: what is the minimum balance in top 4 feet at 40% of available water for loam, very fine sandy loam, or silt loam topsoil which is silty clay loam or silty clay subsoil?

Answer: 3.2 in/ft

Answer: 2.5 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: However, the data shows that in the dry years, 2020, '21 and '22, 15-20% of the irrigators let their fields get dry late in the season, maybe even dry enough to have resulted in small yield losses. So, in dry years, data driven decisions could lead some irrigators to apply more water.

Question: in the dry years of 2020, 2021, and 2022 what percentage of irrigators let their fields get dry late in the season?

Answer: 15-20%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: For alfalfa in the stage 4 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 1.22 inches and the estimated water use during the week of June 19-25, 2023 is 2.05 inches. For alfalfa in the maturity crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 1.30 inches. For alfalfa in the full cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 1.18 inches.

Question: what is the estimated water usage for alfalfa during the stage four crop growth stage during the week of June 12-18 in 2023?

Answer: 1.22 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: 1) Pumping Plants - Electric motors account for the majority of the pumping plants in Nebraska, about 55% according to 2013 NASS Irrigation Survey.  They are relatively maintenance free but still need to be looked over.  It is a good idea to change the oil in the unit every year.  Next, open up the junction box and make sure the connectors are tight and have a good ground.  Also check for frayed wires and damage from rodents.

Question: what should be changed in an electric motor every year?

Answer: the oil

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: Beans develop based on day length. So with the same hot dry windy conditions, they will use more water per day and will still mature at about the same date resulting in more water use than predicted in the charts. Thus, it is very important to monitor soil water in beans until they reach maturity. For additional details and charts, see NebGuide Predicting the Last Irrigation of the Season.

Question: what is very important to monitor in beans until they mature?

Answer: soil water

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For silt clay or clay, the available water in 1 foot of soil at 100% of available water is 1.6 in/ft, the available water in top 4 feet at 100% of available water is 6.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.6 in/ft. For fine sandy loam, silty clay loam, or clay loam, the available water in 1 foot of soil at 100% of available water is 1.8 in/ft, the available water in top 4 feet at 100% of available water is 7.2 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.9 in/ft. For sandy clay loam, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft.

Question: what is the amount of available water in units of (in/ft) for fine sandy loam, silty clay loam, or clay loam soils at 100% of available water in 1 ft of soil?

Answer: 1.8 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Risk of Early Season Leaching Excess irrigation has its own risks. Generally, when the soil is above field capacity, excess water leaves the root zone, called deep percolation. This is an essential function of the soil for groundwater recharge. When deep percolation takes agrichemicals past the root zone, it is called leaching. May and June are the most critical time for leaching losses all year.

Question: what is deep percolation?

Answer: when the soil is above field capacity, excess water leaves the root zone

Barker, J. B. (2017). Considerations in Adopting Variable Rate Irrigation for Center Pivots and Lateral Systems. http://extensionpublications.unl.edu/assets/pdf/ec2000.pdf.