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March 2011 Archive for Ask an Agronomist

RSS By: Farm Journal Agronomists, Farm Journal


How Can I Prevent Wheat From Lodging?

Mar 24, 2011

Question: My biggest issue with raising wheat is to keep it from lodging. I currently have been putting my nitrogen on when the wheat is 6-inches tall, to try to slow down the vegetative growth. Can I put it on later (I don't want to give up any yield potential)? Or, is there a growth regulator or any other product I could use to try and hold down the growth and not suppress yield?

 Answer: Lodging can be a serious yield limiting problem, but without understanding a little more with regards to specific region and some of your field/crop management operations, it’s very difficult to answer your question accurately. However, I suggest that there are a number of management considerations, which can eliminate or at least reduce lodging.
1)     Begin by selecting and planting wheat varieties with high standards of standability. Such varieties are frequently short (but not always) and they almost always have thicker stems, which lead to improved standability plus the ability to push yields higher with elevated nitrogen rates.
2)     Watch your head densities at harvest time. I have frequently seen excessively thick fields of wheat lay flat on the ground with only 100 lb/A of spring-applied nitrogen, alongside the same variety in the next field that had 120 lb/A of spring-applied nitrogen and stood perfectly. The differences were the planting date, seeding rate and timing of the nitrogen applications. Later nitrogen applications, as you explained, should help standability standards, but they may need to be used in combination with the other management practices.
3)     Is your wheat lodging by kinking the stem; or, is the plant falling over within loose saturated soils? There is a big difference, and each of these requires a different management approach.
4)     Watch your diseases, as root and stem diseases can play a big part in standability.
5)     The only affordable growth regulator available currently for wheat within the U.S. is Cerone. Based upon my research and experience, it’s absolutely a last resort after the above management steps have been exhausted. Cerone is very temperature sensitive and can result in significant yield losses if not timed and applied correctly.
Small, incremental management changes can improve your crop.

How Can We Make Cornstalks Break Down?

Mar 21, 2011


How Can We Make Cornstalks Break Down?
Question: We are having a problem getting our cornstalks to break down over winter, and I’m concerned going into spring planting. What can we do to address that?
Answer: We are hearing from farmers on a fairly regular basis about this issue. Striving for higher corn yields, pushing populations to the limit, and demanding healthy corn genetics with good stalk strength, have all caused this extra residue. 
Residue breakdown, for the most part, requires the residue to be in contact with the soil. The soil contains beneficial bacteria and fungi that use the residue as an energy/food source to survive, in the process breaking down the residue. There are several things we need to do to have robust, healthy micro-organism populations. Bacteria and fungi require air, moisture, and good nutrient load, just like the crops we are growing. This requires that we take care of the soil chemistry (pH and nutrients) and soil physical properties (air and moisture movement up and down). 
Uniform Soil Density, a term used frequently at Farm Journal Corn College, allows the proper air and moisture movement for bacteria and fungi. How you handle the residue this spring depends a lot on the soil type. Be careful not to cause more problems, than just heavy residue, by a tillage pass that leaves you in worse shape. Avoid “tough residue times” during early morning, late evening and high-humidity days. Double-check the size of the coulters on your drill/planter, make sure the diameter is at the recommended size and the cutting edge is good. Work on growing beneficial bacteria and fungi, and your crops will thank you.

What Can You Tell Me About APSA 80?

Mar 17, 2011

Question:  I have been asked to try APSA 80 Adjuvant in my corn and alfalfa.  Before I do, I wanted to do some research. The info on the web is conflicting. What can you tell me about this product? (2.5 gal = $100.00: 30 gal drum = $1,049.00)

Answer:  APSA80 is All Purpose Spray Adjuvant formula that includes 80% active ingredients. The adjuvant is a wetting agent that lowers the surface tension of water, which allows spray droplets to spread out on the leaf surface. We have not tested this product. I would treat it like any other adjuvant and price it out according to the recommended use rate.


Do You Recommend Applying Fungicides On Wheat At Green-Up?

Mar 14, 2011

Question: Is there an advantage to applying fungicides on wheat at green-up?  Wheat here has just had nitrogen applied, and growth has really started to jump.  Some consultants are recommending an insecticide and Headline. Some are seeking Prosaro to apply. Wouldn't a fungicide be more beneficial at flag leaf?

Answer: Without knowing the specific region the wheat is planted in and additional information such as the density of the wheat, wheat variety and the specific disease/insect pressure, it’s hard to make any kind of accurate recommendation. However, if the grower or agronomist is scouting the field and finds threshold levels of aphids (5+ in the early spring) or other insects at economic thresholds, then the application of an insecticide would be recommended.
If the wheat is dense and early-season diseases are visible within the canopy, or the variety planted is susceptible to mildew, tan spot, early rust or septoria (these diseases may be specific by the region), then an application of a fungicide early would likely be a good economic decision. Single fungicide applications early in the season have been found to increase yields by 5-7% many times, even at lower rates. These early applications are not a substitute for later season fungicides, however, because fungicides applied at flag-leaf emergence to early heading are timed to protect the flag leaves and grain heads from diseases, preferably all the way through the completion of grain fill.
These steps help wheat growers improve stands and, ultimately, yield results.

How Do I Get The Most From My Potash Application?

Mar 04, 2011

Question: I have been reading several blogs on Agweb on fertilizer recommendations for corn vs soybeans. I was wondering if the potash we put out this year on soybeans was really doing any good or if it was just as well to put out a little more to the corn land the previous year since we have a corn soybean corn rotation. If the beans don't really benefit from applied K then what are my benefits to applying K before I plant soybeans if the soil levels are adequate? Would K be available if I applied it to the bean land in the fall of the previous year after we cut the corn? 

Answer: Soybeans are big users of potash. A 60 Bu/ac soybean crop removes 87 lb K20 which is equal to 145 lbs potash (0-0-60) per acre. A 200 Bu/ac corn crop removes 58 lb K20 which is equal to 97 lbs of potash. So yes, soybeans need potash as well as corn. Depending on soil type and soil test levels some growers choose to apply potash one time for both crops, in this yield example you would need to apply 242 lbs of potash just for crop removal on soybeans and corn. A soil test will tell you what levels you have in the soil. If your soil-test levels are medium or below you may want to consider fertilizing for each crop each year (removal rates + soil test build levels). If you have high soil-test levels you may be able to fertilize two crops in one year. Sandy and sandy loam soils may not be able to hold large amounts of potash, so consider every year spreads on these soil types as well.   Also consider the economic aspects as well. Potash price and grain prices have fluctuated greatly over the last several years. Fall applications of potash can work well.

What Can I Expect From Green Seeker For Variable-Rate Nitrogen?

Mar 01, 2011

Question:  Do you have any experience with systems such as the "Green Seeker" to variable-rate apply nitrogen? If so, what can we expect to accomplish--reduced nitrogen rates or better yields?

 Answer:To date we’ve only been using the sensor to collect vegetative index/crop density data. We are currently studying their application for real time nitrogen variable rate application.
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