Nutrient cycling in the Columbia River Basin eutrophication in part due to the use of the river and its tributaries to irrigate over seven million acres of farmland, an extraction that comprises an average of 93 percent of daily water use in the basin. Natural run-off caused by precipitation and snowpack melt across agricultural lands further transports more of these nutrients into the river. In the late 1990s, the nitrogen load in the Columbia river was over twice the concentration historically observed. Forests are important terrestrial sinks for nutrients due to the ability of vegetation to sequester excess nutrients into their biomass. Additionally, plant roots stabilize soils
Plant nutrition nutrients a plant may be lacking. Many plants engage in symbiosis with microorganisms. Two important types of these relationship are Though nitrogen is plentiful in the Earth's atmosphere, relatively few plants harbour nitrogen-fixing bacteria, so most plants rely on nitrogen compounds present in the soil to support their growth. These can be supplied by mineralization of soil organic matter or added plant residues, nitrogen fixing bacteria, animal waste, through the breaking of triple bonded N molecules by lightning strikes or through the application of fertilizers. At least 17 elements are known to be essential nutrients for plants. In relatively large