Iowa farmers are being urged to hold off putting nitrogen on their fields for several weeks yet. Elwynn Taylor, an I-S-U extension climatologist, says the chemical can help crops tremendously or damage the environment, depending on when and how it’s applied.Taylor is a spokesman for the state’s nitrogen coalition, comprised of fertilizer dealers, farmers, government agencies, I-S-U and the Agribusiness Association of Iowa. He says temperature is one of the biggest concerns when applying nitrogen.When the soil temp is below 50, nitrogen is very stable and it’ll stay put. If it gets warmer, the nitrogen can convert to other forms which can more easily get into the groundwater and cause pollution problems. Taylor says the soil moisture level is also key as too much moisture can wash out the nitrogen…For more information, surf to “www.extension.iastate.edu” and click on the “N-P-K” link for Nitrogen and Phosphorous Knowledge.