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Quantifying nitrogen leaching from an organic herbicide (corn gluten meal), 2012

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Project Leader: Jenny Kao-Kniffin, Department of Horticulture, Cornell University

Cooperator: Marty Petrovic, Department of Horticulture, Cornell University

Abstract:

The recent NYS law banning conventional herbicides on school grounds (Child Safe Playing Fields Law) could create emerging problems for stormwater pollution management. We anticipate that corn gluten meal applications will increase as few allowable herbicides are available for weed control on school grounds. Lawns treated with corn gluten meal receive more than four times the level of nitrogen recommended by Cornell Turfgrass. We quantified the concentrations of nitrate leached from corn gluten meal, urea, and control plots over the 2012 growing season. We found that additions of urea and corn gluten meal resulted in high levels of nitrates in drainage water several months after the initial application. In contrast to what we expected, urea plots leached higher levels of nitrates compared to corn gluten meal despite starting with a nitrogen application 1/4th of the level found in corn gluten meal. For weed control, corn gluten meal did not show any difference in the suppression of annual crabgrass compared to the control. However, we found that adding low inputs of nitrogen in the form of urea increased the presence of weeds in comparison to the corn gluten meal and control plots. Although corn gluten meal showed no control of annual crabgrass, it can serve as an effective organic fertilizer that minimizes nitrate losses in drainage waters.