Soil and Plant Nitrogen Dynamics Under Organic Or Conventional Sweet Corn Production Systems.

Improved understanding of nitrogen (N) cycling in agro-ecosystems is essential for increasing N use efficiency and enhancing the sustainability of food production. Many factors influence N cycling and availability to plants in cropping systems, including how the soil is managed. In this study we examined the impacts of managing the soil under organic or conventional N management systems on corn yield, plant uptake of N and soil inorganic N pools. As the demand for organic produce increases, the impact of organic farming on crop productivity and on the ability of the soil to supply nutrients and maintain its functionality needs to be studied. Sweet corn was grown in plots receiving four treatments: Control (no N), ammonium sulfate at 112 (AS100) or 224 (AS200) kg N per ha and poultry litter (PL) at 112 kg per ha. Cornstalk N (%) was highest in the conventional plots, which received N in the form of AS. The greatest difference (p<0.0001) was observed between the AS200 and the Control group with means of 1.75% and 0.79%, respectively.  Post-season NO₃-N pools in the soil were highest for the AS200 and AS100 treatments with means of 30 and 12 kg N per ha, respectively, with no differences between the Organic (N from PL) and Control. No differences were observed in terms of crop yield and plant height.  This, along with the fact that significantly larger N pools remained in the soil post-harvest in the ammonium-sulfate-treated plots, indicates that there is room for improvement in terms of N use efficiency in the conventionally managed plots.