Managing Cropping System Energy Demand Through Matching Fertilizer Usage with Crop Requirements.

Nutrient losses through surface runoff or subsurface tile drainage are partially a result of over-application of nutrients. The Iowa Soybean Association STAARS program is an initiative to capture all the components of energy inputs into a crop. The majority of energy inputs into corn crops is associated with fertilizer nutrients. We have collected cropping system input data from _ farmers in six states (South Dakota, Iowa, Illinois, Indiana, Ohio, and Kentucky). The objective of this presentation will be to assess how well nutrient inputs are meeting crop demands. Crop nitrogen needs are evaluated by the comparing the N applied to the crop against the N remaining at senescence, as measured by the corn stalk nitrate test (CSNT). Phosphorus will be evaluated by comparing the phosphorus applied to fields to the soil tests available for each field. The fields where crop nutrients are over-applied also happen to be the fields with the highest energy usage. To ensure the sustainability of agriculture, crop advisors should ensure that fertilizer nutrients will match crop needs. This will not only improve water quality, but lower the energy demands to grow the crops in these fields.