The development of Nitrogen response curves for the improvement of Nitrogen use efficiency (NUE) on Maryland’s Eastern Shore

Abstract. Management of the Soil Nitrogen Cycle is of critical importance to the health of entire ecosystems. Excessive application of Nitrogen (N) fertilizers and the subsequent nutrient enrichment of waterways can be blamed for eutrophication in marine, estuarine and riverine systems. Presently, worldwide nitrogen-use-efficiency (NUE) is said to be less than 50 percent. The remainder of this N is left to enrich the atmosphere as well as ground and surface water, with potentially serious negative impacts. Proper and efficient management of N application both minimizes pollution of groundwater and optimizes profits for producers. Proper assessment of within–field crop variability is critical for improvement of NUE. With appropriate design of sensor and sprayer combination on tractor booms the sensing, calculation of sensor based nitrogen application rates, and nitrogen fertilizer spraying can be implemented on-the-go with microprocessor based sensing and actuation. Critical to this process is the creation of N-application algorithms. To develop such algorithms, field studies are undertaken to determine optimum N application rates. The first two years of this project (2012, 2013) centered on corn (zea mays L.) raised under two water conditions (irrigated and non-irrigated). The experimental layout is a split plot design with irrigation as the main plot and N application levels as the sub-plot. Five (2012) or six (2013) fixed N fertilizer levels were used. Each plot was hand harvested and weighed to calculate an equivalent yield in bushels per acre. In 2013 field experiments an additional factor in the form of drought-tolerant seed (Pioneer Aquamax) was also introduced. Significant effects Nitrogen and Irrigation were observed in 2012. Significant effects of Nitrogen and Seed were observed in 2013.