Development of a sensor-based algorithm to determine the mid-season nitrogen requirements in deficit irrigated corn production

Abstract. Applying insufficient nitrogen (N) for a highly responsive crop, such as corn, results in lower grain yield, quality, and profits. On the other hand, when nitrogen is applied in excess of crop needs, profit is reduced and negative environmental consequences are likely. The objective of this study was to develop and employ a sensor-based algorithm to determine the mid-season N requirements for deficit-irrigated corn in Coastal Plain soils. The algorithm was developed using varied prescription rate N plot on two soil types. The test plots received nine different rates of N fertilizer (0, 22.5, 45, 90, 135, 180, 225, 270, and 292 kg N/ha). N treatments were replicated 5 times in plots of each soil type using a Randomized Complete Block design. A 6-row GreenSeeker optical sensor was used to measure corn plant‘s NDVI, between the V6 to V8 growth stages. The sensor readings were used to develop the algorithm to be used in the estimation of side-dress N application in corn. There was a good correlation between combined sensor readings collected during the 2015 and 2016 growing seasons (V6 to V8 stage) and actual corn yields (R²>0.68). In Season Estimated Yield (INSEY) was used along with the actual yield to produce a yield potential for each growing season for deficit-irrigated corn crop. The recommended algorithm reduced N application rates by 21% and 34% in soil types 1 and 2, respectively, compared to the normal grower practice (226 kg N/ha) with no reduction in corn yields.