Development and field testing of sensor-based algorithm for N fertilizer management of AZ durum wheat 2015 Final Report

This project is focused on the use of commercially available precision agriculture technology and tested for its capacity to perform variable-rate application of Nitrogen fertilizer in irrigated durum wheat in Maricopa, AZ. The technology tested in this study includes active-light canopy reflectance and displacement sensors, as well as GPS-based rate controllers for application equipment. Multiple years of experimental data on sensor output and corresponding plant conditions are needed to develop an algorithm specific to the conditions and yield goals of Central Arizona. Application equipment and experimental testing of N rates by time of application and amount have been tested for since 2011 in Maricopa AZ with consistent results indicating the feasibility of using active sensors in ground application systems to control the timing and delivery of N fertilizer to optimize production of durum. During the 2015 season the tests included 4 combinations of N fertilizer amounts and application timing. Close monitoring of soil and plant (lower stem) Nitrates, as well as plant biomass was carried out during the early phases of crop development, followed by yield evaluations at maturity. Under the conditions tested during the 2015 season, only small differences in yield were observed as result of amount/timing application treatments. There was a trend of increasing yield by shifting higher amounts towards the flowering stages but these differences were not statistically significant. Protein content was slightly higher for treatments with larger amounts around tillering but these differences were not significant. The experiment in 2015 aimed at evaluating the potential gains of sensor-based management in soils with only moderate-low deficiency levels of N, a condition common in Arizona fields. The results showed that residual Nitrogen in the soil had a buffering effect that reduced the impact of N treatments on crop development and yield.