Ibukun Timothy Ayankojo and Kelly T. Morgan, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL
Increase in agricultural water consumption through irrigation and the demand for water conservation are reasons for a global effort in the reduction of agricultural water use through increasing water use efficiency (WUE). Increasing WUE will increase water savings and reduce the negative environmental consequences of excessive irrigation. The focus of this study was to evaluate and compare irrigation schedule by a real-time scheduler - SmartIrrigation vegetable (App) with a historic ET irrigation recommendation by UF/IFAS (IFAS). We compared both scheduling methods (App and IFAS) for water savings, productivity and efficiencies in open-field tomato production. Irrigation schedule from both scheduling methods was evaluated at four water application volumes (66% App, 100% App, 150% App, and 100% IFAS) in a randomized complete block design over two production seasons (fall 2015 and spring 2016). Nutrient application was the same for all treatments according to UF/IFAS recommendation. For both seasons, depth of irrigation water applied increased in the order of 66% App < 100% App < 100% IFAS < 150% app. Total water savings was higher for 100% App schedule compare to 100% IFAS at 17% and 15% for fall and spring seasons respectively. Based on productivity, 66% App was highest in WUE at 161 kg m-3 during fall season but WUE was similar with 100% App during spring. Nitrogen use efficiency (NUE-N) was highest for 100% app (0.44 kg.g--N and 0.36 kg.g--N for fall and spring seasons respectively) compare to other irrigation volumes for both seasons. Lower yield and efficiencies observed for both 100% IFAS and 150% App were attributed to nutrient leaching from high water application. Our results suggest that the use of a real-time irrigation scheduler (SmartIrrigation vegetable App) for irrigation scheduling in tomato production can increase water savings, improve NUE by reducing leaching and also maximize tomato yield.