Cauliflower Yield, Biomass Accumulation as Affected by Nitrogen Rates and Irrigation Scheduling

Irrigation and N-fertilizer management are important factors for cauliflower production. Cauliflower is a heavy water user and requires constant supply of water. Suitable management of irrigation and N-fertilizer are required to maximize plant growth, yield, N-fertilizer use efficiency. The objective of this study was to evaluate the N-fertilizer rates and irrigation scheduling on yield and biomass accumulation of cauliflower ‘Snow Crown’ cultivated on plastic mulch with drip irrigation. The experiment was conducted in Hastings, FL, on a sandy, siliceous, hyperthermic Arenic Ochraquaif belonging to the Ellzey series with high water table, about 60 cm below the soil surface. A factorial design included irrigation and N-rate treatments. Irrigation treatments were: SMS, water application controlled by soil moisture sensor (SMS) with base irrigation set at 14% soil volumetric water content (VWC) which was allotted three irrigation windows daily and bypassed events if the soil VWC exceeded the established threshold and TIME, fixed time irrigation being applied three times a day. All treatments received 56 kg·ha^-1 of N pre-plant and additional N-fertilizer via fertigation at rates of 0; 112; 224 and 336 kg·ha^-1. The SMS reduced the number of irrigation events by 82% compared to TIME treatment. There was an interaction between irrigation and N-rate for total plant biomass at 14, 29, 43, 57, and 71 DAT. For SMS, the fertigation rates of 112 and 224 kg/ha N increased plant biomass compared to control (0 kg·ha^-1), at 14, 43, and 57 DAT. The application of 224 kg·ha^-1 of N for SMS resulted in higher plant biomass compared to control, at 71 DAT. Cauliflower yield was on average 41.5 and 34.5 Mg·ha^-1  for SMS and TIME, respectively, and the benefit the reduced irrigation water application with SMS treatment increased cauliflower yield and head weight by 17% on average. Use of N application rate above 280 kg·ha^-1 did not increase yield significantly for either irrigation treatment.