Prescriptive–corrective nitrogen and irrigation management of fertigated and drip-irrigated vegetable crops using modeling and monitoring approaches

The combined use of fertigation and drip irrigation to frequently apply small amounts of N throughout a crop provides the technical capacity for precise N and irrigation management. A prescriptive–corrective management (PCM) package, based on modeling and monitoring approaches, was developed for combined irrigation and N management to take advantage of this technical capacity in a greenhouse-based vegetable production system. For irrigation, the prescriptive component of PCM was the calculation of historical ETc using the simulation model PrHo to calculate ETc with long term climatic data, and the corrective component was the use of tensiometers. For N, the prescriptive component was based on simulation of crop N uptake, using the simulation model Nup, developed in the present study, and the corrective component was based on controlling soil solution [NO3−] in the immediate root zone of the plants. Combined PCM for both N and irrigation management was compared with conventional management (CM) for pepper and muskmelon crops. In both crops, fruit production was very similar in the CM and PCM treatments. Using PCM, total irrigation volume was reduced by 17% in pepper and by 20% in muskmelon; total drainage was reduced by 53 and 49%, respectively. Total applied N was reduced by 35% in pepper and by 29% in muskmelon. Total NO3− leaching loss was reduced by 58% in pepper and by at least 49% in muskmelon. The Nup simulation model of crop N uptake was calibrated and validated for pepper and muskmelon. This study demonstrated the effectiveness of combined PCM of both N and irrigation to take advantage of the advanced technical capacity of combined fertigation and drip irrigation systems for precise N and irrigation management.