Tomatoes respond to simple drip irrigation schedule and moderate nitrogen inputs

Abstract

A 2-year trial on scheduling irrigation for fresh market tomatoes was carried out during 1990-91 at the field station in Irvine. Scheduling was based either on estimates of evapotranspiration generated by the California Irrigation Management and Information System (CIMIS) computerized weather network, modified for crop growth stage by multiplying by predetermined crop coefficients (1) or estimates of the percentage soil surface covered by foliage (2), or (3) based on deficit irrigation (irrigation at 20% depletion of available moisture, determined by tensiometers). A trial was also carried out in the San Joaquin Valley using scheduling method (2) in 1992. Scheduling irrigation according to CIMIS evapotranspiration data and plant canopy development proved simple and efficient in both trials. A drip irrigation/nitrogen fertigation study, carried out in the San Joaquin Valley, confirmed results of previous studies which indicated that N applications in excess of 200 lb/acre are seldom required. A new, portable device, which enables growers to measure petiole nitrogen without leaving the farm, is also described. Record - 236