Nitrogen and Potassium Application Scheduling for Drip-irrigated Tomatoes

Abstract

Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on a fine sand and on a fine sandy loam to evaluate the effect of N and K time of application on yield. On the sandy soil, 196–112 kg of N–K/ha was applied with 0%, 40%, or 100% preplant with 100% or 60% applied in six or 12 equal or in 12-week variable applications. Marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip-applied, and highest with 40% preplant with 60% drip-applied. With 100% drip-applied, yields were highest with 12 even than with six even weekly applications or with 12 variable N and K applications. With the 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, where only N was applied (196 kg·ha–1), yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip-applied, and lowest with all N drip-applied. In 1994, when excessive rains occurred, yields were similar with all preplant and with split-N applications.