Tomato fruit yield response to nitrogen source and percentage of drip- or band-applied nitrogen associated with leaf potassium concentration

Field experiments were conducted during the spring and fall of 1994 to evaluate two nitrogen (N) sources [ammonium nitrate (AN) and polymer-coated urea (PCU)] and five levels of drip-or band-applied N on the yield of drip irrigated 'Solar Set' tomatoes (Lycopersicon esculentum Mill). Early-season yields obtained with PCU were similar to or greater than yields obtained with AN. Highest yields of large fruit early in the season were produced with 100% preplant-applied AN or 100% band-applied PCU. Total-season yields were greater with AN than PCU and were not affected by placement of N. Increasing the percentage of drip-or band-applied N resulted in leaf N concentrations that were inconsistent with trends in marketable fruit production; however, trends in leaf K concentration early in the season were similar to those of early-season large fruit yields.