Effect of Controlled-Release Nitrogen Fertilizers on Yield and Nitrogen Absorption by Potatoes, Cantaloupes, and Tomatoes1

Abstract

Abstract In field studies with potatoes, cantaloupes, and tomatoes, using N sources banded in the soil, highest yields were obtained with (NH4)2SO4. Yields with urea-formaldehyde and sulfur-coated urea were similar to each other, and less than those from urea. Nitrogen absorption, as determined by NO3- concn in the petiolar tissue or total N absorption by the entire plant, was in the same sequence as yields. Controlled-release fertilizers did not increase N absorption during late growth. About 90% of the N from (NH4)2SO4 and urea had nitrified and leached from the fertilizer band within 40 days after application. In contrast, about half of the N from urea-formaldehyde remained in the fertilizer band 120 days after application.