Reducing Nitrogen Leaching from Agriculture: An Essential Step toward Protecting the Environment in High Rainfall Areas of Taiwan

Abstract

ABSTRACT Reducing nitrogen (N) leaching from croplands is important to protect environmental quality and improve recovery of applied N. To contribute to this broader goal of nutrient management, a simple pot experiment evaluated the potential differences among urea (250 kg N ha−1), urea+compost (125 kg N ha−1 from urea + 125 kg N from 8 Mg ha−1 of compost), compost (250 kg N from 16 Mg ha−1 of compost) and a zero control (Ctrl), in terms of their effects on apparent N recovery (ANR), mineral N (Nmin) leaching and soil retention of applied N. Cabbage (Brassica oleraceae L.) and corn (Zea mays L.) were grown in rotation where compost application was not repeated in the 2nd year. Nmin leaching was monitored by adding 83 mm and 62 mm of water fortnightly to cabbage and corn crops, respectively for a total of 28 times in a two-year period. Combined (urea+compost) and independent (compost) treatment application retained 1.5 to 2 times higher N, and lowered 2.1 to 4.6 times Nmin leaching, relative to independent (urea) application. We conclude that farmers’ practice of fertilization that has an inherent problem of N leaching for high rainfall areas in Taiwan could be improved by proper compost and urea combinations within agronomically recommended rates of N application.