Nitrogen and Irrigation Management to Reduce Return-Flow Pollution in the Columbia Basin.

摘要

Cooperative field studies have evaluated dissolved-N levels and leaching,and corresponding crop yields,for potato production practices in the Columbia Basin area of Washington. High dissolved-N levels (with resultant high potential for return-flow pollution) were found throughout the growing season in well-managed potato fields,with levels decreased by decreasing fertilization rate,use of slow-release N fertilizers or nitrification inhibitors,or sprinkler application of N fertilizers. Careful water management with solid-set sprinkler proved capable of maintaining dissolved-N within the root zone of subsequent crops by season's end,even on very sandy sites. Alternate-furrow irrigation proved effective in 'trapping'banded fertilizer N within the plant root zone on heavier-textured furrow-irrigated soils.