Comparison of soil N availability and leaching potential, crop yields and weeds in organic, low-input and conventional farming systems in northern California

摘要: Increasing dependence on off-farm inputs including, fertilizers, pesticides and energy for food fiber production in the United States elsewhere is of questionable sustainability resulting environmental degradation human health risks. The organic (no synthetic fertilizer or pesticide use), low-input (reduced amount farming systems are considered to be an alternative conventional systems, enhance agricultural quality. Soil N availability leaching potential, crop yields weeds important factors related quality, yet information long-term system effects these factors, especially limited. Four systems: organic, low-input, (synthetic applied at recommended rates) 4-year rotation (conv-4) a 2-year (conv-2) were evaluated soil mineral N, potentially mineralizable (PMN), weed biomass irrigated processing tomatoes (Lycopersicon esculentumL.) corn (Zea mays L.) from 1994 1998 California’s Sacramento Valley. levels during cropping season varied by crop, system, source fertilization. showed 112 36% greater PMN pools than respectively. However, mineralization rates 100% 28% system. Average tomato fruit yield 5-year period (1994–1998) was 71.0 Mg ha −1 average grain 11.6 both not significantly different among systems. had aboveground harvest compared other lower potential risk appear improve quality while maintaining similar yields. © 2002 Elsevier Science B.V. All rights reserved.