Soil and plant mineral nutrition and fruit quality under organic, conventional, and integrated apple production systems in Washington State, USA

摘要

A 1.6-hectare study site, planted in 1994 at a commercial apple orchard in Washington state, USA, consisted of four replicate plots of each of the following three apple (Malus x domestica Borkh. cv. 'Golden Delicious') production systems: organic, conventional, and integrated. One objective of this study was to assess the long-term effects of these production systems on soil/plant mineral nutrient relations and fruit quality. Organic soil management practices have included additions of composted poultry manure and bark mulches, woven polypropylene fabric, and mechanical tillage for weed control. Conventional soil management practices included synthetic fertilizers and herbicides for weed control. The integrated treatment utilized a combination oforganic and conventional practices. After five years under these production systems, total topsoil N was significantly higher in the organic and integrated systems compared to the conventional system, although nitrate N was lowest in the organic system.Even though these differences in available soil N have not led to differences in leaf N among the three systems, the lower available soil N in the organic system is associated with significantly lower fruit tissue N. Fruit Ca contents have consistently risen in all three production systems over the four cropping years. In addition, there were significant differences in fruit nutrient ratios among the three systems. These differences are discussed in terms of fruit quality under the varying soil management practices inherent among organic, conventional, and integrated apple production systems.