Improving soil fertility of apple orchard with organic fertilizer application in Loess Plateau area of Northwest China

The combined application of organic and chemical fertilizers is considered to be a more scientific and reasonable fertilization method compared with the single application of chemical fertilizer in apple orchard, Loess Plateau arid region. The reasonable fertilization can compensate the competition of cover crop for soil nutrients to a certain extent. The field experiment was established in the apple orchard with a split-plot design in 2008, with two main orchard plots under cover cropping and no cover cropping, where four subplots received no fertilizer, single chemical fertilizer, single organic fertilizer and combined application of organic and chemical fertilizer. The content of soil organic matter was determined in this study. We found that cover cropping with organic and chemical fertilizers had a more significant effect on soil organic matter content than other treatments, and cover cropping could effectively increase soil organic matter content compared with no cover cropping. Therefore, cover cropping and fertilization can improve soil fertility by comprehensively regulating organic matter turnover, which provides a strong theoretical support for the mechanism of soil nutrient improvement in orchards.