黄土丘陵区纸坊沟流域植被恢复的土壤养分效应

经过 2 0 a多的人工恢复和封禁措施 ,纸坊沟流域内的植物群落对土壤养分产生明显影响 ,植被对土壤养分的作用表现为 ,在植被作用下土壤有机质、全氮、水解氮、全磷、速效磷向土壤上层富集 ,但不同植被对养分的影响不同。从土壤剖面来看 ,植被对 0— 2 0 cm土壤养分作用大于 2 0— 4 0 cm;从植被生活型来看 ,草本对 0— 4 0 cm土壤养分的提高作用大于乔木和灌木。土壤全氮与土壤有机质之间有良好的线性相关关系 ,土壤全磷与土壤有机质之间也有一定的线性相关关系 ,其中 0— 2 0 cm相关性好 ,但 2 0— 4 0 cm相关性较差 ,说明土壤有机质的累积和分解对土壤全磷和全氮有重要影响

Effect of Vegetation Restoration on Soil Nutrient Changes in Zhifanggou Watershed of Loess Hilly Region

To research the crop potential productivity can find the obstacle to improve yield, and can offer grounds for programming agricultural production. The temperature and climate potential productivity of Changwu experimental district in many years are compared with practical yield of winter wheat and spring maize. The results show that the wheat average heat potential productivity of the district in many years is 6910.5 kg/hm², that of maize 10718.6 kg/hm², the variance between years is not big. The wheat average climate potential productivity is 6190.3 kg/hm², that of maize is 8768.7 kg/hm²; variance between years very large in 1986-1990, the realizing rate is comparative low, but in 1990-1994, the rate is very high, almost equal to the climate potential productivity of the district. The items that are important in the future are: to stable chemical fertilizer application and rational proportion between N and P; to universe use of film mulches and stubble mulches; to increase the mount of organic fertilizer and the efficiency of field managements.