长期施肥人工草地土壤养分的剖面变化

The Variation of Soil Nutrients of Long-term Fertilization Artificial Grassland in Soil Profiles

苜蓿连作长期施 P或施 NPM均能增加土壤耕层的有机碳、全氮和碱解氮含量。长期施 NPM对提高整个土壤剖面内的有机碳含量也有显著作用 ,而长期施 P仅能改善土壤耕层有机碳含量 ,对耕层以下土壤的有机碳含量则有降低作用 ;粮草轮作系统中 ,随苜蓿生长年限的增加 ,整个土壤剖面的有机碳含量均有一定程度的提高 ,二、四年生苜蓿土壤的有机碳含量明显高于一年生苜蓿土壤 ,土壤有机碳和全氮的在土壤剖面呈典型的“S”型分布 ,土壤剖面全氮和碱解氮含量变化与有机碳变化有很好的相关性。

Long term growing alfalfa and applying N, P fertilizers can increase contents of organic carbon, total nitrogen and alkali hydrolyzable nitrogen in topsoil. Long term applying NPM evidently increases the content of organic carbon in soil profiles, but long term applying P only improves the content of topsoil organic carbon, by contraries decreases the content under topsoil. The content of organic carbon in total profiles is increased to some extent with the increase of alfalfa plantation years in food grass rotation system. The content of organic carbon in two year and four year alfalfas is evidently higher than one year. The distributions of total nitrogen and alkali hydrolyzable nitrogen take on 'S' shape in soil profiles. At the same time soil organic carbon has well correlation with total nitrogen and alkali hydrolyzable nitrogen.