陕北坡地长期施肥效应及土壤肥力变化

Effeets of Long-term Applying Fertilizer and Changes of Soil Nutrient

坡耕地多年施肥试验表明：肥料效应总趋势为ＭＮＰ＞ＭＮ＞ＮＰ＞Ｍ＞Ｐ＞Ｎ＞ＣＫ，化肥配施效果优于单施，且有机肥与氮磷配施效果最佳，Ｍ，Ｎ，Ｐ交互作用最强，高达６６９ｋｇ／ｈｍ２，作物产量与养分的吸收基本一致。单施化肥土壤有机质变化不明显，而全氮减少，有机肥与化肥配施，其土壤有机质、全氮含量增加。长期施肥土壤碱解氮含量均下降，而有机肥缓解了下降速度。施确处理土壤速效磷增加明显。

The many years experiments in slope farmland show that effects tendency of fertilizer is as follows,MNP>MN>NP>M>P>N>CK,the effects of applying mixed fertilizer is superion to applying single fertilizer,and the effect of applying organic matter mixed with NP is the best,the mutual effects among N,P and M are most powerful,the value of it reached 669 kg/hm2,the crop yield keeps consistent with the nutrient absorbed.Soil organic matter has no obvious change and total N content is decreased as applying single fertilizer,soil organic matter and total N content is increased as applying organic matter mixed with fertilizer.Soil valid N content is decreased as a long-term applying fertilier,but applying organic matter may alleviated this decreasing tendency.Applying P may enhance the soil valid P obviously.