黄土残塬沟壑区林粮间作树种枯落叶对连作麦田土壤极化的防治效应

The Prevention Effect of Leaf Litters of the Tree-Crop Intercropping Trees on the Polarization of Continuous Wheat Field Soils in the Residual and Gully Region of Loess Plateau

连作引起的农田土壤性质极化是导致土壤退化和连作障碍的重要原因之一,防治的途径除了进行施加有机肥外,引入种间关系协调的其他树种形成林粮间作复合系统是重要的生态举措。作者通过野外采集黄土残塬沟壑区典型麦田耕层土壤、麦秸和不同树种当年枯落叶后进行室内混合培养试验的方法,对当地连作麦田土壤性质的极化趋势和引入不同林粮间作树种后的种间土壤关系进行了研究。结果表明,①小麦连作会引起土壤有效锌和有机质含量的持续增加和土壤多种酶活性不断提高的正向极化,但同时会引起土壤向贫养化发展。②引入苹果、核桃等8个树种进行林粮间作后,其枯落叶分解均可以防止连作麦田土壤碱解氮不断减少这一负向极化;除桃树、核桃树种外,引入其他树种可以防止土壤脲酶活性不断降低这一负向极化;除杏树外,引入其他树种可以防止土壤速效P含量不断减少这一负向极化;除桑树外,引入其他树种可以防止土壤有效铁含量连续减少这一负向极化。③从枯落叶对麦田土壤的影响角度考虑,最适合进行林粮间作的树种是桃树、核桃,其次是枣树、桑树,较不适宜进林粮间作的树种是柿树、苹果、花椒、杏树。

Farm soil properties polarization caused by continuous cropping is one of the factors Leading to soil degradation and continuous cropping obstacle.In addition to fertilizing the organic manure,introducing other appropriate species to build an composite tree-crop intercropping system is an important ecological measure.Through the method that collect typical wheat field soil,the wheat straw and leaf litters of different trees in the Residual and Gully Region of Loess Plateau,mixed and cultured them in the lab,the author studied the polarization trend of the continuous wheat soil properties and the effect of leaf litters on the soil.The results shows that：（1）The continuous cropping of wheat can cause positive polarization that the increment of the soil organic matter and the improvement of varieties of enzyme activity,however,it can decrease the soil nutrients.（2） The leaf litters decomposition can prevent the negative polarization of the available nitrogen in the continuous wheat field soils after the introduction of the apple trees,the walnut trees,etc.eight intercropping tree species to intercrop with the wheat field soils.Except for the peach trees and the walnut trees,the leaf litters decomposition of other tree species can prevent the negative polarization of the urease;except for the apricot,the leaf litters decomposition of other tree species can prevent the negative polarization of available phosphorus;except for the mulberry,the leaf litters decomposition of other tree species can prevent the negative polarization of available iron.（3） From the effect of leaf litters on the wheat field soil point of view,the most suitable tree species for tree-crop intercropping is the peach trees,walnut trees,followed by the jujube trees,mulberry,followed by the persimmon trees,apple trees,pepper trees,apricot.