生草对黄土高原旱地苹果园土壤性状的影响

对黄土高原渭北苹果园生草土壤性状测定结果表明,生草能降低0~60 cm土层土壤容重,增加土壤孔隙度,提高田间贮水量,且与生草年限呈正相关;能显著提高0~20 cm土层有机质含量,种植禾本科牧草有机质年积累量为0.10%,种植豆科牧草年积累0.15%;随生草年限的增加,较深土层土壤有机质趋于增加,种植白三叶改善较深土层土壤有机质的效果强于种植黑麦草。对N、P、K营养的影响主要表现在0~40 cm土层,生草的前期(4年)土壤养分消耗大于积累,苹果与牧草在该土层存在养分竞争,在第5年全氮、全磷、全钾呈现恢复性增长,全氮、全磷、全钾的演变呈现“S”型的演变过程,但生草能提高0~40 cm土层水解氮、速效磷及速效钾含量,具有活化有机态N、P、K的功能,有利于果树对N、P、K营养元素的吸收利用;生草类型不同,活化N、P效果不同,黑麦草活化P的作用大于白三叶,而白三叶活化N的作用大于黑麦草;生草后土壤三大微生物类群数量及过氧化氢酶、尿酶、碱性磷酸酶活性都显著提高,并随生草年限的增加趋于增加。

Effects of interplanted herbage on soil properties of non-irrigated apple orchards in the Loess Plateau

Herbage interplanted in apple orchards in the Weibei areas of the Loess Plateau reduced soil bulk density while the porosity and the soil water holding capacity were increased in 0-60 cm soil layer.There was a positive correlation with of these factors with the number of herbage growing years.The content of soil organic matter in 0-20 cm soil layer was increased by 0.10% annually in grass family herbage land and by 0.15% in pulse family herbage land.With increased herbage growing years,the soil organic matter increased in 20-60 cm soil layers.The soil organic matter of the deeper soil layer under Trifolium repens was more than that of Lolium perenne land.Effects of interplanted herbage on total N,P,and K were found in the 40 cm soil layer.There was nutrient competition between herbage and apple trees in 0-40 cm soil layers in the four years after planting herbage but in the fifth year,the content of total N,P and K increased.The content of total N,P and K appeared as an "S "type change within five years but the content of hydrolytic N,available P and available K with in 0-40 cm soil layer increased with benefits to nutrient absorption by the apple trees.The activated organic P and hydrolytic N were different with each kind of herbage.The activated organic P in L.perenne land was more effective than that in T.repens land but the hydrolytic N in T.repens land was increased compared with L.perenne land.Planting herbage could increase the amount of three types of microbial groups in soil and the activity of catalase,urease,and alkaline phosphatase with increasing herbage years.