大豆重茬对黑土团聚体及腐殖质结合形态的影响

Effects of Soybean Continuous Cropping on the Aggregation and Combined Forms of Humus in Black Soil

选取正茬、重茬1年和重茬3年后的黑土,对其团聚体及腐殖质结合形态进行测定,探明大豆重茬对黑土团聚体及腐殖质结合形态的影响。结果表明,与正茬相比,重茬3年后土壤>5mm机械稳定性团聚体数量降低33.4%;重茬3年的重组有机质和复合有机质、有机碳、pH值分别降低8.3%,9.1%,10.5%,0.19;重茬3年后土壤解氮含量增加26.0%;速效钾降低16.4%。与正茬相比,重茬3年土壤的松结态腐殖质、稳结态腐殖质含量分别增加35.3%,64.3%;重茬3年的联结态腐殖质、紧结态腐殖质分别降低16.7%,37.5%;重茬3年的松结态胡敏酸增加62.5%,联结态胡敏酸减少15.8%。正茬土壤松结态胡敏酸的E4/E6显著高于重茬3年;而重茬3年稳结态胡敏酸的E4/E6显著高于正茬。综上,大豆重茬对黑土中>5mm的团聚体数量及腐殖质结合形态产生了影响。

Selecting the rotation, continuous 1 and continuous 3 in black soil, the effect of soybean continuous cropping on the aggregation and combined forms of humus was studied in this experiment. The results showed that it decreased by 33.4% that 〉5 mm size fraction particles of aggregates of soil mechanical stabili- ty in continuous 3 compared with rotation. It gradually decreased by 8.3%, 9.1%, 10.5%, 0.19 that heavy group, complex organic matter, organic carbon, pH, respectively. The content of alkaline hydrolysis nitro- gen content increased by 26.0% in continuous 3 compared with rotation. The content of available potassium decreased by 16.4% in continuous 3 compared with rotation. The content of loosely and stably combined-HA increased by 35. 3%, 64. 3% in continuous 3 compared with rotation. While the content of unitedly and tightly combined-HA decreased by 16.7% ,37.5% in continuous 3 compared with rotation. The content of humic acid in loosely combined increased by 62.5 % in continuous 3 compared with rotation. The content of unitedly acid in loosely combined decreased by 15.8%o in continuous 3 compared with rotation. With respect to continuous 3, the loosely combined-HA of rotation resulted in significant adding of E4/E6. While the E4/ E6 of stably combined-HA from continuous 3 showed higher than that from rotation. In summary, soybean continuous cropping affected on the 〉5 mm aggregation and combined forms of humus in black soil.