不同种植模式对土壤氮素转化及酶活性的影响

Effects of different planting modes on soil nitrogen transformation and related enzyme activities.

采用两年大田试验,研究了小麦-大豆(A1)、小麦-甘薯(A2)、玉米(A3)、小麦/玉米/大豆(A4)和小麦/玉米/甘薯(A5)5种种植模式下,小麦/玉米/大豆套作体系的土壤酶活性变化特征及其对土壤氮素转化的影响.结果表明:与A1、A2、A3和A5相比,A4提高了各作物在开花期(或吐丝期)和成熟期的土壤总氮含量及脲酶和蛋白酶活性,处理间表现为套作>单作、大豆茬口>甘薯茬口、边行>中行;降低了小麦、玉米土壤的NO3--N、NH4+-N含量及小麦土壤的硝酸还原酶活性.玉米土壤的硝酸还原酶活性在玉米、大豆共生前的拔节期为单作>套作,在玉米、大豆共生后的吐丝期和成熟期为套作>单作、大豆茬口>甘薯茬口;大豆土壤的NO3--N、NH4+-N含量及硝酸还原酶活性在分枝期为单作>套作,在开花期和成熟期为套作>单作、大豆茬口>甘薯茬口、中行>边行.

A 2-year field experiment was conducted to study the dynamics of soil nitrogen content and urease,proteinase,and nitrate reductase activities in a wheat/maize/soybean relay strip intercropping system under effects of five planting modes,i.e.,wheat-soybean（A1）,wheat-sweet potato（A2）,maize（A3）,wheat/maize/soybean（A4）,and wheat/maize/sweet potato（A5）.Among the five planting modes,A4 increased the soil total nitrogen content and urease and protease activities at flowering（or spinning） and maturing stages,and the total nitrogen content and urease and protease activities were relay strip intercropping single cropping,soybean sweet potato,and fringe row central row.A4 decreased the NO3--N and NH4＋-N contents of wheat and maize soil,and the nitrate reductase activity of wheat soil.The nitrate reductase activity of maize soil was higher in single cropping than in relay strip intercropping at jointing stage but was in adverse at maize spinning and maturiting stages,and the nitrate reductase activity of soybean soil was higher than that of sweet potato soil.At the branching stage of soybean,the soil NO3--N and NH4＋-N contents and nitrate reductase activity were higher in single cropping than in relay strip intercropping;whereas at flowering and maturing stages,the soil NO3--N and NH4＋-N contents and nitrate reductase activity were in the sequences of strip intercropping single cropping,soybean sweet potato,and center row fringe row.