秸秆还田与氮肥运筹对农田棕壤微生物生物量碳氮及酶活性的调控效应

Regulation Effects of Straw Returning and Nitrogen Application Management on Farmland Brown Soil Microbial Biomass and Enzyme Activities

如何有效运筹秸秆还田与氮肥施用,研发高效节氮秸秆还田技术,是目前东北地区农业生产中亟待解决的问题。基于田间定位试验,研究了不同秸秆还田方式(秸秆不还田、秸秆粉碎翻压还田、秸秆堆腐旋耕还田)与施氮水平(180、210、240 kg/hm^(2),以纯氮计)运筹对土壤微生物生物量碳、氮(MBC、MBN)和氮代谢关键酶活性的影响,结果表明:与秸秆不还田相比,秸秆还田处理土壤MBC、MBN含量及MBC/MBN比值和脲酶活性均显著增加,硝酸还原酶活性无规律性变化。随着生育期推进,秸秆还田处理土壤MBC和MBN含量分别呈现单峰和双峰曲线变化,脲酶和硝酸还原酶活性均呈波动式变化,高峰期均出现在春玉米旺盛生长期(拔节期至灌浆期)。随着施氮水平增加,秸秆还田处理土壤MBC、MBN含量均增加,MBC/MBN比值降低,而脲酶和硝酸还原酶活性变化行为因秸秆还田方式而异。在保证氮肥总量不变的前提下,秸秆粉碎翻压还田配以15%氮肥后移能够增加土壤MBC和MBN含量,降低MBC/MBN比值。综上,在东北农业产区,秸秆粉碎翻压还田+210kg/hm^(2)氮肥+15%氮肥后移的秸秆还田模式具有优化氮素管理、提高土壤肥力的潜力。

How to effectively manage straw returning and nitrogen(N)application in order to develop the straw-returning technology with efficient N saving is an urgent problem to be solved in agriculture production of Northeast China.With a field positioning experiment,the effects of different straw returning methods(no returning;crushed-returning and ploughing,S;decomposed-returning and rotary tillage,DS)and N application rates(N 180,210 and 240 kg/hm^(2))on soil microbial biomass carbon/nitrogen(MBC/MBN)and the key enzyme activities of N metabolism were investigated.The results showed that compared with no returning,soil MBC and MBN contents,MBC/MBN ratio and urease activity in all S and DS treatments increased significantly,but nitrate reductase activity changed irregularly.With the extension of maize growth period,soil MBC and MBN contents for S and DN treatments showed single peak curve and double peak curve respectively,and urease and nitrate reductase activities both changed with a fluctuating trend,and both reached peak points at spring maize exuberant growing period(jointing stage to filling stage).With increase of N application rate,both soil MBC and MBN contents for all S and DS treatments increased,MBC/MBN ratio decreased,and the changes of urease and nitrate reductase activities differed from returning methods.Under the condition of the same N application rate,S treatment with a 15%postponing of N fertilizer could increase soil MBC and MBN contents,and decrease MBC/MBN ratio.In conclusion,the technology of crushed returning ploughing with N 210 kg/hm^(2) and a 15%postponing of N fertilizer has the potential to improve N management and enhance soil fertility in the agricultural producing areas of Northeast China.