生物炭和秸秆还田对华北农田玉米生育期土壤微生物量的影响

基于华北农田长期定位试验,研究了长期施用生物炭和秸秆还田对整个玉米生育期内土壤微生物量的影响.试验共设4个处理:CK(单施氮磷钾肥)、C1(生物炭4.5 t·hm^-2·a^-1+氮磷钾肥)、C2(生物炭9.0 t·hm^-2·a^-1+氮磷钾肥)和SR(秸秆还田+氮磷钾肥).结果表明,各处理土壤微生物量碳、氮(MBC、MBN)动态变化趋势基本一致,均在玉米拔节期达到最高值,施用生物炭和秸秆还田均显著提高了土壤MBC、MBN含量(P <0.05),并且随着施炭量的增加而增加.与CK相比,C1、C2和SR处理的土壤MBC和MBN分别提高了105.2%、146.5%、96.4%和123.9%、183.6%、114.3%;与秸秆直接还田相比,施用高量生物炭更有利于增加土壤MBC、MBN含量.土壤MBC、MBN均与土壤温度呈现显著的正相关关系,而与土壤水分的相关性较差,说明在玉米生育期土壤温度是影响土壤微生物量变化的主要因素之一.施用生物炭显著降低了MBC、MBN的季节波动,而对土壤微生物量碳氮比(MBC/MBN)没有显著影响.综上所述,施用生物炭更有利于维持较高的微生物活性和较稳定的土壤环境.

Effects of Biochar and Straw Direct Return on Soil Microbial Biomass During Maize Growth Season in North China Plain

Biochar and straw direct return to field can increase soil organic carbon and may thus improve soil microbial biomass. In a long-term experiment in the North China Plain, we studied the effects of biochar and straw direct return to field on soil microbial biomass during maize growth period. This experiment consisted of four treatments(CK, C1, C2, SR) with three replication:CK(NPK fertilizer alone), C1(biochar 4.5 t·hm^-2·a^-1+NPK fertilizer), C2(biochar 9.0 t·hm^-2·a^-1+NPK fertilizer) and SR(straw return+NPK fertilizer). Results showed that soil microbial biomass carbon and nitrogen(MBC, MBN) had similar seasonal variations and they reached the highest at maize jointing stage. Biochar addition and straw return significantly increased the content of soil MBC and MBN. Such effects increased with biochar rates. Compared with CK, soil MBC and MBN in C1, C2 and SR treatments were increased by 105.2%, 146.5%, and 96.4% and 123.9%, 183.6%, and 114.3%, respectively. High amount of biochar was more helpful to increase soil MBC and MBN than straw return was. Soil MBC and MBN was positively correlated with soil temperature, but had no correlation with soil moisture. Soil temperature was one of the main factors affecting soil microbial biomass during maize growth period. Furthermore, biochar significantly reduced the seasonal fluctuation of MBC and MBN, but showed no significant effects on soil MBC/MBN ratio. In summary, applying biochar would be helpful to maintain high and stable microbial biomass of soil.