不同的土壤培肥措施对低肥力农田土壤微生物生物量碳的影响

Impact of soil fertility maintaining practice on soil microbial biomass carbon in low production agro-ecosystem in northern China

为了研究华北农田生态系统化肥、秸秆还田和有机肥等培肥措施对土壤微生物生物量碳的影响,在山东省桓台县冬小麦套种夏玉米种植模式下的低肥力生产系统中设置了田间试验。田间试验设7个处理,依序为:①全还+化肥(小麦秸杆+玉米秸杆还田+600kgN/(hm2.a)),②全还+化肥+有机肥(小麦秸杆+玉米秸杆还田+有机肥),③麦还+化肥(小麦秸杆还田+600kgN/(hm2.a)),④麦还+化肥+有机肥(小麦秸杆还田+600kgN/(hm2.a)+有机肥),⑤化肥(600kgN/(hm2.a)),⑥麦还双倍+化肥(加倍小麦秸杆还田+600kgN/(hm2.a)),⑦不施肥(对照)。1998年4月至1998年11月田间取样测定了土壤的微生物生物量碳。试验结果显示:在整个试验阶段提高施肥水平微生物生物量碳都明显增加。单施化肥可以增加土壤的微生物生物量碳,有机物配合施用化肥作用更加明显。不同秸秆还田方式(全还、双倍麦还和麦还)对微生物生物量碳影响的季节变化较大。有机肥对提高土壤微生物生物量碳的作用是很明显的。从微生物生物量碳的全年平均值来看,全还+化肥+有机肥处理>麦还+化肥+有机肥处理>全还+化肥处理>双倍麦还+化肥处理>麦还+化肥处理>化肥处理>对照。因此,低肥力的农田生态系统中最好的培肥措施是化肥配施有机物。

The experiment was carried out on cultivation patterns of winter wheat and summer corn in Huantai County, Shandong Province, China. The purpose of the study was to understand how soil fertility maintaining practices, such as chemical fertilizer application, the use of organic manure and the return of crop straw to the field affected soil microbial biomass carbon （MBC） dynamics in a low production agro-ecosystem of northern China. Seven treatments of fertility maintaining practices in the field were carried out （where the symbol ＂ ＋ ＂ means combination application） ：①wheat straw ＋ corn straw ＋ chemical fertilizer, ②wheat straw ＋ corn straw ＋ chemical fertilizer ＋ organic manure, ③wheat straw ＋ chemical fertilizer, ④wheat straw ＋ chemical fertilizer ＋ organic manure, ⑤chemical fertilizer,⑥double wheat straw ＋ chemical fertilizer,⑦ control randomly designed and applied in the experimental plots. The content of soil MBC was measured in laboratory for different crop growth stages. The experimental results showed that： manure application enhanced the content of MBC throughout the experimental stages a single chemical fertilizer application could elevate the content of MBC, but chemical fertilizer cooperating organic material could more increase the content of MBC; and that different compositions of straw （wheat straw ＋ corn straw, double wheat straw and wheat straw） returned to the field produced distinct variations in different seasons. Organic manure showed an obvious increase in the content of MBC. The content of MBC had the following ascending trend with regard to annual average the content of MBC： Wheat Straw ＋ Corn Straw ＋ Chemical Fertilizer ＋ Organic Fertilizer 〉 Wheat Straw ＋ Chemical Fertilizer ＋ Organic Manure 〉 Wheat Straw ＋ Corn Straw ＋ Chemical Fertilizer 〉 Double Wheat Straw ＋ Chemical Fertilizer 〉 Wheat Straw ＋ Chemical Fertilizer 〉 Chemical Fertilizer 〉 Control. Therefore, manure applications heighten soil microbial activity and improve soil fertility. The best soil fertility maintaining practice was a combination of chemical fertilizer incorporating organic material in low fertility agro-ecosystem.