Linkages between straw decomposition rate and the change in microbial fractions and extracellular enzyme activities in soils under different long-term fertilization treatments

In order to study the linkages between straw decomposition rate and the change in soil biological properties after straw addition to different fertilized soils, we collected soils from three long-term fertilization treatments (no-fertilizer, CK; nitrogen, phosphorus, and potassium fertilizers, NPK; NPK plus straw (S), NPKS), and incubated maize straw with these soils at 25°C for 75 days. The average straw carbon dioxide (CO2) emission rate in the CK+straw (S), NPK+S, and NPKS+S treatments was 0.58±0.51, 0.66±0.53, and 0.74±0.58 μg C g−1soil h−1, respectively. The average increase in the contents of fungi, bacteria, and Actinomycetes under straw addition treatments than the control soils (CK, NPK, and NPKS, respectively) changed in the order of CK+S≤NPK+S 2 emission rate was poorly correlated with changes in the contents of microbial fractions across all straw addition treatments, but it was significant positively correlated with the increased activities of BG, CB, and XYL under the NPK+S and NPKS+S treatments. Our results indicated that chemical fertilization and straw return soils differently increased straw decomposition because of the different increases in microbial fractions and soil enzyme activities when compared to the no-fertilizer soil, and the decomposition process was more closely correlated with C-obtaining enzymes than microbial fractions.

为探究秸秆还田至不同施肥土壤后，秸秆分解速率与土壤生物学特性变化之间的关联，本研究采集了3种长期施肥处理的土壤：不施肥处理（CK）、氮磷钾肥料配施处理（NPK）、氮磷钾配施秸秆还田处理（NPKS），并将玉米秸秆与上述土壤在25℃下恒温培养75天。CK+秸秆（S）、NPK+秸秆（S）与NPKS+秸秆（S）处理的秸秆二氧化碳（CO₂）平均排放速率分别为0.58±0.51、0.66±0.53和0.74±0.58 μg C g⁻¹土壤·h⁻¹。相较于各自对应的对照土壤（CK、NPK与NPKS），秸秆还田处理下真菌、细菌与放线菌含量的平均增幅依次为CK+S≤NPK+S<NPKS+S。在所有秸秆还田处理中，秸秆CO₂排放速率与微生物组分含量变化的相关性均较弱，但在NPK+S与NPKS+S处理组中，其与BG、CB及XYL活性的提升量呈显著正相关。本研究结果显示，相较于不施肥土壤，化学施肥与秸秆还田土壤可通过改变微生物组分与土壤酶活性的提升幅度，对秸秆分解产生差异化调控作用；且秸秆分解过程与碳获取酶活性的相关性，显著高于其与微生物组分含量变化的相关性。