不同秸秆还田模式的土壤质量综合评价

Comprehensive evaluation of soil quality under different straw returning modes

【目的】对不同秸秆还田模式下的土壤质量进行综合评价,筛选相对较优的秸秆还田模式,为关中平原小麦-玉米一年二熟轮作体系下大规模实行机械化秸秆还田提供理论依据。【方法】采用田间定位试验,在陕西关中冬小麦-夏玉米一年二熟耕作制度下,小麦秸秆设高留茬还田(WH)、粉碎还田(WC)和不还田(WN)3种还田方式,玉米秸秆设深松还田(MM)、旋耕还田(MC)和不还田(MN)3种还田方式,通过完全随机区组设计得到9种秸秆还田模式,分别为WH-MM、WH-MC、WH-MN、WC-MM、WC-MC、WC-MN、WN-MM、WN-MC、WN-MN,测定不同秸秆还田模式下的土壤理化性质,根据主成分分析法定量评价不同秸秆还田模式对土壤质量的影响。【结果】秸秆还田对土壤速效养分和有机碳活性组分的影响较大,尤其是速效氮,其变异系数最高,达32.38%,是反映土壤质量变化最为敏感的指标。秸秆还田后其自身所含有机碳矿化以CO_2形式释放于大气,进入土壤较少,因此土壤总有机碳含量的变异系数较小,为5.31%。通过主成分分析法建立了土壤质量综合评价模型,经计算可知,小麦秸秆高留茬还田-玉米秸秆旋耕还田(WH-MC)模式的土壤质量综合得分最高,达0.751 0,其小麦籽粒和秸秆产量较高,土壤质量相对较优。【结论】综合土壤质量和作物产量,WH-MC是关中地区相对较优的秸秆还田模式组合。

【Objective】This study comprehensively evaluated soil quality under different straw returning modes to screen better straw returning mode and provide theoretical basis for large-scale implementation of mechanized straw returning in Guanzhong Plain under wheat/maize rotation system.【Method】A field experiment was arranged under wheat/maize rotation system in Guanzhong Plain,Shaanxi.Straw mulching with high stubble returning to field（WH）,straw chopping returning to field（WC）and no straw returning（WN）were tested during wheat season,and straw chopping returning to field with subsoiling（MM）,straw chopping returning to field（MC）and no straw returning（MN）were tested during maize season with a total of 9combined straw returning modes：WH-MM,WH-MC,WH-MN,WC-MM,WC-MC,WC-MN,WN-MM,WN-MC,and WN-MN.Soil physical and chemical properties under different straw returning modes were determined and principal component analysis（PCA）was adopted to quantitatively e-valuate the effect on soil quality.【Result】Straw returning to field mainly influenced soil available nutrients and active component of soil organic carbon.Soil available nitrogen had the highest variation coefficient of32.38% and was the most sensitive indicator reflecting the changes of soil quality.Organic carbon was released to atmosphere in the form of CO2 by mineralization after straw returned to field,resulting in small variation coefficient of 5.31%.According to the established comprehensive evaluation model soil quality,wheat straw high stubble returning-maize straw rotary returning（WH-MC）had the highest soil quality comprehensive score（0.751 0）and better soil quality.【Conclusion】Considering soil quality and crop yield,WH-MC is the suggested straw returning mode in Guanzhong Plain.