长期保护性耕作对黄土高原旱地土壤物理质量的影响

Effects of long-term conservation tillage on soil physical quality of rainfed areas of the Loess Plateau

本研究通过设置在陇中黄土高原半干旱区的小麦→豌豆和豌豆→小麦轮作系统的长期定位试验,探讨了不同耕作方式对耕层土壤物理质量的影响。6种耕作方式包括:传统耕作(T)、免耕(NT)、传统耕作秸秆还田(TS)、免耕秸秆覆盖(NTS)、传统耕作地膜覆盖(TP)和免耕地膜覆盖(NTP)。结果表明,不同耕作方式下耕层土壤容重、孔隙度、坚实度和饱和含水量差异显著,团粒结构、有效水分、水分利用率和饱和导水率差异极显著,耕作方式对土壤温度和田间持水量的影响不明显。通过加乘法则和加权综合法2种模型评价了不同耕作方式下土壤物理质量,P→W(豌豆→小麦)轮作序列下表现为NTS>NTP>NT>TS>T(TP)>TP(T),W→P(小麦→豌豆)轮作序列下表现为NTS>NTP>TS>NT>TP>T,说明免耕的基础上进行秸秆覆盖,有助于形成良好的土壤结构,提高土壤入渗,减少土壤侵蚀,促进土壤物理质量提高。

Long-term field experiments on soil physical quality in rainfed farming systems were conducted in Dingxi on the western Loess Plateau.The effects of conventional tillage and five conservation agriculture patterns [conventional tillage（T）,conventional tillage with stubble incorporation（TS）,no till with no stubble（NT）,no till with stubble retention（NTS）,conventional tillage with plastic mulching（TP） and no till with plastic mulching（NTP）] were studied.The experiment was fully-phased with two rotation sequences.Phase 1 started with field pea（Pisum sativum） followed by spring wheat（Triticum aestivum）（P→W） whereas phase 2 started with spring wheat followed by field pea（W→P）.There were highly significant differences between the six tillage measures in soil properties including soil aggregates,available water content,water use efficiency and saturation conductivity.There were also significant differences in some soil properties including soil bulk density,total porosity,capillary porosity,non-capillary porosity,soil strength and saturation capacity.There were no significant differences in soil properties such as soil temperature and field capacity.Using the addition and multiplication method,and weighted integrated method,quantitative assessments of soil physical quality in different tillage systems were carried out.The order of soil physical quality index from high to low was NTS,NTP,NT,TS,T（TP） and TP（T） in P→W rotation,and NTS,NTP,TS,NT,TP and T in W→P rotation.The various tillage measures resulted in very different soil physical quality levels.Improved soil structure arose from tillage reduction or residue retention which improved soil structure,enhanced water infiltration,reduced soil and water loss,and hence improved soil physical quality.