不同秸秆还田方式对土壤质量改良效应的综合评价

Comprehensive evaluation of soil quality under different straw incorporation approaches

2011—2016年采取田间定位试验方法,对比研究了秸秆不还田对照(CK),长秸秆(50 mm)覆盖还田(LM),长秸秆(50 mm)翻压还田(LP),粉末秸秆(1 mm)翻压还田(SP),长秸秆(50 mm)氨化翻压还田(ALP)和粉末秸秆(1 mm)氨化翻压还田(ASP)6种不同秸秆还田方式对土壤质量和冬小麦产量的影响。选择土壤体积质量(X1)、饱和导水率(X2)、饱和含水量(X3)、>0.25 mm水稳性团聚体含量(X4)、水稳性团聚体平均重量直径(X5)、水稳性团聚体几何平均直径(X6)、水稳性团聚体分形维数(X7)、总有机碳(X8)、全氮(X9)、可溶性有机碳(X10)、可溶性有机氮(X11)、微生物量碳(X12)、微生物量氮(X13)、土壤呼吸速率(X14)、蔗糖酶(X15)、脲酶(X16)、过氧化氢酶(X17)、碱性磷酸酶(X18)等18个反映土壤质量的物理、化学及生物学指标作为评价指标,采用因子分析方法对不同秸秆还田方式下的土壤质量进行综合评价,并对其进行聚类分析,最后利用冬小麦产量结果进行验证。结果表明:应用因子分析法可将18个土壤指标归纳为2个主因子对土壤质量进行表征,可解释的累计方差为88.583%,各处理土壤质量排列顺序为ASP>ALP>SP>LP>LM>CK,即氨化秸秆还田在土壤质量改良方面优于其它处理。聚类分析结果表明,系统聚类图将6个秸秆还田处理分为4类,分析结果与因子综合得分评价结果较为一致。从不同秸秆还田处理冬小麦产量变化来看,秸秆还田较不还田对照能显著提高冬小麦产量,氨化秸秆还田增产效果优于传统秸秆还田,其中ASP处理5个冬小麦生长季平均产量(7668 kg·hm^-2)最高,这也与土壤质量综合得分的变化趋势比较吻合。在本研究试验条件下,粉末秸秆氨化翻压还田(ASP)改良土壤质量效果最好,为最佳秸秆还田方式。

This study aimed to select an efficient straw incorporation method to accelerate the decomposition rate of crop straw and promote the growth of winter wheat in semi-arid region of Shaanxi China.To achieve this goal,a field experiment used summer maize straw was carried out during 2011-2016.There were six treatments including control treatment with no straw returning(CK),long straw returning by covering soil(LM),long straw plowed into soil(LP),powdered straw plowed into soil(SP),long-ammoniated straw plowed into soil(ALP),and powdered-ammoniated straw plowed into soil(ASP).We investigated the effect of different straw returning approaches on soil physical,chemical,and biological properties,winter wheat yield,and then used factor analysis and cluster analysis to evaluate the soil quality under different treatments.A total of 18 soil indexes including soil bulk density(X1),soil saturated hydraulic conductivity(X2),soil saturated water content(X3),content of aggregate>0.25 mm by wet sieving(X4),mean weight diameter(X5),geometric mean diameter(X6),the fractal dimension of soil aggregates(X7),total organic carbon(X8),total nitrogen(X9),dissolved organic carbon(X10),dissolved organic nitrogen(X11),microbial biomass carbon(X12),microbial biomass nitrogen(X13),soil respiration rate(X14),sucrase(X15),urease(X16),catalase(X17),and alkaline and phosphatase(X18)were selected.Factor analysis and minimum Euclidean distance method were employed to evaluate the overall soil fertility.Two principal factors that can be used to characterize the cumulative was 88.58%,and the order of soil quality was as follows:ASP>ALP>SP>LP>LM>CK,that is,the ammoniated straw incorporation worked better than conventional straw on improving soil quality.Cluster analysis classified 6 treatments into 4 main groups on the basis of the measured parameters,which was mostly consistent with the result of factor analysis.Compared with the control treatment,the yield of winter wheat could be significantly increased by straw incorporation,and the treatment of ammoniated straw was better than conventional straw in increasing the winter wheat yield.Among the different treatments,the 5-year mean winter wheat yield(7668 kg·hm^-2)with ASP was the highest,which was also consistent with the change trend of comprehensive score of soil quality.Under the condition of this study,the ASP treatment was the best way for straw returning to improve soil quality.