基于耕作指数评价耕作措施对东北风沙土耕层土壤质量的影响

Assessment of tillage effects on soil quality for aeolian sandy soil in northeast China with tilth index

为准确评价构建风沙土合理耕层的土壤质量特征,采用聚类分析方法建立了东北风沙土耕层质量诊断最小数据集(MDS),利用最小数据集的耕作指数(TI-MDS)定量评价了耕作措施对东北风沙土农田耕层土壤质量的影响,旨在为科学选择风沙土区耕作措施提供依据。试验始于2017年,在黑龙江省杜尔伯特蒙古族自治县第一粮种场,设化肥、秸秆还田和有机肥3种施肥模式,常规、旋耕、翻耕、深翻和超深翻5种耕作方式,共15个处理。测定了玉米收获期0~20 cm耕层土壤pH值、有机质、碱解氮、有效磷、速效钾、全氮、全磷、全钾、阳离子交换量(CEC)、团聚体平均重量直径(MWD)、容重、硬度、含水量、田间持水量、孔隙度和渗透速率16项评价指标。结果表明,全量耕作指数(TI-TDS)与TI-MDS的相关系数r为0.928,Nash有效系数Ef为0.761,偏差系数Er为0.079,TI-MDS取值范围为0.26~0.85,与玉米产量呈显著正相关(r=0.767),故TI-MDS可作为定量评价土壤质量的指标。施有机肥处理土壤耕作指数达到Ⅱ级水平;秸秆还田耕作指数达到Ⅲ级水平;施化肥耕作指数达到Ⅲ级水平,这表明风沙土区施用有机肥是构建合理耕层有效培肥方式,秸秆还田对合理耕层构建效果不明显。翻耕施用有机肥耕作指数最大,为0.85,达到I级;深翻+秸秆还田和超深翻+化肥措施土壤质量严重下降,降为Ⅳ级。在风沙土区应用翻耕+有机肥措施是构建合理耕层的有效措施。

To correctly assess the soil quality of cultivated layer for Aeolian sandy soil,the clustering analysis method was used to establish the minimum data set(MDS) for quality diagnosis of Aeolian sandy soil of northeast China.The effect of tillage on cultivated layer quality for Aeolian sandy soil of northeast China was assessed with tilth index of MDS(TI-MDS).All these will provide scientific evidences for selecting tillage strategies in Aeolian sandy soil.A field experiment was set up at the first grain farm in Duerbert Mongolian Autonomous County,Heilongjiang Province,in 2017.Three fertilization treatments were chemical fertilizer,straw return and organic manure.Conventional tillage,rotary tillage,tillage,deep tillage and ultra-deep tillage were carried out at the experiment plots.At maize harvest time,pH,organic matter,available N,P and K,total N,P and K,CEC,mean weight diameter(MWD),bulk density,hardness,water content,field water capacity and soil porosity were measured.Results showed the correlation coefficient between total tilth index(TI-TDS) and TI-MDS was 0.928,Ef of Nash was 0.761,Er was 0.079.TI-MDS ranged from 0.26 to 0.85,which was positive related to maize yield,indicated that TI-MDS might quantitative assess soil quality.The TI was Ⅱ,Ⅲ and Ⅲ level in organic manure,straw return and chemical fertilizer treatments,respectively.This suggested that organic manure was an effective strategy to construct cultivated layer in Aeolian sandy soil,but not very good for straw return.The greatest TI(0.85,I level) was observed in organic manure associated with tillage.Deep tillage with straw return and ultra-deep tillage with chemical fertilizer decreased soil quality,and TI was Ⅳ level.All these indicated that organic manure application associated with tillage was benefit to construct cultivated layer in Aeolian sandy soil.The effect of tillage on soil quality of cultivated layer in Aeolian sandy soil could be effectively assessed with MDS based on clustering analysis.