基于最小数据集的黄土高原半干旱区苜蓿地土壤质量评价

Soil Quality Evaluation of Alfalfa Fields in Semi-arid Areas of the Loess Plateau Based on Minimum Data Set

通过评价不同种植年限苜蓿地土壤质量变化,可为紫花苜蓿人工草地的可持续利用和适宜种植年限的确定提供理论依据。本文以黄土高原半干旱区不同种植年限的苜蓿地为研究对象,农田为对照,测定了耕层土壤物理、化学和生物学性质的21个指标,作为全数据集(Total data set,TDS)进行描述性特征分析,并通过主成分分析、相关性分析和Norm值计算构建了土壤质量评价最小数据集(Minimum data set,MDS),运用加权综合指数法开展土壤质量评价。结果表明,长期种植苜蓿会提高土壤有机碳、全氮和可溶性碳含量,但降低了土壤水分和速效磷含量。构建的MDS包括土壤容重、全氮、速效磷、脲酶、真菌Shannon指数和真菌Chao指数;全数据集土壤质量指数(TDS-Soil quality index,TDS-SQI)与最小数据集土壤质量指数(MDS-Soil quality index,MDS-SQI)均表现为L2012>L2003>农田>L2019,且两种评价体系结果呈显著正相关(R^(2)=0.599,P<0.05),表明采用最小数据集评价苜蓿地土壤质量是可行的。土壤速效磷和全氮是影响黄土高原半干旱区苜蓿地土壤质量的主要障碍因子,可通过适当施用氮、磷肥及轮作促进区域紫花苜蓿人工草地的可持续利用。

Assessing soil quality variations in alfalfa fields across different planting years can establish a theoretical foundation for the sustainable utilization of alfalfa artificial grassland and the identification of optimal planting durations.A total of twenty-one of physical,chemical,and biological indicators were measured to evaluate the cultivated soils in the semi-arid zone of the Loess Plateau,including both alfalfa fields and farmland as control.The collected data were utilized to construct a total data set(TDS)for descriptive characterization.For soil quality evaluation,a minimum data set(MDS)was developed using principal component analysis,correlation analysis,and Norm value calculation.The weighted composite index method was the applied to conduct the soil quality evaluation.The results showed that long-term alfalfa cultivation had a profound impact on soil characteristics.Specifically,it led to a significant decrease in soil water and accessible phosphorus content,while there was a notable increase in soil organic carbon,total nitrogen,and dissolved organic carbon.The constructed MDS included soil bulk weight,total nitrogen,available phosphorus,urease,and fungus’Shannon index and Chao index.The soil quality indices,both for the total data set-soil quality index(TDS-SQI)and the minimum data set-soil quality index(MDS-SQI)were the highest in L2012,followed by L2003,Farmland,and L2019.Moreover,there was significant positive correlation(R2=0.599,P<0.05)between the two evaluation systems,suggesting the potential application of MDS approach for assessing soil quality in alfalfa fields.In conclusion,the study identified soil available phosphorus and total nitrogen as the main factors affecting soil quality in alfalfa fields in the semi-arid region of the Loess Plateau.To promote the sustainable use of local alfalfa artificial grassland,implementing crop rotation and applying nitrogen and phosphorus fertilizers in an appropriate manner are recommended strategies.