基于土壤肥力质量综合指数评价化肥与有机肥配施对红壤稻田肥力的提升作用

  【目的】  准确评价有机肥料提高农田土壤肥力的效果，是正确选择土壤培肥措施的基础。通过比较两种土壤肥力质量综合指数的计算方法评价有机肥培肥效果的可行性。  【方法】  3年田间定位试验 (2015—2017) 在长江中下游的红壤双季稻田进行。共设7个处理:不施肥 (CK)，等氮磷钾投入量下的单施化肥 (CF) 和一半化肥氮配施一半的牛粪 (+CM)、猪粪 (+PM)、鸡粪 (+ChM)、绿肥 (+GM) 与秸秆 (+SR)。在2017年晚稻收获后，采集耕层土壤样品，分析土壤理化性状和土壤生物学性状。筛选用于评价土壤肥力的指标，用雷达图分析稻田土壤肥力水平的制约因素，采用土壤肥力质量综合指数 (IFI) 评价不同有机肥料的培肥效果。  【结果】  1) 团聚体结构、pH、有机质3个指标属于弱变异性，其余指标属于中等强度变异，以有效锌、有效磷以及酸性磷酸酶的变异系数较大，对施肥处理的响应比较灵敏；2) 由隶属度值制成的雷达图显示，土壤阳离子交换量 (CEC)、速效钾与全磷含量是制约稻田土壤肥力水平最主要的3个因子；3) 运用全量数据集与最小数据集计算的肥力指数IFI均表明，相对于不施肥CK，6个施肥处理均可以显著提高土壤肥力指数IFI，5个有机无机肥配施处理的IFI均显著高于单施化肥处理，且+PM与+ChM处理的IFI指数显著高于+CM与+GM处理；在全量数据集下，+SR处理的IFI指数显著高于+CM与+GM处理，而在最小数据集下，3个处理间差异不显著；4) 全量数据集的土壤肥力质量综合指数IFI_TDS和最小数据集的土壤肥力质量综合指数IFI_MDS均与双季稻总产量呈极显著正相关关系。  【结论】  基于全量数据集和基于最小数据集的土壤肥力质量综合指数 (IFI_TDS、IFI_MDS) 均可客观表征土壤肥力质量。依据该指标，化肥配施猪粪提高土壤肥力的效果最佳，其次是配施鸡粪或秸秆，最低是配施牛粪或紫云英绿肥。

Evaluating soil fertility improvement effects of chemical fertilizer combined with organic fertilizers in a red paddy soil using the soil fertility index

  【Objectives】  Correct evaluation of soil fertility is the base of choosing efficient management method for improving soil fertility. This study investigated the soil fertility via total dataset (IFI_TDS) and minimum dataset (IFI_MDS).  【Methods】  A three-year (2015–2017) field experiment was conducted in a paddy soil derived from red earth in middle and lower reaches of the Yangtze River. Seven treatments in the field included: no fertilizer (CK), sole chemical NPK fertilizer (CF) and treatments that replaced half NPK input levels by cattle manure (+CM), pig manure (+PM), chicken manure (+ChM), milk vetch manure (+GM) or straw incorporation (+SR). After harvesting of late rice in 2017, top soil samples were collected for the determination of physical, chemical and biological property indicators. The indicators closely related to rice yield were screened, and the main limiting factors in soil fertility quality were investigated by radar plotting. The soil integrated fertility index (IFI) under each organic fertilizer treatment was assessed.  【Results】  The soil aggregates, pH and OM (organic matter) belonged to weakly variable fertility factors (CV < 10%), while other soil properties belonged to moderate variable fertility factors (10% < CV < 100%). Among the moderately factors, available Zn, available P and acid phosphatase activity were relatively sensitive to fertilization. According to the Radar plot of membership, cation exchange capacity (CEC), readily available K and total P were the major constraints for soil fertility. The soil fertility index based on total data set (IFI_TDS) and that based on minimum data set (IFI_MDS) showed similar evaluation result on the soil fertility of fertilizer treatments. Both the IFI_TDS and IFI_MDS in +PM and +ChM treatments were significantly higher than those in +CM and +GM treatments. The IFI_TDS of +SR treatment was significantly higher than those of +CM and +GM treatments, but IFI_MDS did not differ among the three replacement treatments. Both the values of IFI_TDS and IFI_MDS were significantly related with rice yield.  【Conclusions】  Both the IFI_TDS based on total dataset and IFI_MDS based on minimum dataset can objectively reflect soil fertility. According to the IFI_TDS and IFI_MDS of soils under each treatment, chemical NPK fertilizer combined with pig manure has the best soil fertility improvement effect, followed by the treatment with chicken manure and straw incorporation, while treatments with cattle manure and milk vetch manure have the weakest effects.