Evaluating the effects of agricultural inputs on the soil quality of smallholdings using improved indices

Abstract Soil quality on smallholder farms is progressively declining due to inappropriate land management and agricultural inputs. Assessing soil quality at the field scale and evaluating the contributions of agricultural inputs to soil quality is therefore important in the formulation of policies and technologies for improving the land management practices of smallholders. The objectives of this study were to analyze the effects of smallholder agricultural inputs (fertilizer input, agrochemical input, organic fertilization and straw incorporation) on soil quality under three dominant planting patterns (wheat-maize, vegetable and cotton) in Quzhou County on the North China Plain. Six soil indicators (soil organic carbon, available zinc, fungal species richness, carbon pool activity, total chromium content and acid phosphatase activity) were identified as the minimum dataset (MDS). The SQI calculated using nonlinear weighted additive integration (SQI-NLWA) had the best discrimination under different planting patterns. The SQIs in the wheat-maize and vegetable systems were significantly higher than those in the cotton system. The overall spatial pattern of soil quality was related to the distribution of the planting patterns throughout the county. Organic fertilization, fertilizer input and straw incorporation increased the SQI, while agrochemical input decreased the SQI. Our study provides a quantitative tool for assessing soil quality at the field-scale and creatively analyzes the effects of smallholder agricultural inputs on soil quality. Our findings suggest that resource input and allocation determine soil quality and agricultural sustainability in smallholder-dominated agricultural systems.