Quantitative soil quality indexing of temperate arable management systems

Soil quality assessment can provide a practical approach for early detection of adverse influences of management practices. Our objective was to develop soil quality indices (SQI) for assessing the effects of current arable management practices on soil quality for temperate maritime soils. The study was conducted on twenty arable sites with conventional or minimum tillage and mono-cropping or crop rotation. Twenty-two soil properties were measured as potential indicators of soil quality, and those indicators that were responsive to management were considered as a total data set. Principal component analysis was used to determine a minimum data set (MDS), and four indices of soil quality were calculated using linear/non-linear scoring functions and additive/weighted additive methods. Visual evaluation of soil structure (VESS) was used to validate these indices. Total nitrogen, carbon nitrogen ratio, magnesium, aggregate size distribution, bulk density, penetration resistance and soil respiration were identified as the MDS (independent variables with r < 0.7). All four SQI differed significantly by VESS class (P < 0.05), but the linear additive index showed the best discrimination by management practices (P < 0.05). The study indicated the positive influences of minimum tillage in combination with crop rotation on soil quality in Ireland, and indicated a detrimental effect of mono-cropping. The method developed in this study can provide a practical, quantitative tool for assessing soil quality under agricultural management systems.