Enhancing environmental monitoring and assessment: Evaluating soil quality changes using a parametric index in smallholder farming systems

Soil quality evaluation (SQE) is a crucial component of environmental assessment and monitoring. Traditional SQE methods often rely on composite indices that may overlook changes in individual soil properties. However, effective soil degradation management requires detailed, parameter-specific insights. This study applies a Parametric Soil Quality Index (PSQI) to assess the impact of cropping systems on soil properties, quantify percentage changes, and provide actionable recommendations for improving soil health in smallholder farming systems. A total of 576 composite soil samples were collected from six plots representing different cropping practices (sesame, guinea corn, yam, maize + yam mixed cropping, maize mono-cropping, and a natural forest control) in an area under smallholder farming in Abuja, Nigeria. Chemical soil properties were analyzed using t-tests, one-way ANOVA, percentage equivalence, and percentage change to assess variations by soil depth, cropping system, and control conditions. The study demonstrates that cropping systems significantly degrade soil quality compared to natural forest controls. Cultivated plots exhibit marked declines in soil organic carbon and total nitrogen, often exceeding 50% reductions, with the most severe losses in sesame and guinea corn systems. In contrast, mixed cropping (yam + maize) better retains nutrients such as potassium and cation exchange capacity. Variations in available phosphorus, exchangeable cations, and base saturation further indicate degradation due to intensive cropping and residue removal. The PSQI quantifies these changes, revealing improvements and declines in key properties. To sustain productivity, interventions such as integrated soil fertility management, organic amendments, mixed cropping, precision farming, and agroforestry are recommended.