Describing soil quality with aggregate index for Msange irrigation scheme of Tanzania

Abstract Soil quality is an important and integral aspect of soil health which is defined as the continued capacity of the soil to function as a living system within the ecosystem and land use boundaries. It refers to the capacity of soil to supply nutrients, maintain suitable biotic habitat and resist degradation. This study focuses on describing the soil quality through aggregate index termed as Soil Quality Index ( SQI ). The assessment of soil quality involves physical and chemical soil parameters along with the local climatic conditions and the experts’ opinion. The proposed aggregation method utilizes three scoring functions; ‘more is better’, ‘less is better’ and ‘optimum’ for which the score is interpreted either as very low, low, medium, high or very high. The methodology has been applied to Msange irrigation scheme which falls under semi‐arid climate conditions of Tanzania. The results show that the average SQI in the Msange irrigation scheme is 0.565 for the silt loam soil and can be classified as medium quality. In order to improve the soil quality and hence the land productivity, one should improve the organic matter contents, available water and nutrients availability to the soil. It is hoped that this study will be a baseline study on soil quality evaluation for effective agricultural practices.