Landscape pattern analysis using GIS and remote sensing to diagnose soil erosion and nutrient availability in two agroecological zones of Southern Mali

Abstract

Background
Soil is a basic natural resource for the existence of life on earth, and its health is a major concern for rural livelihoods. Poor soil health is directly associated with reduced agricultural land productivity in many sub-Saharan countries, such as Mali. Agricultural land is subjected to immense degradation and the loss of important soil nutrients due to soil erosion. The objective of the study was to diagnose the spatial distribution of soil erosion and soil nutrient variations under different land use in two agroecological zones of Southern Mali using the Geographical Information System (GIS) software, the empirically derived relationship of the Revised Universal Soil Loss Equation, in-situ soil data measurement and satellite products. The soil erosion effect on agricultural land productivity was discussed to highlight the usefulness of soil and water conservation practices in Southern Mali.

Results
The results of the land use and land cover change analysis from 2015 to 2019 revealed significant area reductions in water bodies, bare land, and savanna woodland for the benefit of increased natural vegetation and agricultural land. There was significant variation in the annual soil loss under the different land use conditions. Despite recordings of the lowest soil erosion rates in the majority of the landscape (71%) as a result of field-based soil and water conservation practices, the highest rates of erosion were seen in agricultural fields, resulting in a reduction in agricultural land area and a loss of nutrients that are useful for plant growth. Spatial nutrient modelling and mapping revealed a high deficiency and significant variations (p < 0.05) in nitrogen (N), phosphorus (P), potassium (K), and carbon (C) in all land use and land cover types for the two agroecologies.

Conclusions
The study highlighted the inadequacies of existing field-based soil and water conservation practices to reduce soil erosion and improve landscape management practices. The findings of the study can inform land management planners and other development actors to strategize and prioritize landscape-based intervention practices and protect catchment areas from severe erosion for the enhanced productivity of agricultural fields.