Eleven-year soil fertility changes in Dinogeng agricultural extension area of Kgatleng District in Botswana

Abstract

This study was conducted in Dinogeng Agricultural Extension Area (DAEA) in the Kgatleng District located in the eastern part of Botswana. The objective of the study was to assess soil fertility changes over an eleven-year period (2009–2020) in the extension area. In the meantime, the Integrated Support Programme for Arable Agricultural Development (ISPAAD) was launched and is continuing. Soil test data of 18 arable-farming sites for the period after inception of ISPAAD in 2009 until 2020 was obtained from the Department of Agricultural Research Soil Analytical Laboratory and Ministry of Agriculture. Geographical coordinates of the ploughing fields were taken during field work using a Geographical Positioning System (GPS). Based on availability of information, soil reaction (pH), Organic carbon (OC) and Cation Exchange Capacity (CEC) of soils for the 18 arable-farming sites were compared with data acquired from National Soil Map of Botswana (1988), scale 1: 250 000. The results showed an average significant decline of 1.55 for soil pH (P < 0.05), 0.16 % for OC (P < 0.01) and 6.75 Cmol/kg for CEC (P < 0.01). Farming practices have however, undergone some remarkable transformation including the use of fertilizers for replacing nutrient loses. The findings from this study may be useful to guide the development of functional soil fertility management plan for Dinogeng Agricultural Extension Area.