Soil and Water Conservation in the Agricultural Fields of Zambia: Improvement of Soil Fertility through the Use of “Planting Basins” and Soil Amendments by Rural Communities

Abstract

This study aimed to demonstrate the potential for improving yields of maize and other crops, as well as farm income, in vulnerable rural communities through moderate use of inputs, using a conservation farming technique called “planting basins,” thereby improving food self-sufficiency. This technology improves soil fertility by adopting a low application rate of inorganic fertilizer and supplementing this with soil amendments based on animal manure and lime to improve soil nutrient levels. Nutrients and moisture both limit plant growth in semi-arid Zambia. The technique was tested with plow-layer soil samples collected from farm fields at Mungu and Chikupi. Before the addition of 100kg/ha fertilizer (N : P : K 10 : 20 : 10), 100kg/ha urea fertilizer, 300kg/ha lime and 4,000kg/ha animal manure, soil pH (H₂O) was 6.34 and 6.09 at Mungu and Chikupi, respectively, with corresponding pH (CaCl₂) values of 5.24 and 4.9 for the two sites. The pH values increased (improved) significantly (to 6.80 and 6.39 pH (H₂O) and 5.41 and 5.21 pH (CaCl₂), respectively; P=0.001) in both soils after the addition of these soil amendments. The soil moisture content also rose from 2.37 and 2.68% in Mungu and Chikupi, respectively, to 7.91 and 7.30%. Available P also increased from 4.98 to 22.55ppm at Mungu and from 4.63 to 34.11ppm at Chikupi.Total nitrogen content also increased from 0.054% to 0.095% at Mungu and from 0.049 to 0.103% at Chikupi. Soil carbon content increased from 0.804 to 1.098% at Mungu and from 0.686 to 1.120% at Chikupi. Other plant nutrients (Ca, Mg and K) also increased, and most of the increases were significant. These results demonstrate that soil improvement can be achieved with reduced inputs by rural communities.