Effects of Biochar and Crop Rotation with Maize and Pigeon Pea on soil Phosphorous Availability in Chipata and Mambwe, Zambia

Abstract

Sub- Saharan Africa (SSA) faces significant challenges in agricultural production due to soil degradation, costly fertilizers, and reliance on precipitation. Conservation agriculture has a potential to mitigate these challenges through practices such as biochar (BC) addition and crop rotation. However, the effects of BC and crop rotation on soil phosphorus (P) availability in SSA is understudied.

This thesis will investigate the impact of BC addition and crop rotation with maize and pigeon pea (PP) on soil P availability, in the Eastern districts of Chipata and Mambwe in Zambia. Eighteen farms were selected and divided into four treatments to assess the effects on soil characteristics. Soil samples were collected and analyzed for pH, P-AL, total P, organic P, inorganic P, and oxalate extractible P, Fe and Al. The analyses showed that the soils were slightly acidic to neutral (pH = 5.39 - 7.18) and had varying P-AL concentrations (3.2 mg/kg - 480 mg/kg). Chipata exhibited higher total P, but lower P-AL compared to Mambwe, possibly attributed to differences in pH and phosphorus saturation degree (PSD).

Contrary to expectations, the study found no significant effects of BC addition or crop rotation with PP on P availability. High background levels of P-AL might have masked the potential changes. Potential removal of BC while sieving the soil samples might also have removed P from the BC samples. These findings underscore the complexity of soil nutrient dynamics in SSA and highlight the need for further research to find effective strategies for enhancing agricultural production sustainability.