Enhancing Phosphorus Deficient Soils for Maize Production: The Role of Biological Nitrogen Fixation in Doubled up Legume Systems

Legumes improve soil fertility through biological nitrogen fixation (BNF). However, their performance is also dependant on the initial fertility status of the soil. Phosphorus is one of the key nutrients for legume performance. Most of the soils in Africa, including Malawi, are deficient in phosphorus. A study was conducted on twenty smallholder farms in Malawi in 2019/20 and 2020/21 rainy seasons to determine how BNF in groundnut (Arachis hypogaea) and pigeon pea (Cajanus cajan) can be improved in phosphorus deficient soils for subsequent maize production. The study was done in two sites namely Kasungu (Site 1) and Mzimba (Site 2). Site 1 is a mid-altitude while site 2 is in high altitude agroecological zone. Soils in both sites are slightly acidic (pH 4.9 – 5.0 in water), with low organic matter (