Smallholders crop production systems in Africa are constrained by a variety of factors: among them nutrient deficiency and low soil organic matter status. Groundnut (iArachis hypogea L/i) production in these areas is usually practiced with no artificial fertilisers or cattle manure as fertilizers are preferably used for staple crops production like maize. Organic composts from municipal landfills provide an alternative source of organic amendment for peri-urban groundnut production. Greenhouse and field studies were conducted during the 2010-11 season to determine whether municipal phosphocomposts can increase groundnut productivity as measured by dry matter, P uptake and yield. The field studies were carried out at two sites, namely Africa University farm and Nyamazura, both in Manicaland province of Zimbabwe. The studies were carried out during the 2010/2011 seasons. Municipal phosphocomposts used in the experiment were made from sewage sludge (SL), vegetable vending waste (VW) and wood processing waste (WW) collected from various sites in the city of Mutare. The wastes were composted with Zimbabwe (Dorowa) phosphate rock (DPR) and sulphur for a period of 56 days before being used for the experiments. Application of the three-municipal organic phosphocomposts produced comparable dry matter with inorganic fertilisers (SSP). Addition of sewage sludge/DPR composts improved dry matter of groundnuts. Leaf P and residual Psub2/subOsub5/sub were significantly (P0.05) higher with organic amendments than with other soil ameliorants, except for SSP. The amount of residual phosphorous from sewage sludge compost amended plots was enough to support a succeeding crop of maize (30 ppm resin extractable). Municipal composts significantly (P0.001) improved groundnut pod yield compared to control and sole DPR. The study showed that the use of municipal phosphocompost is beneficial in improving groundnut nutrition and productivity. They can therefore be used for groundnut production in areas where soil nutrient sources are scarce and have potential for building phosphorous stocks. Apart from increasing current crop growth, the composts can also help build soil organic matter.
Muziri et al. (Wed,) studied this question.