Effects of optimised innovative soil fertility and water management technologies on maize production in two contrasting soils in Harare, Zimbabwe

Poor soil fertility and fertiliser management coupled with increased frequency of mid-season droughts induced by climate change have made it difficult for urban farmers to get sustainable crop yields especially on sandy soils. Urban farmers can obtain higher crop yields if they apply the right types of fertilizer at the right rates. The use of animal manures and organic municipal wastes as fertilizers is on the increase in urban agriculture (UA). However, farmers need to know the nutrient dynamics of these organic materials to optimise nutrient uptake and ultimately crop productivity. This study will investigate maize productivity on sand and red clay soils fertilized with organic and inorganic fertilizers under conventional (CT) and zero tillage (ZT) systems with and without mulching. The study will also investigate nitrogen (N) and (P) mineralization from sewage sludge and animal (cattle, poultry and pig) manures. A green house experiment will be conducted to determine maize dry matter production at 4 weeks after germination. The goal of the project is to enhance food security to urban farmers and better prepare them to face the impacts of climate change. Preliminary results for field agronomic trials showed that zero tillage + mulch + manure treatment yielded significantly higher grain yield than other treatments for both soils (p <0.05). Poultry and pig manure treated soils produced the highest dry matter for both soils from the green house experiment (p < 0.05). Poultry manure released significantly high CO2 than other manures with sewage sludge releasing the lowest. Generally, there was net N and P mineralisation throughout the incubation period. Carbon dioxide was released linearly from the start of the experiment which corresponded to immobilisation of N. Zero tillage with mulch using a combination of organic and inorganic fertilisers has a potential to raise maize grain yield.