Management strategies for improving maize yield and water productivity under water deficit and soil acidity

Summary Maize holds a key role in ensuring food security in Ethiopia, yet its productivity faces challenges due to water scarcity and soil acidity. Minimizing these problems is crucial to enhance maize yield and maintain food security. This research explored the effects of deficit irrigation (DI) combined with lime, manure, and inorganic fertilizer application on maize yield and water productivity (WP) in Koga, Ethiopia. Three levels of DI, namely 80%, 60%, and 50% of crop evapotranspiration (ETc), alongside 100% ETc (full irrigation) as a reference, were implemented for two consecutive seasons. Five integrated soil fertility management (ISFM) treatments were evaluated over two successive seasons: (i) combining 1.43 Mg ha–1 of lime with 3 Mg ha–1 of manure and full doses of urea + (NPSB, containing 18.9% Nitrogen, 37.7% Phosphorus, 6.95% Sulphur, and 0.1% Boron), referred to as inorganic fertilizer (L1); (ii) combining 1.15 Mg ha–1 of lime with 3 Mg ha–1 of manure and full doses of inorganic fertilizer (L2); (iii) combining 0.86 Mg ha–1 of lime with 3 Mg ha–1 of manure and full doses of inorganic fertilizer (L3); (iv) applying 3 Mg ha–1 of manure and full doses of inorganic fertilizer (M); and (v) using only full doses of inorganic fertilizer (C). Grain yield and biomass were measured at harvest from a 9 m2 sample area in each plot, with three replicates. The combined effects of DI, liming and manuring significantly influenced average grain yield and biomass. Across all irrigation scenarios, higher grain yield and biomass production were found with treatments L1, L2, L3, and M compared to treatment C. The highest WP was found with 50% ETc under all ISFM treatments. The lowest maize yield and WP were recorded with treatment C across all irrigation levels. Manuring combined with reduced irrigation increased grain yield, biomass, and WP compared to the use of inorganic fertilizer alone at 100% ETc. The combined use of lime and manure could mitigate the negative impact of DI on yield.