AimsImproving nutrient availability and water retention is critical for sustainable maize production in semi-arid regions. This study tested whether optimizing farmyard manure (FYM) placement depth with mulching enhances water conservation, soil plant nutrients dynamics, yield, and profitability.MethodsThree experiments were conducted (i) an open-shed study measuring 20-day soil moisture loss, (ii) a 112-day incubation assessing mineral N (min-N) release, soil organic carbon (SOC), and total N (TN) at 40% and 60% relative water-holding capacity (RWHC), and (iii) two-year field trial. Treatments were control, shallow FYM (0-5 cm), deep FYM (0-10 cm), shallow FYM + Urea-N, and deep FYM + Urea-N, each with no-mulch, blue, or transparent plastic. FYM was applied at 15 t ha(-)1 and Urea-N at 60 kg N ha(-)1ResultsPlastic mulch reduced soil moisture loss by 79%. At 60% RWHC, min-N release rose 19% in FYM + Urea-N but also accelerated SOC and TN depletion compared with 40% RWHC. Both shallow and deep FYM + Urea-N released 28-32% more min-N than sole FYM. In field trials, FYM + Urea-N with mulch increased grains ear(-)1 (23%), thousand-grain weight (1.6%), and yield (88%) compared with control. N uptake rose 42% with FYM + Urea-N and 20% with mulching, while sole FYM showed 11% higher N efficiency compared with control. Transparent plastic mulch with FYM + Urea-N was most profitable (value-cost ratio 3.6).ConclusionsIntegrating FYM with Urea-N and plastic mulch improves moisture conservation, N mineralization dynamics, and yield stability, providing a high-return strategy for semi-arid smallholders.Research highlightsPlastic mulch cut soil moisture loss by up to 79% in maize cropping systems.Deep or shallow FYM + Urea-N with mulch maximized N release and yield stability.60% RWHC moisture regime optimizes N release but accelerates SOC/TN loss.Plastic mulching with FYM + Urea-N delivers 88% higher yield and economic return.PCA-SEM reveals yield gains driven by soil nutrient status and crop traits.