Enhancing water use efficiency and nutritional quality of maize fodder under deficit irrigation with microbial and potassium amendments

Optimizing maize fodder production under water limited conditions is essential for sustainable livestock systems facing climate induced water stress and declining soil fertility. In this two-year field study, we investigated how deficit irrigation at different maize growth stages (VT-R3, R3-R6, VE-VT) in combination with potassium fertilization (0, 50 kg ha⁻¹) and bacteria inoculation (B-, B+) influences water use efficiency and the nutritional quality of maize fodder. Data was recorded on acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), ash, hemicellulose, biological yield, water use efficiency and irrigation water use efficiency. Irrigation timing exerted the strongest influence on most traits. Late season deficit irrigation (R3-R6) increased fiber accumulation (ADF and NDF), whereas early season deficit irrigation (VE-VT) consistently reduced fiber accumulation while improving crude protein content and irrigation water use efficiency. Full irrigation produced the highest biological yield, followed by early season deficit irrigation. Potassium fertilization enhanced crude protein content and water use efficiency, particularly under water limited conditions. Bacterial inoculation significantly improved crude protein concentration, biological yield, and both water use efficiency and irrigation water use efficiency, with more pronounced effects under deficit irrigation. Overall, the results indicate that early season deficit irrigation (VE-VT) combined with potassium supplementation and bacterial inoculation represents an effective integrated strategy to improve forage biomass production and water productivity in maize; however, these practices may also increase fiber fractions, potentially reducing digestibility and voluntary intake, and therefore require careful balancing of yield gains with forage quality.