Aims and methodsSustainable intensification of forage production in semiarid regions requires innovative agronomic strategies that optimize yield-quality-resource trade-offs. Addressing a critical knowledge gap, this study systematically evaluated the combined effects of three irrigation levels (I1: 30-50%; I2: 50-70%; I3: 70-90% of field capacity) and three cutting frequencies (C0: single harvest; C1: one cut prior to final harvest; C2: two cuts prior to final harvest) on forage sweet sorghum (Sorghum bicolor (L.) Moench) using an auto-weighted lysimeters experiment.ResultsIrrigation significantly boosted biomass, with I2 and I3 increasing dry matter yield by 39.6% and 103.2% over I1. Mowing frequency notably affected forage quality; C0 reduced the grading index of forage sorghum by 55.9% compared to C2. However, repeated mowing reduced water use efficiency, as C2 and C1 lowered dry matter water use efficiency by 58.6% and 41.7% versus C0. A significant irrigation-mowing interaction was found: the I2C0 regime enhanced resource use efficiency, increasing crude protein water use efficiency by 8.7% over I2C2. Crop nitrogen accumulation increased with irrigation amount, but mowing decreased partial factor productivity of applied nitrogen (PFP). I2 raised PFP by 39.3% over I1, and C0 boosted PFP by 506.1% over C2. Ultimately, I2C0 performed comparably to I3C0 while reducing total water consumption by 14.6%, and is therefore recommended for semiarid regions where water is scarce.ConclusionsOptimal performance was achieved at 50-70% FC with a single harvest at maturity which enhanced both dry matter accumulation and forage nutrition while improving water-nitrogen use efficiency.