Selection basis of forage sorghum production system: Assessment of the effects of cutting period and irrigation amount on productivity and resource efficiency

Cutting and irrigation are effective measures to improve crop production and resource utilization. However, further research is still needed to explore the synergistic effect of cutting period and irrigation amount on yield enhancement and efficient resource use to exploit sorghum’s regrowth potential in arid regions. A two-year field experiment (2024–2025), including three cutting periods (A1: 75 days after sowing; A2: 90 days after sowing; A3: 105 days after sowing) and three irrigation amounts (B1: 60 mm; B2: 90 mm; B3: 120 mm), with an additional non-cutting treatment under normal irrigation (90 mm)(CK) was conducted in the Northwestern of China. Results showed that adjusting cutting period and irrigation amount could optimize forage sorghum canopy development to enhance the productivity and resource utilization ( P < 0.05). Early cutting (A1) minimized yield reduction (6–12 %) and achieved the highest RUE (up to 2.09 g MJ⁻¹), while mid-term cutting (A2) combined with increased irrigation (120 mm) produced the greatest water productivity of dry matter yield (WP DM ) (44.1 kg ha⁻¹ mm⁻¹) and balanced yield performance (12.9 t ha⁻¹). In contrast, late cutting (A3) consistently resulted in the lowest efficiency (WP DM 28.5–28.8 kg ha⁻¹ mm⁻¹) particularly under increased irrigation. Surface fitting analysis further indicated that maximum DM was achieved under mid or late cutting with normal or increased irrigation, whereas the maximum WP DM and RUE concentrating in early cutting with reduced irrigation. These findings highlight the trade-offs between yield stability and efficiency optimization, suggesting that early cutting is preferable for efficiency-oriented production, while mid-term cutting with increased irrigation optimizes both yield and resource use. This study provides scientific basis for tailoring cutting period and irrigation amount of forage sorghum, offering practical guidance for sustainable forage-livestock systems in the Northwest of China. • Early cutting decreased yield reduction (6–12 %) as well as obtaining the highest RUE up to 2.09 g MJ⁻¹ . • Early cutting favors efficiency-oriented production, whereas mid-term cutting with higher irrigation balances yield and resource use.