Film mulching improves yield and resource efficiency in corn–sunflower intercropping systems in the Guanzhong Plain of China

Integrating film mulching (FM) with cereal–oilseed intercropping offers a promising strategy to enhance resource efficiency in the Guanzhong Plain, where climate change‐driven soil and water depletion threaten grain and edible oil production. This 2‐year field study (2021–2022) assessed the combined impact of FM and intercropping configuration on yield, water use efficiency (WUE), and nitrogen utilization in corn ( Zea mays L.)–sunflower ( Helianthus annuus L.) systems. Treatments included two mulching methods: no film mulching (NF) and FM, and four planting patterns: corn monoculture (C), sunflower monoculture (S), two rows of corn alternated with two rows of sunflower (C 2 S 2 ), and two rows of corn alternated with four rows of sunflower (C 2 S 4 ). FM significantly improved plant height, leaf area, and dry matter accumulation in both crops. It also enhanced water and nitrogen use efficiencies, particularly in the C 2 S 2 intercropping system, where WUE increased by 97.77%–101.35% and total nitrogen by 16.14%–23.66% compared to monocropping. Kernel quality also improved under FM, with significantly higher starch, protein, and oil contents than NF. The film‐mulched C 2 S 2 system achieved the highest yield (8068.59 kg ha −1 ) and economic return (36,504.33 yuan ha −1 ), representing a 25.79% increase in productivity over monoculture. These findings suggest that combining FM with a 2:2 corn–sunflower intercropping pattern significantly enhances yield, resource use efficiency, and profitability—supporting sustainable intensification in the Guanzhong Plain.