Research on the advantages and optimal irrigation regime for maize-Cyperus esculentus intercropping system in northwestern Liaoning, China

Science-based cropping pattern and irrigation scheduling are crucial for improving the efficiency of water and land use, especially in arid and demi-arid areas. Maize is extensively cultivated in northwestern Liaoning, China, where is semi-arid area. It has been a challenge to improve the water use efficiency and income of maize planting in this area. This study conducted field experiments on the maize-Cyperus esculentus intercropping system using drip irrigation over three years in Jianping County of northwestern Liaoning. Yield, water use efficiency (WUE), land equivalent ratio (LER), interspecific competitive ability and net return were measured to compare the advantages of maize-Cyperus esculentus intercropping system with monocropping. Three treatments of irrigation regimes, rain-fed(T1), heavy control (T2), light control (T3), were applied to explore the optimal irrigation regime under the intercropping system. In 2020, the optimal yield of maize in the maize-Cyperus esculentus intercropping system was 7.1 % higher than that in the monocropping system. In 2021, the optimal yield of Cyperus esculentus in the intercropping system was 29.9 % less than that in the monocropping system. The WUE of intercropping system was 12.7 %-49.8 % higher than that of maize monocropping system. LER of three irrigation treatments under maize-Cyperus esculentus intercropping system ranged from 1.78 to 2.42. Interspecific competitive ability of three irrigation treatments under maize-Cyperus esculentus intercropping system was all greater than 0, demonstrating that maize had a higher competitive capability for light, water, and nutrients compared to Cyperus esculentus. The net income of the intercropping system in 2020 is 56,398.5 CNY·hm⁻², 182 % higher than the net income of maize monocropping (19,980 CNY·hm⁻²). The net income of the intercropping system in 2021 was 55,738.5 CNY·hm⁻², 14.5 % higher than the net income of Cyperus esculentus monocropping (48,687 CNY·hm⁻²). T3 water treatment showed the highest yield and net return. The Maize-Cyperus esculentus intercropping system could improve maize yield, improve water use efficiency and increase farmers' income, comparing with monocropping and other intercropping systems. The light control (T3) in the maize-Cyperus esculentus intercropping system is recommended for promotion in northwestern Liaoning.