Intercropped alfalfa and spring wheat reduces soil alkali-salinity in the arid area of northwestern China.

Background and Aims: The intercropping has great advantages in production gain, resources use and soil quality improvement. However, the effects of perennial forage legumes intercropped with annual grain crop on soil alkali-salinity was not well revealed. This study aimed to propose a spring wheat (Triticum aestivum L.)/alfalfa (Medicago sativa L.) intercropping and reveal whether this cropping system could ameliorate soil salinity. Methods: A two-year field experiment was conducted under 3 cropping systems at 3 irrigation amounts in the inland arid area of northwestern China. The cropping systems were sole spring wheat cropping (W), 12 rows spring wheat/4 rows alfalfa intercropping (W12A4) and 8 rows spring wheat/4 rows alfalfa intercropping (W8A4), and irrigation amounts included 450 (full irrigation amount, If), 360 (moderate irrigation amount, Im) and 180 mm (low irrigation amount, Il). Results: The intercropping system, especially W8A4, could more decrease soil salinity, pH and topsoil bulk density, and increase soil water content, topsoil porosity, and Ca2+ and Mg2+ contents, compared to W. Soil electrical conductivity was positively correlated with topsoil bulk density and negatively correlated with topsoil porosity, which were enhanced by intercropping and irrigation. There was weak correlation between soil electrical conductivity and soil water content. W12A4 and W8A4 led to reduction in contents of Na+, K+, Cl−, and SO42−, while Ca2+ and Mg2+ accumulated in the soil. Conclusion: Intercropped alfalfa and spring wheat could reduce soil salinity, improve soil structure and ions balance. It was recommended that W8A4 with 360 mm irrigation could be extensively used in the arid area of northwestern China, gaining grain and forage production, and helping reduce salt accumulation. [ABSTRACT FROM AUTHOR]