Managing soils and crops for sustainable agricultural intensification in coastal saline zones

Sustainable agricultural intensification to ensure global food security requires increases in both crop yields and nitrogen (N) productivity. Together, these requirements represent a considerable challenge, especially in saline regions where the high soil sodium (Na+) content limits crop growth. An integrated soil and crop management system (ISCM) may be more successful than procedures aimed at improving only soil quality (ISM) or crop management (ICM), or current local farmers' practice for achieving sustainable intensification in coastal saline zones. In this study, we tested different management alternatives for their ability to improve soil quality, agronomic feasibility, and affordability over four harvests in a 2-yr wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system in China. The ISM treatment with added cow manure and flue gas desulfurization gypsum reduced both Na+ content and pH in the subsoil, thereby improving grain yields and N productivity. The ICM treatment (i.e., optimized plant density and N fertilizer management) also increased crop yields and N productivity. The ISCM treatment integrated procedures of the ICM and ISM treatments to achieve the best agronomic benefit by increasing yields of wheat and maize by 25.3 and 30.8%, respectively, and N productivity by 109 and 97.6%, respectively, while simultaneously improving soil quality by increasing both calcium ion (Ca2+) and soil organic carbon content, and decreasing Na+ and pH in the subsoil. All three management alternatives increased economic benefits, and the ICM treatment was most valuable over the short term.