The Soil Fertility and Improvement Innovation Team at the Institute of Agricultural Resources and Regional Planning, part of the Chinese Academy of Agricultural Sciences (CAAS) has made significant progress in improving sandy soils. By analyzing global data from long-term amendment experiments, the research team assessed the effects of organic and inorganic amendments on soil organic carbon (SOC) and crop yields, uncovering the role of aridity in the relationship between crop productivity and SOC sequestration. Their findings were published in the international journal Geoderma. Sandy soils, covering approximately 7% of the Earth's land surface, and including around 200 million hectares of farmland, are common in arid and semi-arid regions. These soils suffer from low clay and organic content, poor water and nutrient retention, and are vulnerable to erosion and drought, which hampers agricultural productivity. Applying soil amendments, like organic fertilizers, biochar, and bentonite, can effectively improve soil fertility and support sustainable agriculture, though their efficacy varies with climate, management, and soil characteristics.

A global meta-analysis based on 843 observations from 151 field-based studies was conducted to evaluate the patterns and key controlling factors of crop yield and its linkage with SOC in response to organic and inorganic amendments into sandy soil. Results showed that amendment application strongly increased crop yield by 39% and SOC by 62% on average in sandy soils, with the greatest yield increase by composite amendments (+92%), followed by inorganic amendments (+62%) and organic amendments (+36%). The inorganic amendment led to the highest increase in SOC (+133%), followed by composite (+59%) and organic amendments (+48%). The linkage between the responses of crop yield and SOC was climate-dependent, with a strongly positive correlation in humid regions (aridity index <0.5), while no significant relationship was observed in arid regions. The crop yield response positively correlated with mean annual temperature, amendment amount, and initial contents of soil sand and SOC, but decreased with aridity index, amendment duration and soil pH. Random forest analysis revealed that climate (aridity index) and soil properties (initial SOC and pH) were key factors regulating crop yield response, collectively explaining 48% of the variation. Moreover, aridity index was the key driver indirectly affecting crop yield response via regulating SOC and nutrient availability. Crop yield increase by amendment application was significantly larger (50-56%) under humid regions with high SOC relative to cold and arid regions with low SOC (30-35%). 

The study emphasizes that site-specific strategies should be developed according to regional aridity and soil physicochemical properties to achieve synergistic and sustained improvements in both carbon sequestration and agricultural productivity in sandy soils.

The paper's first author is Liu Tianhong, a joint master's student of Hainan University and CAAS, and the corresponding author is Dr. Wu Lei, Associate Researcher at CAAS. The research was jointly supported by the National Key Laboratory of Efficient Utilization of Arid and Semi-Arid Farmland, the Major Science and Technology Project of Xinjiang Uygur Autonomous Region, and the CAAS Young Scientist Innovation Program.

Citation:

Liu, T., Wu, L., Tang, S., Shaaban, M., Meng, L., Xu, M., & Zhang, W. (2025). Positive effects of amendments on crop yield and organic carbon in sandy soils are regulated by aridity: A global meta-analysis. Geoderma, 462, 117540.

DOI: https://doi.org/10.1016/j.geoderma.2025.117540