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The cadmium (Cd) activity in soil has been widely studied. However, the interactive effects of soil properties (e.g. soil pH, CEC, and SOM) on Cd transfer from soil to grain are generally overlooked. In total 325 datasets including soil pH, CEC, SOM, and soil Cd content were used in this study. The descriptive statistics indicated that Cd content in wheat and maize soils ranged from 0.05 to 10.31 mg/kg and 0.02–13.68 mg/kg, with mean values of 0.87 and 1.14 mg/kg, respectively. Cd contents in wheat and maize grains were 0.01–1.36 mg/kg and 0.001–1.08 mg/kg with average values of 0.15 and 0.10 mg/kg, respectively. The results of SEM demonstrated that the interactive effects of soil properties contributed more to Cd transfer from soil to wheat grain than the soil Cd content. Subsequently, CITs-MLR indicated that the critical factors, including soil pH and total soil Cd content, could mask the contribution of other soil properties on Cd accumulation in grain; soil CEC may prevent Cd from leaching and therefore improve grain Cd level of wheat especially at acidic soil condition. The result of derived Cd thresholds revealed that current Cd thresholds are not completely suitable to wheat and maize grain at different soil conditions. This study provides a new model for further investigation on relationships between soil properties, soil Cd content and grain Cd level. Image 1 • The interactions of soil properties influence Cd transfer in a higher degree than soil Cd content. • Soil pH may mask other soil properties' contribution on Cd transfer. • Diverse Cd thresholds for different soil conditions are obtained. [ABSTRACT FROM AUTHOR]

Numerous strategies for mitigating ammonia volatilization (AV) from agricultural land have been investigated with limited evaluation of their efficacy and response to differing field conditions across China. Therefore, this meta-analysis seeks to draw conclusions about AV in China, and assess the effect of crop type (wheat, maize, and rice as staple crops), climatic conditions, and soil properties on AV and variations in responses that can guide selection of appropriate strategies under different conditions. Novel analysis indicates nitrogen (NH 3 –N) losses of 7.62 Tg due to AV from these three crops in China. AV is 12.8 and 18.0% (95% CI) higher from maize than from wheat and rice, respectively, without N application under warm and sub-humid conditions (MM), and 13.8 and 2.8% higher under hot and humid conditions (HH). AV increases notably under HH as compared with cold and sub-arid conditions (LL) by 11.5% and 28.4% under the control treatment and application of 150 kg N ha−1, respectively in rice fields while it is most substantially under maize (52.5%) with application of 150 kg N ha−1. The ratio of change in AV between soil grades 3 and 1 (potential AV >1.0 and < 0 cmol kg−1) is significantly greater for wheat and rice (2.5%) than for maize (1.9%). The strategy of reducing N rate is more effective for maize and rice than wheat, where applying N at a rate of 150–220 kg N ha−1 to them has similar effects to applying 300 kg N ha−1 to wheat. For wheat and maize, urea should be partially substituted with organic amendments, while improved urea is the preferable N source for rice. Subsurface application has competitive efficacy, especially for maize, and higher N rates. Applying inhibitors achieves the highest AV reduction, especially with rice under various conditions, creating more actively options for future research to increase applicability. Image 1 • About 7.62 Tg N–NH 3 from main staple crops in China was indicated using CMA outputs. • Higher AV from maize fields than wheat and rice by (95% CI = 12.8 and 18%) even without N applications. • AV under maize and rice is higher under warm-humid conditions than cold-dry but wheat showed reverse response. • Improved urea and inhibitor usage is optimum strategy in reducing AV especially under rice. • Organic amendments, mulching and subsurface application are efficient strategies in reducing AV for wheat and maize. [ABSTRACT FROM AUTHOR]