Acknowledgements
The present study was financially supported by the National Key Research and Development Program of China (2018YFD0800500) and the National Natural Science Foundation of China (U19A2050). The Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, the Hunan Provincial Key Laboratory of Nutrition in Common University, and the National Engineering Laboratory on Soil and Fertilizer Resources Efficient Utilization are acknowledged for providing the experimental platform. All participants of the sample collection and analysis are thanked for their efforts. Last but not least, we sincerely thank all the managers of the long-term positioning experiments station for their assistance.