Recently, the Soil Fertility and Improvement team at the Institute of Agricultural Resources and Regional Planning (IARRP), CAAS, has systematically revealed the patterns and underlying mechanisms governing nitrogen supply, loss, and storage in agricultural soils under long-term fertilization. This research was conducted using a multi-site long-term experimental platform covering different climatic zones across northern and southern China. The findings provide a scientific basis for the coordinated management of carbon and nitrogen in agricultural fields and for improving soil fertility. Related research findings have been published in prestigious international journals, including Agriculture, Ecosystems & Environment, Agronomy for Sustainable Development, and the Journal of Cleaner Production.

Based on multi-site long-term field experiments covering the cold-temperate, temperate, subtropical, and tropical zones of China. The team found that the effects of different fertilization practices on soil nitrogen supply exhibited distinct regional patterns. Compared with straw returns and chemical fertilizers, organic fertilizer application had the strongest positive effect on soil nitrogen supply, especially in acidic soils with high clay content (Fig. 1a). Regarding soil nitrogen loss, the team found that long-term application of organic fertilizers could reduce nitrogen loss. Organic fertilizers application enhanced the soil's capacity to retain inorganic nitrogen, thereby reducing the risk of nitrogen loss, particularly in high-rainfall, acidic subtropical ecosystems. The study further identified soil pH and organic carbon content as important factors influencing soil nitrogen loss (Fig. 1b). Additionally, regarding soil nitrogen storage,, the team found that long-term fertilization promoted the accumulation of microbial necromass nitrogen. Long-term straw returns and organic fertilizers application increased microbial necromass nitrogen content, with organic fertilizers having a more pronounced effect. The study further indicated that fertilizer input and soil texture are important factors influencing the accumulation of microbial necromass nitrogen (Fig. 1c).

The series of studies demonstrate that appropriately balancing the inputs of organic fertilizers, straw, and chemical inputs, while considering regional climate and soil conditions, help maximize the soil fertility-enhancing and nitrogen-retention effects of organic materials. This approach facilitates the coordinated improvement of soil fertility and the resource utilization of agricultural waste. These findings provide a scientific basis for optimizing fertilization management in China’s farmlands according to local conditions, improving soil fertility, reducing nitrogen-related environmental risks, and promoting green and sustainable agricultural development.

The series of studies was completed by the team led by researcher Zhang Wenju. They were supported by projects such as the National Key Laboratory of Efficient Utilization of Dryland and Arid Farmland in Northern China, the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences, and the National Natural Science Foundation.

A graphic shows pathways of long-term fertilization affecting soil nitrogen supply, loss and storage. 

Links:

https://doi.org/10.1016/j.agee.2023.108439

https://doi.org/10.1016/j.jclepro.2024.144123

https://doi.org/10.1016/j.agee.2023.108799

https://doi.org/10.1007/s13593-025-01006-5

https://doi.org/10.1016/j.agee.2026.110612