In agricultural production, fertilizer application is a key measure to ensure high crop yields. However, excessive or unreasonable fertilization methods often lead to the loss of large amounts of nitrogen and phosphorus nutrients into water bodies through runoff and leaching, triggering environmental problems such as lake eutrophication. Located in Yunnan, the Erhai Lake Basin (ELB) is not only an important drinking water source but also a major tobacco-growing area. In recent years, with the improvement of agricultural intensification, the nitrogen and phosphorus loads in the water bodies of the basin have gradually increased, and farmland nutrient loss has become a major challenge for local water environmental protection. Is there a fertilization method that can not only maintain crop yields and farmers' incomes but also effectively reduce nutrient pollution to water bodies?
Recently, a research team from China Agricultural University, Anhui Academy of Agricultural Sciences, Yunnan Dali Tobacco Company, and Yunnan Academy of Tobacco Agricultural Sciences conducted an in-depth study on the above issues. From 2021 to 2022, the study carried out a two-year field experiment in Sanying Town, Eryuan County, setting up four treatments: no fertilizer (CK), farmer practice of solely organic fertilizer application (FP), mineral fertilizer (MF), and a combination of organic and mineral fertilizers (OMC). It systematically compared the effects of different fertilization methods on tobacco yield, economic benefits, and nitrogen and phosphorus losses. The relevant article has been published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025664).
The study found that compared with the farmer practice of solely organic fertilizer application (FP), the combination of organic and mineral fertilizers (OMC) not only increased tobacco yield by 3.8% and total output value by 8.8% but also significantly reduced nitrogen and phosphorus losses. Specifically, the OMC treatment reduced total nitrogen (TN) runoff loss by 2.7 kg·ha^–1 and leaching loss by 21%; total phosphorus (TP) leaching loss also decreased by 17.3%. The study also pointed out that nitrogen loss was mainly in the form of nitrate nitrogen, while phosphorus was mainly lost in dissolved form in runoff and in particulate form during leaching.
Data show that changes in soil organic matter (SOM) and alkaline hydrolyzed nitrogen (AN) contents significantly affect the loss dynamics of nitrogen and phosphorus, which provides a scientific basis for carrying out regional precision fertilization in the future. In addition, the peak of nutrient loss mostly occurs in June and July, which is highly consistent with the period of heavy rainfall after fertilization, indicating that optimizing fertilization timing is also crucial.
This study provides a feasible optimized fertilization scheme for the Erhai Lake Basin and similar agricultural ecological zones, demonstrating a win-win path to reduce environmental burdens while ensuring agricultural production. The 4R nutrient management principle mentioned in the study also provides a direction for further optimizing fertilization technology.
By scientifically regulating fertilizer types, application rates, and timing, we may be gradually finding the key path to balance yield and environmental protection.