The Innovation Team of Plant Nutrition of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) simulated and evaluated the nitrogen fertilizer reduction potential of maize under the application of inhibitors, based on the DNDC model. The research results were published in the international academic journal "Journal of Cleaner Production".

Synergistic fertilizers, such as urease and nitrification inhibitors, can effectively improve the nitrogen use efficiency and reduce the loss of reactive nitrogen, which has become a hot topic in global agricultural research. At the same time, synergistic fertilizer is an important research focus of agricultural science and technology development in China's "14th Five-Year Plan". However, the long-term effect of inhibitor application on fertilizer use efficiency enhancement and emission reductions is still unclear, and the potential of chemical fertilizer application reduction still lacks systematic research. The DNDC (DeNitrification-DeComposition) model based on the process mechanism has obvious advantages in simulating the soil carbon and nitrogen cycle process, and the localized improved model can better simulate the long-term effects of urease and nitrification inhibitor application on crop yield and nitrogen loss.

Based on the fix-point field experiment with different nitrogen fertilizer management treatmentsand inhibitor addition treatments from 2015 to 2017, the study verified and improved the urea hydrolysis mechanism and parameters of the DNDC model. The results show that  the improved model improved the simulation accuracy of the maize yield and nitrogen uptake, soil temperature and moisture, soil inorganic nitrogen and N2O daily emissions compared with the unimproved model,. At the same time, the improved model significantly improved the simulation of soil ammonia volatilization. Key parameters, including the urea diffusion factor, urea hydrolysis rate, urea hydrolysis moisture factor, soil depth factor of ammonia volatilization and inhibitor efficiency, were improved.

In addition, based on the long-term simulation from 1988 to 2017, compared with surface broadcast of urea, the mixed application of urea, the hole application of urea ammonium nitrate and the addition of inhibitors reduced the amount of nitrogen fertilizer by 17-40 kg/ha while ensuring the high yield of corn. In summary, this study shows that the DNDC model can be used to study the long-term effects of inhibitor application on maize yields and nitrogen loss under climate fluctuations, as well as to determine the optimal nitrogen application rate of different inhibitors and to evaluate the nitrogen application reduction potential. This is of great significance for realization of the green and sustainable development of agriculture. At the same time, this research can be extended to nitrogen optimization management under different regional climate conditions, cropping systems and soil types, providing a theoretical basis and technical support for ensuring food security and reducing environmental risks.

Fig. 1 Comparison of measured and simulated NH3 volatilization emissions under different fertilization treatments (left panel), and the maize yield and nitrogen loss throughout the growing season in relation to nitrogen fertilizer application during 1988-2017 under different fertilization treatments (right panel)

Assistant researcher Jiang Rong, from the Institute of Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, is the first author of the paper, researcher He Ping, from the IARRP, and researcher Jingyi Yang, from the Harrow R&D Center of the Canadian Ministry of Agriculture, are the co-corresponding authors.

The research was supported by the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences (No. CAAS-ZDRW202202), the Postdoctoral International Exchange Program (No. PC20180101), the research project of the Beijing Academy of Agriculture and Forestry Sciences, and the research project of the Canadian Department of Agriculture.

[Citation method and original text link]:

Rong Jiang, Jingyi Yang*, Craig F. Drury, Brian B. Grant, Ward N. Smith, Wentian He, Daniel W. Reynolds, Ping He*. Modeling the impacts of inhibitors and fertilizer placement on maize yield and ammonia, nitrogen oxide and nitrate leaching losses in southwestern Ontario, Canada. Journal of Cleaner Production. 2023. 384, 135511.

Paper link: https://doi.org/10.1016/j.jclepro.2022.135511