Nitrification inhibitor outperforms biochar in boosting crop yields and cutting greenhouse gas emissions in alkaline soils

Farmers around the world rely on nitrogen fertilizers to sustain crop production, but in many alkaline soils a large share of that nitrogen is rapidly lost before plants can use it. A new study published in Nitrogen Cycling finds that a widely used nitrification inhibitor can dramatically improve fertilizer efficiency and crop yields while sharply reducing emissions of nitrous oxide, a powerful greenhouse gas.

The research compares the performance of biochar and the nitrification inhibitor 3,4-dimethylpyrazole phosphate, known as DMPP, in calcareous soils. These soils, common in arid and semi-arid regions of Asia, the Mediterranean, North Africa, and Australia, have high pH levels that accelerate nitrogen transformations and losses.

“Our results show that DMPP was consistently more effective than biochar at stabilizing nitrogen in calcareous soils,” said Tongbin Zhu, corresponding author of the study. “This translated directly into higher nitrogen use efficiency, greater crop yields, and much lower nitrous oxide emissions.”

The research team conducted two consecutive growing seasons of controlled pot experiments using pak choi, a widely cultivated leafy vegetable. Eight fertilizer treatments were tested, including standard nitrogen, phosphorus, and potassium fertilizers, fertilizers combined with biochar at low and high application rates, DMPP alone, and combinations of biochar and DMPP.

Across both growing seasons, DMPP increased crop nitrogen uptake by up to 49 percent and boosted yields by as much as 49 percent compared with conventional fertilization. Nitrogen use efficiency improved by up to 18 percent. Most strikingly, cumulative nitrous oxide emissions were reduced by 77 to 85 percent.

Nitrous oxide is a greenhouse gas with nearly 300 times the global warming potential of carbon dioxide and is a major contributor to climate change from agriculture.

“Reducing nitrous oxide emissions while maintaining or increasing yields is one of the biggest challenges in sustainable agriculture,” Zhu said. “DMPP offers a practical solution for farmers working with alkaline soils.”

By contrast, biochar did not deliver the expected benefits in this soil type. While biochar increased microbial nitrogen immobilization, it also accelerated nitrification, reduced nitrogen use efficiency, and stimulated nitrous oxide emissions, particularly at higher application rates. Even when biochar was combined with DMPP, it did not enhance the inhibitor’s effectiveness.

To understand why these differences occurred, the researchers measured key nitrogen transformation processes in the soil. DMPP strongly suppressed the activity of ammonia-oxidizing bacteria, reducing nitrification rates by more than 50 percent and keeping nitrogen in forms that crops could access for longer periods. This prolonged nitrogen residence time allowed plants to absorb more fertilizer nitrogen before it was lost to the environment.

“Biochar is often promoted as a universal soil amendment,” Zhu said. “Our findings show that its effects depend strongly on soil type and application rate. In calcareous soils, biochar alone may not be the best strategy for improving nitrogen efficiency.”

The authors emphasize that their results do not diminish the value of biochar in other soil systems, but underline the importance of precision nitrogen management strategies tailored to specific soil conditions.

“Choosing the right nitrogen management approach is critical for both food security and climate mitigation,” Zhu said. “For calcareous soils, nitrification inhibitors like DMPP provide a more reliable pathway toward sustainable crop production.”

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Journal Reference: Liu L, Ding N, Meng L, Xu Q, Zhu T, et al. 2026. Nitrification inhibitor enhances nitrogen use efficiency and crop yield more than biochar in calcareous soils. Nitrogen Cycling 2: e001  

https://www.maxapress.com/article/doi/10.48130/nc-0025-0013 

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About Nitrogen Cycling:
Nitrogen Cycling (e-ISSN 3069-8111) is a multidisciplinary platform for communicating advances in fundamental and applied research on the nitrogen cycle. It is dedicated to serving as an innovative, efficient, and professional platform for researchers in the field of nitrogen cycling worldwide to deliver findings from this rapidly expanding field of science.

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