Replacing part of mineral fertilizer with organic manure may cut nitrous oxide emissions from tobacco soils
A field and laboratory study in Yunnan, China, shows that substituting 15% of mineral nitrogen fertilizer with organic manure can accelerate soil nitrogen cycling while reducing emissions of a powerful greenhouse gas.
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Effects of substituting mineral nitrogen fertilizer with organic manure on nitrogen transformations and nitrous oxide emissions from tobacco (Nicotiana tabacum L.) fields
view moreCredit: Bingxue Wang, Xiaopeng Deng, Zhonglong Wang, Bin Wang, Ruibao Wang, Yali Zhang & Zhengqin Xiong
Nitrogen fertilizer is essential for crop production, but excessive use can contribute to soil degradation, nutrient losses, and emissions of nitrous oxide, or N₂O. This greenhouse gas has a much stronger warming effect than carbon dioxide over a 100-year period.
A new study published in Nitrogen Cycling suggests that partially replacing mineral nitrogen fertilizer with organic manure could help tobacco growers maintain active soil nitrogen cycling while lowering N₂O emissions.
“Our findings show that organic manure substitution does more than simply reduce the amount of mineral fertilizer applied,” said corresponding author Zhengqin Xiong of Nanjing Agricultural University. “It reshapes the microbial processes that control how nitrogen is produced, consumed, and released from soil, creating opportunities for more climate-friendly nutrient management.”
Comparing three organic fertilizer strategies
The researchers studied tobacco fields in Qujing City, Yunnan Province, where tobacco is commonly grown in acidic red soils. These soils often contain limited organic matter and may be vulnerable to acidification, inefficient nitrogen use, and greenhouse gas losses.
Four fertilizer treatments were compared. One treatment received mineral nitrogen fertilizer alone. In the other three treatments, 15% of the mineral nitrogen input was replaced with commercial organic manure, traditional farmyard manure, or bio-organic manure containing the beneficial fungus Trichoderma viride.
After the tobacco harvest, the researchers collected soil samples and used nitrogen-15 isotope tracing to follow the movement of nitrogen through different soil pools. This approach allowed them to estimate the rates of ammonium production and consumption, nitrate production and consumption, and the contributions of different microbial pathways to N₂O formation.
Faster nitrogen cycling, but lower emissions
Compared with mineral fertilizer alone, all three organic substitution treatments increased gross nitrate production, ammonium production, and ammonium consumption.
Autotrophic nitrification, a microbial process that converts ammonium into nitrate, was the main contributor to both nitrate production and ammonium consumption. It was especially active in soils receiving farmyard manure and bio-organic manure.
Despite this greater nitrogen transformation activity, the organic substitution treatments produced significantly less cumulative N₂O than the mineral fertilizer treatment. Among the treatments, cumulative emissions followed the order of mineral fertilizer, farmyard manure, commercial organic manure, and bio-organic manure, although the differences among the three organic treatments were not statistically significant.
The isotope analysis showed that autotrophic nitrification remained the largest source of N₂O, accounting for about 60% to 67% of total emissions across the treatments. However, replacing part of the mineral fertilizer with organic manure reduced the amount of N₂O generated through this pathway.
Bio-organic manure showed particular benefits
The bio-organic manure treatment produced the highest ammonium production and nitrate consumption rates. It also resulted in the lowest cumulative N₂O emissions in the experiment.
The researchers suggest that bio-organic manure may improve soil structure, aeration, carbon availability, and microbial activity. These changes can support rapid nitrogen cycling while reducing the proportion of nitrogen lost as N₂O.
The study also found that organic substitution altered the abundance of microbial genes involved in nitrification and denitrification, helping explain why different manure types affected nitrogen processes in different ways.
Implications for climate-smart fertilizer management
The authors note that the isotope incubation used a relatively high tracer addition to ensure accurate measurements. Therefore, the reported transformation rates should be interpreted as potential rates under controlled conditions rather than exact field rates.
Even so, the comparison among treatments provides clear evidence that partial organic substitution can improve soil nitrogen dynamics and reduce N₂O emissions from tobacco-growing soils.
The findings offer practical support for fertilizer strategies that reduce reliance on mineral nitrogen, improve soil quality, and contribute to agricultural greenhouse gas mitigation.
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Journal Reference: Wang B, Deng X, Wang Z, Wang B, Wang R, et al. 2026. Effects of substituting mineral nitrogen fertilizer with organic manure on nitrogen transformations and nitrous oxide emissions from tobacco (Nicotiana tabacum L.) fields. Nitrogen Cycling 2: e021 doi: 10.48130/nc-0026-0008
https://www.maxapress.com/article/doi/10.48130/nc-0026-0008
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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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Journal
Nitrogen Cycling
Method of Research
Experimental study
Article Title
Effects of substituting mineral nitrogen fertilizer with organic manure on nitrogen transformations and nitrous oxide emissions from tobacco (Nicotiana tabacum L.) fields
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