Innovative Field Study Reveals Effective Method to Reduce Nitrogen Pollution in Tea Plantations

A groundbreaking field experiment carried out over two years in subtropical central China demonstrates a promising advancement in the quest for sustainable agriculture: specifically, the integration of dual nitrogen transformation inhibitors with biochar amendments in tea cultivation to mitigate environmentally harmful nitrogen emissions without compromising yields. This study addresses a critical challenge faced by tea producers worldwide—balancing ammonia and nitrous oxide emissions, both potent agents of environmental degradation, with the need for maintaining high agricultural productivity.

Tea, one of the most consumed beverages globally, often demands intense nitrogen fertilization to achieve optimal yields. However, conventional nitrogen fertilizer application frequently leads to excessive nitrogen losses through gaseous emissions, particularly nitrous oxide (N₂O) and ammonia (NH₃). Nitrous oxide is a significant greenhouse gas with a global warming potential approximately 300 times that of carbon dioxide, while ammonia emissions contribute to atmospheric particulate matter formation and ecological nutrient imbalances. Thus, reducing these emissions is imperative for both climate change mitigation and ecosystem preservation.

In the recently published research in the journal Biochar, scientists investigated the effects of dual nitrogen inhibitors alongside biochar amendment on nitrogen gas emissions in a subtropical tea plantation in Hunan Province. The inhibitors studied were NBPT (N-(n-butyl) thiophosphoric triamide), an agent that impedes urease-mediated urea hydrolysis, thereby reducing ammonium volatilization; and DMPP (3,4-dimethylpyrazole phosphate), a nitrification inhibitor that slows the microbial conversion of ammonium to nitrate, effectively curbing nitrous oxide production resulting from nitrification and denitrification processes.

The experimental design compared four treatment groups: a control with no nitrogen fertilization; a conventional fertilization regime; a reduced nitrogen fertilizer application supplemented with both inhibitors; and a reduced nitrogen fertilizer combined with dual inhibitors as well as biochar addition. These comparative treatments allowed for a nuanced assessment of how integrated nutrient management practices influence gaseous nitrogen emissions and tea plant performance.

Analyses revealed that conventional nitrogen fertilization induced substantial nitrogen losses, averaging 25.8 kilograms per hectare of N₂O and 75.8 kilograms per hectare of NH₃ over the study period. Remarkably, the application of NBPT and DMPP inhibitors reduced nitrous oxide emissions by 54.5% and ammonia emissions by 20.0%. The further integration of biochar with these inhibitors maintained similar reductions—49.8% for N₂O and 20.2% for NH₃—indicating that while biochar did not enhance nitrous oxide mitigation beyond inhibitors alone, it played a critical role in improving nitrogen use efficiency.

Biochar, a carbon-rich porous material derived from biomass pyrolysis under oxygen-limited conditions, has garnered attention for its capacity to enhance soil physical and chemical properties. Here, its incorporation was associated with a 6.7% increase in tea yield and a 14.4% enhancement in total plant nitrogen uptake. This suggests biochar fosters improved nutrient retention and availability, augmenting crop productivity alongside environmental benefits.

Spatial analysis within the tea plantation revealed that nitrogenous gas emissions were predominantly emanating from the fertilized tea rows rather than the inter-row ridges, underscoring the importance of targeted fertilization strategies. This spatial differentiation in emission sources may enable more precise application of inhibitors and soil amendments, maximizing environmental gains while minimizing input costs.

At the microbial level, the study highlighted shifts in the abundance of genes integral to soil nitrogen cycling. Soil treated with inhibitors exhibited decreased populations of ammonia-oxidizing bacteria and reduced expression of the nitrite reductase gene nirS, a marker for denitrifying bacteria responsible for N₂O production. Such microbial population changes underpin the observed suppression of nitrification and denitrification pathways, thereby elucidating the biochemical mechanisms mediating emission reductions.

The findings underscore the potential for integrated management strategies leveraging biochemical inhibitors and soil amendments to promote climate-smart agriculture. By attenuating nitrogenous greenhouse gas emissions and enhancing nitrogen uptake efficiency, these approaches offer dual environmental and agronomic benefits. Notably, the enhanced tea yield observed with biochar integration highlights a synergistic effect that aligns ecological stewardship with economic viability for farmers.

Despite these promising outcomes, the authors urge caution in generalizing results across diverse agroecosystems and climatic zones. Variations in soil texture, climate conditions, fertilizer regimes, and management practices can influence inhibitor and biochar efficacy. Consequently, long-term, multi-site evaluations are necessary to optimize application protocols and fully characterize the sustainability potential of these interventions in tea and other crop production systems.

In conclusion, this pioneering study provides compelling field-based evidence supporting the deployment of dual nitrogen inhibitors in concert with biochar amendments as a practical and scalable solution to reconcile agricultural productivity with environmental conservation in subtropical tea cultivation. As agriculture faces mounting pressures to reduce its ecological footprint, innovations such as these illustrate the path toward resilient and responsible food production.

News Publication Date: 16-Jun-2026

Web References: http://dx.doi.org/10.1007/s42773-026-00635-7

References: Li, Y., Li, Y., Zhang, H. et al. Reduction in N2O and NH3 emissions with combined use of dual inhibitors and biochar in a tea field soil in subtropical central China. Biochar 8, 114 (2026).

Keywords

Nitrous oxide emissions, ammonia volatilization, nitrogen inhibitors, biochar, tea cultivation, sustainable agriculture, nitrogen cycling, microbial nitrification, denitrification, subtropical agriculture, greenhouse gas mitigation, nutrient use efficiency