Benefits and Risks for the Environment and Crop Production with Application of Nitrification Inhibitors in China

Positive and negative effects coexist in applying nitrification inhibitors (NIs) in China, making it difficult to accurately evaluate the risks and benefits brought by applying NIs. Thus, this study comprehensively investigated the benefits and risks for the environment and crops when applying three commonly used NIs: 3,4-dimethypyrazole phosphate (DMPP), dicyandiamide (DCD), and 2-chloro-6-trichloromethyl pyridine (nitrapyrin) in China. A meta-analysis including 617 observations from 172 studies in China was conducted in this study. DMPP, DCD, and nitrapyrin averagely reduced nitrous (N2O) emissions by 60.1%, 30.4%, and 36.1%, nitrate (NO3-) leaching by 49.5%, 51.9%, and 49.4%, respectively. Methane (CH4) and carbon dioxide (CO2) emissions were also inhibited by NIs. However, the application of DMPP, DCD, and nitrapyrin aggravated ammonia (NH3) volatilization by 43.2%, 27.4%, and 28.5%, respectively, and ammonium (NH4+) leaching by an average of 28.2%, 80.1%, and 30.9%, respectively. NIs increased crop yields and the magnitudes of the effects were in the following order: nitrapyrin (8.6-12%) > DCD (6.9-10.3%) > DMPP (5.8-8%). Furthermore, plant NO3- content was reduced by NIs and crop growth characteristics and qualities (e.g., plant height and sugar content) all exhibited positive responses to NI application. NI application provided benefits by decreasing N2O, CH4, and CO2 emissions and NO3--N leaching and by enhancing crop yields and quality. The risks of NI application were caused by increasing NH3 volatilization and NH4+-N leaching. Considering all the environmental and crop factors together, the benefits in applying NIs were greater than the risks.

Automated summary

This study found that while NIs can reduce nitrogen oxide emissions and nitrate leaching, they can also increase ammonia volatilization and ammonium leaching. NIs have a positive impact on crop yield and crop quality, promoting plant growth and improving quality significantly.