How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input

Abstract

Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have doubled global annual reactive N inputs in the past 50-100 years, causing deleterious effects on the environment through increased N leaching and nitrous oxide (N2 O) and ammonia (NH3 ) emissions. Leaching and gaseous losses of N are greatly controlled by the net rate of microbial nitrification. Extensive experiments have been conducted to develop ways to inhibit this process through use of nitrification inhibitors (NI) in combination with fertilizers. Yet, no study has comprehensively assessed how inhibiting nitrification affects both hydrologic and gaseous losses of N and plant nitrogen use efficiency. We synthesized the results of 62 NI field studies and evaluated how NI application altered N cycle and ecosystem services in N-enriched systems. Our results showed that inhibiting nitrification by NI application increased NH3 emission (mean: 20%, 95% confidential interval: 33-67%), but reduced dissolved inorganic N leaching (-48%, -56% to -38%), N2 O emission (-44%, -48% to -39%) and NO emission (-24%, -38% to -8%). This amounted to a net reduction of 16.5% in the total N release to the environment. Inhibiting nitrification also increased plant N recovery (58%, 34-93%) and productivity of grain (9%, 6-13%), straw (15%, 12-18%), vegetable (5%, 0-10%) and pasture hay (14%, 8-20%). The cost and benefit analysis showed that the economic benefit of reducing N's environmental impacts offsets the cost of NI application. Applying NI along with N fertilizer could bring additional revenues of $163 ha(-1) yr(-1) for a maize farm, equivalent to 8.95% increase in revenues. Our findings showed that NIs could create a win-win scenario that reduces the negative impact of N leaching and greenhouse gas production, while increases the agricultural output. However, NI's potential negative impacts, such as increase in NH3 emission and the risk of NI contamination, should be fully considered before large-scale application.

Microbial N Transformations and N 2 O Emission after Simulated Grassland Cultivation: Effects of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate (DMPP)

“…In accordance with this, in an incubation experiment with layered plant residues similar to the present study, Li et al (58) found evidence for NO 3 Ϫ limitation of denitrification during the first week of residue decomposition, which was later alleviated by nitrification of N released from residues. This inhibition of N 2 O emissions by DMPP is comparable to effects observed when nitrification inhibitors are used together with inorganic fertilizers or manure (59,60). However, the effect of DMPP in the RO treatment was smaller and not significant; presumably, the shallow and uniform distribution of plant residues shifted decomposition toward more aerobic processes, while the supply of NO 3 Ϫ from soil and nitrification was sufficient to support the residual denitrification (19).…”

N2O emissions from grain cropping systems: a meta-analysis of the impacts of fertilizer-based and ecologically-based nutrient management strategies

“…Mean values and 95% confidence intervals of the backtransformed response ratios are shown. The result for nitrification inhibitors was from Qiao et al (2015) and was shown for comparison fertilizer to treatments receiving N fertilizer plus cover crop biomass. As a result, the cover crop treatments received an average of 89 kg N ha -1 more N compared to the controls with total C and N additions varying greatly, depending on cover crop biomass and species.…”

Effect of urease and nitrification inhibitors on ammonia volatilization and abundance of N‐cycling genes in an agricultural soil

“…Nitrification inhibitors block the activity of the enzyme ammonia monooxygenase, encoded by the ammonia monooxygenase gene ( amoA ) ( Weiske et al., ; Zerulla et al., ), which is responsible for the first step of nitrification, thus extending the presence of exchangeable ammonium in soils and reducing the production of N 2 O. However, prolonged retention of in soil may increase ammonia emissions ( Soares et al., ; Qiao et al., ). Dicyandiamide (DCD) and 3,4‐dimethylpyrazole phosphate (DMPP) are the most used commercial nitrification inhibitors, and they can effectively reduce nitrification rates under different laboratory and field conditions ( Yu et al., ; Gilsanz et al., ; Lan et al., ).…”