Effects of Nitrification Inhibitors on Soil Nitrification and Ammonia Volatilization in Three Soils with Different pH

Lei Cui,Lili Zhang,Furong Xiao,Dongpo Li,Yuchao Song,Yongkun Cui,Yan Xue,Ye Zheng,Zhijie Wu,Jinming Zhang,Yonghua Li

doi:10.3390/agronomy11081674

Abstract

The application of nitrification inhibitors (NIs) is considered to be an efficient way to delay nitrification, but the effect of NIs combinations on soil nitrification and ammonia (NH3) volatilization are not clear in soils with different pH values. In this study, we explored the effect of nitrapyrin (CP) and its combinations with 3, 4-dimethylepyrazole phosphate (DMPP), dicyandiamide (DCD) on the transformation of nitrogen, potential nitrification rate (PNR), and ammonia (NH3) volatilization in a 120-day incubation experiment with three different pH values of black soil. Treatments included no fertilizer (Control), ammonium sulfate (AS), AS+CP (CP), AS+CP+DMPP (CP+DMPP), and AS+CP+DCD (CP+DCD). The application of NIs significantly decreased NO3−-N contents and potential nitrification rate (p < 0.05), while significantly increased NH4+-N contents (p < 0.05), especially CP+DCD and CP+DMPP were the most effective in the neutral and alkaline soils, respectively. In the acid soil, CP significantly increased total NH3 volatilization by 31%, while CP+DCD significantly reduced by 28% compared with AS. However, no significant difference was found in NH3 volatilization with and without NIs treatments (p > 0.05) in the neutral and alkaline soils. In conclusion, the combined nitrification inhibitors had the better efficiency in all three tested soils. CP+DCD and CP+DMPP are the most effective in inhibiting soil nitrification in the clay soils with higher pH value and lower organic matter, while CP+DCD had the potential in mitigating environment pollution by reducing N loss of NH3 volatilization in the loam soil with lower pH value and higher organic matter. It provided a theoretical basis for the application of high efficiency fertilizer in different soils. Further studies under field conditions are required to assess the effects of these nitrification inhibitors.

Highlights

Nitrate nitrogen (NO3−-N) is a negative ion and weakly adsorbed to the soil, and it tends to leaching [1]
All of the treatments with nitrification inhibitors (NIs) significantly decreased potential nitrification rate (PNR) in the three soils, especially in both neutral and alkaline soils (Figure 3), suggesting that NIs were more effective in inhibiting nitrification in these two soils [33]
No significant difference in inhibiting nitrification was detected in the acid soil among all of the NIs treatments

Summary

Introduction

Nitrate nitrogen (NO3−-N) is a negative ion and weakly adsorbed to the soil, and it tends to leaching [1]. The application of nitrification inhibitors (NIs) with ammonium-based fertilizer is considered to be the most efficient way to reduce NO3−-N contents and mitigate environmental pollution through delaying nitrification. Nitrification inhibitors (NIs) delay the transformation of ammonium N (NH4+-N) to nitrate N (NO3−-N) and decrease N loss through inactivating the ammonia monooxygenase (AMO) enzyme, which is the key enzyme that results in the first, rate-limiting, step of nitrification [4]. DCD has been proven to be effective in reducing nitrification rates and nitrate leaching, is non-volatile and low cost, but one of the major limitations of DCD is that it leaches out of the rooting zone, lowering its effectiveness, and the application rate is high [8,9]. The application of combined NIs will be cost-effective, which is more efficient in inhibiting nitrification

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