Effects of soil properties on urea-N transformation and efficacy of nitrification inhibitor 3, 4-dimethypyrazole phosphate (DMPP)
2022
Gao, Jichao | Luo, J. (Jiafa) | Lindsey, S. B. (Stuart B.) | Shi, Yuanliang | Wei, Zhanbo | Wang, Lingli | Zhang, Lei
Ammonia (NH₃) and nitrate (NO₃ ⁻) are two major sources of N loss during the urea-N transformation process in soil. 3, 4-dimethypyrazole phosphate (DMPP) is a nitrification inhibitor that could effectively limit the NO₃ – production process but aggravate NH₃ emissions. NH₃ volatilization, NO₃ – production and the efficiency of DMPP are all influenced by different soil factors. The objective of this study was to understand the effects of soil properties on N losses after urea application and DMPP efficacy. A laboratory incubation experiment was set up with urea applied to seven different types of soil at a rate of 0.25 g N/kg soil, with or without DMPP, (at a rate of 1% of the N applied in the fertilizer). Urea content, NH₃ losses and mineral N were measured regularly for 50 days after treatment addition. NO₃ –N production rates, inhibition efficiencies of DMPP and urea half-lives were calculated based on the measured NO₃ –N and urea concentrations. Results showed that urea half-life was negatively correlated with soil total organic carbon (TOC) (r = −0.930). NO₃ – production rate was correlated with soil pH (r = 0.670), sand (r = 0.639) and clay content (r = −0.632). The efficiency of DMPP for inhibiting NO₃ – production was positively correlated with NO₃ – production rate (r = 0.721). NH₃ volatilization was positively correlated with soil pH (r = 0.657) and sand content (r = 0.687) and negatively correlated with urea half-life (r = −0.586). Greater inhibition efficiency of DMPP led to higher NH₃ losses. Urea degradation, NH₃ loss, NO₃ – production rate and the inhibition efficiency of DMPP were significantly affected by soil properties and the risk of NH₃ volatilization was increased by DMPP application.
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