ABSTRACT

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.

摘要

氨（NH ₃）和硝酸盐（NO ₃ ^-）是土壤中尿素-N转化过程中N损失的两个主要来源。3, 4-二甲基吡唑磷酸盐（DMPP）是一种硝化抑制剂，可有效限制NO ₃ ^–生产过程，但会加重NH ₃排放。NH ₃挥发，NO ₃ ^–DMPP的产量和效率都受不同土壤因素的影响。本研究的目的是了解土壤性质对尿素施用后氮损失和 DMPP 功效的影响。建立了实验室孵化实验，将尿素以 0.25 克 N/kg 土壤的比例施用于七种不同类型的土壤，有或没有 DMPP（以肥料中施氮的 1% 的比例）。尿素含量、NH ₃损失和矿物质N在添加处理后的50天内定期测量。NO ₃ ^– N 生成率、DMPP 的抑制效率和尿素半衰期是根据测量的 NO ₃ ^–计算得出的N 和尿素浓度。结果表明，尿素半衰期与土壤总有机碳（TOC）呈负相关（r = -0.930）。NO ₃ ^–生产速率与土壤 pH ( r = 0.670 )、沙子 ( r = 0.639 ) 和粘土含量 ( r = -0.632) 相关。DMPP抑制NO ₃ ^–产生的效率与NO ₃ ^–产生率呈正相关（r = 0.721）。NH ₃挥发与土壤pH值（r=0.657）和含沙量（r =0.687）呈正相关，与尿素半衰期呈负相关（r = -0.586）。DMPP 更高的抑制效率导致更高的NH ₃损失。尿素降解、NH ₃损失、NO ₃ ^-产率和DMPP 的抑制效率受土壤性质的显着影响，且施用DMPP 增加了NH ₃挥发的风险。