Purpose

Nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) has been widely proposed to reduce nitrogen (N) loss and improve N availability in paddy soil. However, little knowledge exists regarding the optimum dose of DMPP required for inhibiting nitrification in different soil types.

Materials and methods

In undisturbed soil columns under greenhouse conditions, dynamics of ammonium (NH₄⁺–N) and nitrate (NO₃⁻–N) in floodwater and leachate, and ammonia (NH₃) volatilization were studied in two paddy soils (hydragic and gleyed), amended with urea-N at 180 N kg/ha with DMPP applied at 0, 0.45, 0.675, and 0.90 kg/ha (0.25%, 0.375%, and 0.5% of urea-N, respectively). The source of DMPP was Entec® 46 (46% urea-N and DMPP at 0.5% of urea-N) that was mixed with pure urea (fertilizer mixture).

Results and discussion

DMPP application rates and soil types significantly influenced NH₄⁺–N and NO₃⁻–N concentrations in floodwater and leachate; however, DMPP application rates did not significantly impact NH₄⁺–N concentrations in floodwater. Results indicate that concentrations of both NH₄⁺– N and NO₃⁻–N in leachate and floodwater were peaked between 10 and 20 days after fertilizer application. Increased DMPP application rates increased floodwater and leachate NH₄⁺–N concentrations, while significantly decreasing NO₃⁻–N concentrations in floodwater and leachate, with largest decrease seen in the 0.90-kg/ha DMPP treatment. NH₃ emissions were observed after fertilizer was applied and decreased gradually, with no significant differences in response to the DMPP amount. The total N losses via leaching and NH₃ emission were significantly decreased at treatments of 0.675 kg/ha and 0.90 kg/ha DMPP, and positively correlated with sand fraction in soil. Compared with the gleyed paddy soil, higher total N loss was observed in the hydragic paddy soil, which was related to the higher sand fraction of the hydragic paddy soil and the better behavior of DMPP in this soil type.

Conclusions

Considering economic factors, mineral N concentrations in floodwater and leachate, together with N losses via leaching and volatilization, application of 0.675 kg/ha DMPP could significantly inhibit nitrification in the hydragic paddy soil while application of 0.90 kg/ha DMPP was shown to be the best choice to inhibit nitrification in the gleyed paddy soil.

中文翻译：

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不同剂量的3,4-二甲基吡唑磷酸酯对两种水稻土矿质氮流失的影响

目的

硝化抑制剂3,4-二甲基吡唑磷酸酯（DMPP）已被广泛提出来减少稻田土壤中的氮（N）损失并提高氮的利用率。但是，关于抑制不同土壤类型中硝化作用所需的最佳DMPP剂量知之甚少。

材料和方法

在温室条件下未受干扰的土壤柱中，研究了两种稻田（湿润和变灰）中铵态氮（NH ₄ ⁺ -N）和硝酸盐（NO ₃ ^-- N）在洪水和渗滤液中的动态以及氨（NH ₃）的挥发。 ，以180 N kg / ha的尿素-N进行了修正，并以0、0.45、0.675和0.90 kg / ha的DMPP用量（分别为0.25％，0.375％和0.5％的尿素-N）施用。DMPP的来源是46（46％的尿素-N和DMPP的0.5％的尿素-N）与纯尿素（肥料混合物）混合。

结果和讨论

DMPP的施用量和土壤类型显着影响了洪水和渗滤液中NH ₄ ⁺ -N和NO ₃ ^-- N的浓度。但是，DMPP的施用率并未显着影响洪水中的NH ₄ ⁺ -N浓度。结果表明，在施肥后的10到20天之间，渗滤液和洪水中NH ₄ ⁺ -N和NO ₃ ^-- N的浓度均达到峰值。增加DMPP施用率增加洪水和渗滤液NH ₄ ⁺ -N浓度，而降低显著NO ₃ ^-洪水和渗滤液中的-N浓度，在0.90-kg / ha DMPP处理中下降最大。施肥后观察到NH ₃排放并逐渐减少，对DMPP量的响应无明显差异。在DMPP为0.675 kg / ha和0.90 kg / ha的条件下，浸出和NH ₃排放造成的总氮损失显着降低，并且与土壤中的沙含量呈正相关。与水ley稻相比，在水合稻田中观测到较高的总氮损失，这与水合稻田中较高的沙含量和DMPP在该类型土壤中的良好行为有关。

结论

考虑到经济因素，洪水和沥滤液中的矿物质氮含量，以及由于淋溶和挥发造成的氮损失，施用0.675 kg / ha DMPP可以显着抑制水合水稻土的硝化作用，而施用0.90 kg / ha DMPP则是最有效的方法。抑制稻田土壤硝化的最佳选择。