硝化/脲酶抑制剂及生物质炭对养殖肥液灌溉土壤氮素转化的影响

化学氮肥添加硝化/脲酶抑制剂和生物质炭均可起到减少硝态氮淋溶损失或气态损失的作用。为研究以有机氮素和无机氮素复合系统的养殖肥液为主体的新型肥料对减少氮素损失的作用,在控制施氮量相同的前提下,通过设置不同种类的抑制剂和抑制剂组合方式：养殖肥液单施（CK）、尿素单施（U）、养殖肥液+双氰胺（DCD）、养殖肥液+氢醌（HQ）、养殖肥液+双氰胺+氢醌（DCD+HQ）、养殖肥液+生物质炭（B）,探究硝化抑制剂、脲酶抑制剂单施或配施及生物质炭的添加对养殖肥液施用后土壤氮素转化的影响。结果表明,土壤N₂O-N累积排放量抑制率呈现DCD+HQ > HQ > DCD > B,抑制率依次为21.97%、19.39%、18.55%和10.71%;土壤氮素矿化速率依次为DCD+HQ > DCD > HQ > B > CK > U;土壤氮素硝化速率由大到小依次为CK > HQ > B > DCD+HQ > DCD > U。研究表明,DCD+HQ抑制剂组合模式更加有利于防控养殖肥液灌溉过程土壤氮素的损失。     

Precipitation but not soil texture alters effectiveness of dicyandiamide to decrease nitrate leaching from dairy cow urine

This experiment compared the effectiveness of the nitrification inhibitor dicyandiamide (DCD) in decreasing NO₃‐N leaching from dairy cow urine (1000 kg N/ha equivalent). DCD was applied to perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) on three soil types (silt loam, sandy loam and clay) and under two precipitation regimes using intact soil monolith zero tension lysimeters (50 cm diameter by 65 cm deep). Over the two experiment years, annual precipitation (rainfall plus supplemented irrigation) covered the range 1103 to 2351 mm. Soil type affected the forms of N that leached after urine application. Most urea was lost from the clay soil in the first drainage collections after application. Ammonium‐N leached from the sandy soil. Apart from one soil type (sandy loam) giving a nil response to DCD in 1 yr, there was no strong evidence that soil type changed DCD effectiveness (the amount of NO₃‐N retained, expressed as a percentage of the NO₃‐N leached from untreated urine). Where DCD decreased leaching, effectiveness ranged between 6 and 57% with a mean value of 34 ± 5%. Drainage depth explained 50% of the variation in DCD effectiveness (P < 0.05) and indicated a 7% decrease per 100 mm extra drainage. Extra pasture growth and N uptake were strongly related to the amount of N saved by DCD application. We conclude that there may be scope to use rainfall/drainage as an estimate of likely DCD effectiveness at a site, but further work is required to test this across a wider range of circumstances.     

亲水作用色谱－电喷雾串联质谱法测定生鲜牛乳及奶粉中的双氰胺

建立了检测生鲜牛乳及奶粉中双氰胺的亲水作用色谱-电喷雾串联质谱(HILIC-ESI-MS/MS)分析方法.样品经乙腈提取后经亲水作用色谱柱分离,电喷雾串联四级杆质谱检测.结果显示,双氰胺标准曲线在0.5～100μg/L浓度范围内线性良好.相关系数(r)大于0.99;在5～50μg/kg添加水平下,回收率在80.1％～88.2％之间,相对标准偏差(RSD)均小于10％(n=6);方法操作简便、灵敏度高,适用于生鲜牛乳及奶粉中双氰胺的筛查及确证分析.     

氰氨态氮的硝化抑制效应及其在农田的应用

本文探讨了氰氨态氮的硝化抑制效应,比较了氰胺和双氰胺在农田的使用效果。研究结果表明,氰胺和双氰胺都能抑制硝化作用,从而提高氮肥利用率。在水田土壤中,氰胺的分解速度比双氰胺缓慢,硝化抑制效应持续时间较长,其增效作用比双氰胺大;在旱田土壤则相反,双氰胺的硝化抑制效应大于氰胺。在正常的条件下,氰胺是氰氨化钙分解的主要产物。试验结果表明,氮肥与氰氨态氮的配合比例以5:1～3:1为宜。在多数情况下,这个浓度水平对作物无害,并能充分发挥增效作用。同时,在水田土壤中,氮肥与氰氯化钙配施,其增效作用比双氰胺大,而成本却比双氰胺为低。     

Nitrification and denitrification in an acidic soil of tea (Camellia sinensis L.) field estimated by δ15N values of leached nitrogen from the soil columns treated with ammonium nitrate in the presence or absence of a nitrification inhibitor and with slow-release fertilizers

Forty-two-day-old wheat (Triticum aestivum L. var. Asakazekomugi) plants were treated with complete, K-free (—K), Ca-limited (—Ca), and Mg-free (—Mg) nutrient solutions for 10 days using 2 mM NH₄NO₃ as the nitrogen source, which was replaced with 4 mM ¹⁵ NH₄C1 or Na¹⁵NO₃ for the subsequent 2 days to investigate the absorption, translocation, and assimilation of inorganic nitrogen in relation to the mineral supply. In another experiment plants were grown on NO₃ ^?, NH₄ ⁺, NH₄N0₃, and K-free and Ca-limited NH₄N0₃ nutrient solutions for 10 days, and then in the latter three treatments the nitrogen source was replaced with NO₃ ^? and half of the —K plants received K for 6 days to examine the changes in the nitrate reductase activity (NRA).

Wheat plants absorbed NH₄ ^?N and NO₃-N at a similar rate. Influence of K on the absorption of N0₃-N was stronger than that on the absorption of NH₄-N in wheat plants. The supply of K to the —K plants increased the absorption of NO₃-N, while the absorption of NH₄-N still remained at a lower rate in spite of the addition of K. A limited supply of Ca and lack of Mg in nutrient media slightly affected the absorption of NH₄-N. The influence of K was stronger on the translocation of nitrogen from roots to shoots, while Ca and Mg had little effect. When K was supplied again to the —K plants the translocation of NO₃,-N was more accelerated than that of NH₄-N. Incorporation of NH₄-N into protein was higher than that of NO₃-N in all the tissues; root, stem, and leaf. Assimilation of NH₄-N and NO₃-N decreased by the —K and —Mg treatments.

Leaf NRA of wheat plants decreased in the —K and —Ca plants. Higher leaf NRA was found when K was given again to the —K plants than when the plants were continuously grown in K-free media. Replacement of NO₃ ^? with NH₄ ⁺ as the nitrogen source caused a decline of leaf NRA, while the supply of both NH₄ ^?N and NO₃-N slightly affected the leaf NRA.     

双氰胺对马铃薯农田土壤铵态氮、硝态氮转化的影响

通过田间试验,研究双氰胺(DCD)对块茎类蔬菜马铃薯各个生长时期农田土壤铵态氮、硝态氮转化的影响。结果表明：加入双氰胺后,土壤中铵态氮含量均显著提高（p＜0.05）,硝态氮含量显著降低（p＜0.05）。     

稻草还田下添加DCD对稻田CH4、N2O和CO2排放的影响

为研究秸秆还田下硝化抑制剂的效应,本研究借助温室盆栽,设置5个处理:不施肥(CK)、传统施肥(CF)、传统施肥配施硝化抑制剂双氰胺DCD(CF+DCD)、传统施肥稻草还田(CF+S)、传统施肥稻草还田配施DCD(CF+S+DCD),探讨秸秆还田下施用DCD对水稻整个生育期土壤CH_4、N_2O和CO_2排放的影响。结果表明:整个生育期,CH_4和CO_2排放量以CF+S最高,CF+S+DCD次之,而CK最低;N_2O排放量以CF最高,CF+DCD次之,而CF+S+DCD最低。与CF和CF+S相比,施用硝化抑制剂后CH_4和N_2O减排效果显著,而CO_2减排不显著。就水稻产量、综合温室效应(GWP)、温室气体强度(GHGI)和净生态系统经济预算(NEEB)而言,秸秆还田和硝化抑制剂施用,都可显著提高水稻产量和NEEB,而降低GWP和GHGI;与CF和CF+S相比,施用硝化抑制剂后,CF+DCD和CF+S+DCD分别增产9.5%和10.0%,NEEB增加16.8%和20.1%;GWP分别降低23.7%和21.0%,GHGI降低23.7%和21.1%。可见,无论稻草还田与否,硝化抑制剂对温室气体排放及水稻产量的影响效应比较稳定。因此,稻草还田配施DCD(即CF+S+DCD处理)在保证水稻产量的基础上,显著降低稻田土壤CH_4和N_2O排放,是一种经济可行的温室气体减排措施。     

The use of a nitrification inhibitor, dicyandiamide (DCD), to decrease nitrate leaching and nitrous oxide emissions in a simulated grazed and irrigated grassland

Abstract. In grazed dairy pasture systems, a major source of NO₃^– leached and N₂O emitted is the N returned in the urine from the grazing animal. The objective of this study was to use lysimeters to measure directly the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in decreasing NO₃^– leaching and N₂O emissions from urine patches in a grazed dairy pasture under irrigation. The soil was a free‐draining Lismore stony silt loam (Udic Haplustept loamy skeletal) and the pasture was a mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). The use of DCD decreased NO₃^–‐N leaching by 76% for the urine N applied in the autumn, and by 42% for urine N applied in the spring, giving an annual average reduction of 59%. This would reduce the NO₃^–‐N leaching loss in a grazed paddock from 118 to 46 kg N ha^–1 yr^–1. The NO₃^–‐N concentration in the drainage water would be reduced accordingly from 19.7 to 7.7 mg N L^–1, with the latter being below the drinking water guideline of 11.3 mg N L^–1. Total N₂O emissions following two urine applications were reduced from 46 kg N₂O‐N ha^–1 without DCD to 8.5 kg N₂O‐N with DCD, representing an 82% reduction. In addition to the environmental benefits, the use of DCD also increased herbage production by more than 30%, from 11 to 15 t ha^–1 yr^–1. The use of DCD therefore has the potential to make dairy farming more environmentally sustainable by reducing NO₃^– leaching and N₂O emissions.     

土壤中双氰胺残留量的检测方法

为检测双氰胺的残留量,在土壤样品加入自制的双氰胺-15N4内标,经超声萃取及冷冻离心处理,采用电喷雾(ESI+)正离子扫描模式,在选择离子监控模式(SRM)下,建立高效液相色谱-串联质谱法定量分析双氰胺的方法。结果表明,该方法在10~50μg·L-1的浓度范围内线性良好,标准曲线回归方程为y=0.9698 x+0.0039,r2=0.9994。方法的检出限与定量限分别为5μg·L-1和16μg·L-1,回收率为97%~104%,RSD1.2%(n=6)。采用该方法检测3类不同的土壤样品,其结果均与理论预期相符。综上,该方法简便、灵敏、准确,为科学施用含双氰胺氮肥的研究提供了一种表征手段。