Comparison of Karanjin with other nitrification inhibitors for retardation of nitrification of urea N in soil

Summary Comparative evaluation of Kranjin and three patented nitrification inhibitors for retardation of nitrification of urea in a sandy clay loam showed that the effectiveness of the compounds tested decreased in the order: Nitrapyrin>Karanjin>A.M.>dicyandiamide.     

Radiation chemistry of an aqueous solution of glycine: compounds of interest to chemical evolution studies

Summary We have examined the radiolysis of an O₂-free aqueous solution of glycine at absorbed doses of⁶⁰Co gamma-radiation of up to 20 Mrad. At least 20 compounds are formed during radiolysis, among them several amino acids, an oligoamine, and the nitrogen-free polymers (M_w28,000 daltons). When dicyandiamide is present in the solution of glycine, various nitrogen-containing products, including some polymers (M_w12,000 daltons), are synthesized along with radiolytic products of glycine; polyglycines are not formed. We have determined the radiation-chemical yields of radiolytic-product formation and of decomposition of glycine, and have considered possible free-radical reactions leading to the radiation-induced changes observed.     

氢醌和双氰胺对种稻土壤N2O和CH4排放的影响

通过盆栽试验,研究了脲酶抑制剂氢醌（ＨＱ）、硝化抑制剂双氰胺（ＤＣＤ）及二者的组合（ＨＱ＋ＤＣＤ）对种稻土壤Ｎ２Ｏ和ＣＨ４排放的影响．结果表明,在未施麦秸粉时,所有施抑制剂的处理均较单施尿素的能显著减少水稻生长期供试土壤Ｎ２Ｏ和ＣＨ４的排放．特别是ＨＱ＋ＤＣＤ处理,其Ｎ２Ｏ和ＣＨ４排放总量分别约为对照的１／３和１／２．而在施麦秸粉后,该处理的Ｎ２Ｏ排放总量为对照的１／２,但ＣＨ４排放总量却较少差别．不论是Ｎ２Ｏ还是ＣＨ４的排放总量,施麦秸粉的都比未施的高出１倍和更多．因此,单从土壤源温室气体排放的角度看,将未腐熟的有机物料与尿素共施,并不是一种适宜的施肥制度．供试土壤的Ｎ２Ｏ排放通量,与水稻植株的ＮＯ－３Ｎ含量和土表水层中的矿质Ｎ量分别呈显著的指数正相关和线性正相关;ＣＨ４的排放通量则与水稻植株的生长量和土表水层中的矿质Ｎ量呈显著的线性负相关．在Ｎ２Ｏ与ＣＨ４的排放间,未施麦秸粉时存在着定量的相互消长关系;施麦秸粉后,虽同样存在所述关系,但难以定量化．     

Influence of slurry applications on the EUF-N fractions in the soil

Summary Increasing quantities of slurry (30, 60 and 90 m³/ha as well as 60 m³/ha + DIDIN) were applied to two sandy soils both in September and in December 1982. During the 1982/83 winter EUF-N was determined in soil horizons (0–30 cm, 30–60 and 60–90 cm).EUF-NO₃ and EUF-N_org clearly reflected the different quantities of slurry applied. The retarding effect of DIDIN on nitrification could also be demonstrated by means of the EUF-N contents.Due to the mild and humid climate prevailing in the winter of 1982/83 slurry-NO₃ of the September applications had obviously been leached out of the 0–60 cm soil layer in all treatments by February and even out of the 60–90 cm layer by March 24. Translocation of NO₃ was also observed for slurry applied in December. But in this case on March 24 the EUF-NO₃ contents in the 60–90 cm layer still reflected the quantities of slurry applied four months earlier.After slurry application the EUF-N_org fraction of a soil initially consists mainly of NH ₄ ⁺ which is rapidly oxidized to NO₃ and transferred in this form to deeper layers. As a consequence a rapid decline in EUF-N_org fraction is observed. It could therefore be expedient to consider the N_org and EUF-NH ₄ ⁺ fractions separately when slurry applications are concerned.     

Global analysis of nitrification inhibitors on grasslands nitrous oxide emission rates

Field studies have tested the effectiveness of nitrification inhibitors in reducing grassland soil nitrous oxide (N₂O) emissions. However, the magnitude of the effects on N₂O emission rates across global grasslands remains unclear owing to its spatial heterogeneity. In this study, we synthesized 40 datasets from 23 published studies. The meta-analysis revealed that effect size of nitrification inhibitors was −0.59 ± 0.07 (95% confidence interval: −0.73 to −0.46). The mitigation effect on global grassland N₂O emission rates was approximately 44.56%. Meanwhile, dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) decreased grassland N₂O emission rates by 48.31% and 32.97%, respectively (P < 0.05). The mixed effects models indicated that total nitrogen, soil bulk and air temperature were the main controlling factors, which explained 42.79%, 40.70%, and 18.59% of the variation in effect size, respectively. Considering global warming, there is considerable potential benefit from mitigating grassland N₂O emissions through the application of DCD and DMPP.     

长效碳酸氢铵缓效机理与环境效应研究

依据长效碳铵的光谱特征、理化特性及其对影响氨挥发的主要因子的分析 ,建立了土壤中氨挥发的数学模式 ,提出了长效碳铵中DCD与从碳铵中离解出来的游离态氨形成分子间氢键的新观点 ,这种弱相互作用力降低了土壤中氨的表观浓度 ,使土壤 pH在氨挥发期间降低了 0 .2～ 0 .4,延缓了NO-3 N形成时间 ,缓解了N损失 .长效碳铵能够调节N素供应的形态、时间与数量 ,减少施用化肥后引起的地面水和地下水硝酸盐的污染 .     

Nitrification and ammonia volatilisation losses from urea and dicyandiamide-treated urea in a sandy loam soil

Summary Nitrification and ammonia volatilisation losses from urea and dicyandiamide (DCD)-treated urea were studied in a sandy loam soil. Laboratory experiments indicated that 20 ppm (of soil) DCD effectively inhibited nitrification of urea over sixty days. If the urea was treated with DCD (20 ppm), ammonia emission from the soil was extended over 105 days; with urea alone, it was negligible after 15 days. A field study indicated that DCD treatment increased volatilisation losses of ammonia tremondously if urea was applied to the soil surface; these losses were minimised if the urea was placed at 5 cm depth. It would seem that nitrification inhibitors must be combined with a placement technique.     

脲酶抑制剂和硝化抑制剂的协同作用对尿素氮转化和N2O排放的影响

根据培养试验,论述了脲酶抑制剂氢醌和硝化抑制剂双氰胺和碳化钙的不同组合在土壤正常水分和渍水的条件下对于土中尿素的水解及其释出的氨的吸附、氧化和挥发以及Ｎ２Ｏ生成的影响．文章指出,配合使用氢醌和双氰胺既能延缓土中尿素的水解并使水解后释出的氨在土中得以更多和更长时间的保持,还能减少土中硝酸盐的累积、氨挥发的损失及Ｎ２Ｏ的生成．这表明在脲酶抑制剂和硝化抑制剂间可能存在一定的协同作用．很好利用这一作用,将有益于提高尿素肥效和减少其Ｎ损失与环境污染．     

双氰胺对碳酸氢铵在土壤中氮素转化的影响

采用室内培养试验方法,研究了双氰胺对碳酸氢铵中的铵态氮在土壤中动态变化的影响。结果表明,无论是碳铵与双氰胺的机械混施,还是含双氰胺的长效碳铵,在抑制铵态氮硝化产生硝态氮的同时对氨挥发也有一定的抑制作用,使土壤在更长的时间内保持更高的铵态氮含量,并对碳铵施入后土壤的酸碱化强度起到了缓冲作用。添加双氰胺不但提高了碳铵的氮肥利用率,还减少了肥料氮素损失.