中亚热带水热条件对农田置换土壤硝化强度的影响

水热条件是影响土壤硝化过程的主要环境因素.选择我国东部地区3种主要农田土壤(黑土、潮土、红壤),在江西鹰潭设置野外土壤置换试验,模拟研究中亚热带水热条件对不同土壤硝化强度的影响.2006年的试验结果表明:玉米生育期中,水热条件的变化影响土壤硝化强度的变化,从玉米种植前(2006年4月17日)到生长旺盛期(2006年7月10日),月平均气温由19.4℃上升到30.2℃,月降水量由335.6mm减少到59.2mm,3种土壤硝化强度均下降,黑土、潮土和红壤分别下降63 0%～84.8%、42.9%～66.7%和43.7%～46.2%;到玉米成熟期(月平均气温29.25℃,月降水175.6mm),土壤硝化强度又有所升高.土壤类型显著影响了土壤硝化细菌数量和硝化强度,硝化细菌数和硝化强度大小顺序为:潮土>黑土>红壤.土壤pH显著影响土壤硝化强度,相关系数r=0.778(P<0.01).此外,在玉米生育期,施用N、P、K化肥后,3种土壤的硝化细菌数以及硝化强度均升高.总体上,区域水热状况、土壤性质和施肥均影响土壤硝化强度,而且土壤与气温以及施肥处理之间存在显著的交互作用.     

Effect of soil microstructure on the relationship between the intensity of nitrification and soil moisture

The relationship between the logarithm of nitrification intensity and moisture (expressed as pF) did not have an ideal linear course in structural soils in which pores of a certain size predominated. When increasing the incubation moisture it could be observed that the intensity of nitrification decreases at pF 3.5-4.4 and increases again on further increasing the incubation moisture. The detected anomaly was observed when applying moistures corresponding to peaks of derivation pF-curves. It can be assumed that the relationship between the intensity of nitrification and moisture is modified by soil microstructure; therefore, this relationship was studied in more detail in the present communication.     

The effect of low temperature on the intensity of nitrification

Исследовали процесс нитрификации в образцах почвы, взятых с половины июля до половины ноября и инкубировавшихся при температуре, во-первых, 2°C во-вторых, 20°C. Образцы брали в дубовых и буковых лесах. Было установлено, что при такой низкой температуре, как +2°C, нитрификация достигает значительных величин. Другим интересным открытием является то, что б осенние месяцы, когда нитрификация при 20°C падает до весьма низких показателей, нитрификация при 2°C сохраняет значительную интенсивность, так что ее показатели часто равняются величиным нитрификации при 20°C. Как мы убедились, это положение обусловлено не тем, что инкубация при 2°C продолжается вдвое дольше, чем инкубация при 20°C. Главной причиной скорее являются, как кажется, понижение иненсивности аммонизации вследствие недостатка веществ, которые при разложении дают аммиак.     

Effect of montmorillonite and kaolinite on nitrification in soil

A soil not naturally containing montmorillonite (M) was amended with approximately 5, 10 or 20% M or kaolinite (K), maintained in a greenhouse under periodic cultivating and alternate wetting and drying for more than two years, and then used in perfusion studies. The incorporation of M enhanced the rate of both heterotrophic degradation of glycine and subsequent autotrophic nitrification in direct relation to the amounts of M added. In soil amended with K, neither degradation nor nitrification was stimulated. The addition of M shortened the lag phase before nitrification was initiated, increased the pH of both the soil and the perfusates, and increased the rate, but not the extent, of oxidation of ammonium to nitrite and nitrate. The addition of CaCO₃ or MgCO₃, but not of CaSO₄, also enhanced the rate of nitrification. The effects observed may have resulted from the influence of M on the pH, buffering capacity, and other soil conditions necessary for maximum activity of nitrifying microorganisms.     

Effect of submergence on subsequent nitrification in a wetland cultivated rice soil

Summary Soil samples from the surface (0–0.5 cm) and subsurface (0.5–5.0 cm) in a wetland field cultivated with rice and submerged for different periods up to 6 weeks were incubated for 2 weeks in the laboratory under flooded or unflooded condition, with added NH₄ ⁺–N. The ammonium and nitrate-N of the incubated-soils indicate that in the surface soil (a) nitrification is retarded when submerged for 4 weeks or more (b) nitrification did not resume to former levels within 2 weeks after air drying for a period of 1 week. In the subsurface soil, submergence for 2 weeks caused a retardation of nitrification but longer submergence did not reduce nitrification any further.During submergence, redox potential at 2 mm remained at relatively high values but began to decline 30 days after submergence. At 5 cm, Eh indicated reduced conditions from the time of submergence.     

放牧对若尔盖高寒草甸土壤氮矿化及其温度敏感性的影响

过度放牧和气候暖干化是若尔盖高寒草甸面临的严峻生态问题,它对土壤氮矿化过程的影响将在某种程度上决定高寒草甸生态系统的氮素利用状况。基于野外放牧实验,(禁牧(CK)、轻度放牧(L)、中度放牧(M)、重度放牧(H)),通过室内培养方法(5、10、15、20、25℃),探讨了不同放牧强度对若尔盖高寒草甸土壤氮矿化及其温度敏感性的影响。实验结果表明:放牧增加了土壤硝化速率和净氮矿化速率,其整体趋势为LMHCK。培养温度较低时(5—10℃),温度升高对硝化和净氮矿化速率无显著影响,而培养温度较高时(15—25℃),温度升高显著增加了硝化和净氮矿化速率。土壤硝态氮和无机氮积累量随培养时间增长显著增加,而铵态氮无显著增长。此外,放牧显著提高了土壤氮矿化的温度敏感性,重度放牧样地的土壤具有最高的氮矿化温度敏感性(Q10=2.72)。上述结果预示着在未来温度升高情景下,重度放牧将使土壤氮矿化速率的增速更快,短期内将通过提高氮的可利用性促进植物生长,但长远而言可能加速土壤氮素流失,从而对植物生长和高寒草甸生态系统结构与功能造成负反馈效应。     

Influence of vegetable tannins on nitrification in soil

Summary A laboratory study was performed on the effects of pure preparations of vegetable tannins on the nitrification of ammonium sulphate in soil. Purified preparations of wattle and of chestnut-oak tannins used at concentrations of 0.50, 1.00, and 2.00% (w/w) showed a fairly strong inhibition on the formation of nitrate only during the first two weeks' incubation. Similar tannin preparations used at 0.125% (w/w) concentration had practically no influence on nitrification. Generally, the wattle tannin had a slightly stronger inhibitory effect than the chestnut-oak mixture.     

脲酶/硝化抑制剂在黑土和褐土中对尿素氮转化的调控效果

本试验研究脲酶/硝化抑制剂不同组合在黑土和褐土中对尿素水解和硝化作用的调控效果,旨在筛选出适合东北黑土、褐土的高效抑制剂组合.采用室内恒温、恒湿培养试验,以不施氮肥(CK)和施用普通尿素肥料(U)为对照,研究分别添加脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)及其与硝化抑制剂双氰胺(DCD)、3,4-二甲基吡唑磷酸盐(D...     

Effect of soil temperature on sorghum emergence

Soil temperature strongly influences both percentage germination and time of emergence of sorghum. Ten hybrids were hand planted in the field. Soil surface was irrigated frequently and emerging plants were counted daily. On three treatments, soil temperature was monitored every hour at five depths. Treatments were designed to achieve a range in surface soil temperature. Results of the study indicated an optimum germination temperature of about 23°C and a heat requirement of 67 degree days. The maturity classifications of the hybrids did not show a consistent trend in their heat requirement for emergence.     

Effects of temperature and prior flooding on intensity and sorption of phosphorus in soil

Summary Effects of temperature and flooded-drained soil conditions on 0.01M CaCl₂ extractable phosphorus (soluble P) were investigated in four soils over the period of 42 days after fertilizer-P application. These soils show severe induced P deficiency problem in crops following flooded rice culture. The effects of temperature on the reaction rate constants were determined and activation energy was calculated. Increasing soil temperature as well as prior flooding of soil decreased soluble P concentration but the effect of the latter was dominant. The decrease in soluble P concentration in these soils with time followed a first order kinetics and the rate constant (K₁) increased as the temperature increased from 10°C to 30°C. The activation energy (Ea) for the kinetics of soluble P concentration in soil, as affected by temperature, was found to be 8.9 and 34.5 KJ mol⁻¹ for Meyers and Willows clay, respectively, over the temperature range studied.     

Effect of simazine,lindane and ceresan on soil respiration and nitrification rates

Summary The effect of three pesticidesviz, simazine, lindane and ceresan upto 100-fold of field application was studied on organic matter mineralization as well as on nitrification rates in Delhi alluvial soil. The normal rate of simazine (2 ppm) did not influence CO₂ evolution but higher concentrations suppressed it. Lindane and ceresan inhibited CO₂ production from soil by normal concentrations but the same CO₂ production was enhanced in berseem roots treated soil upto 10 ppm of ceresan.The nitrification of ammonium sulphate in soil due to these pesticides was impaired significantly for varying periods. The inhibitory effect of higher concentrations was marked only upto 3 weeks, subsequently the rate of nitrification was restored. Among the nitrifiers, Nitrobacter were more susceptible as compared to Nitrosomonas.     

Acceleration by montmorillonite of nitrification in soil

A soil naturally containing montmorillonite (M) was amended with 10% M and sequentially perfused with glycine, with fresh glycine being added every 16–17 d after nitrification of the previously added glycine-nitrogen had reached a plateau. In some systems, the old perfusates were replaced each time with a fresh glycine solution; in others, the initial perfusate was not replaced but only adjusted each time to the original 200 ml volume and a comparable glycine concentration (140 μg NH₂-N/ml). The incorporation of M enhanced the rates of heterotrophic degradation of glycine and subsequent autotrophic nitrification, but these stimulatory effects decreased with each successive perfusion. The reasons for these decreases are not known, but they did not appear to be related to inorganic nutrition, as perfusion with a mixed cation solution after five perfusion cycles did not significantly enhance nitrification in either the check or M-amended soils during three subsequent perfusions with glycine. The enhancement of nitrification by M appeared to be a result, in part, of the greater buffering capacity of the M-amended soil, as indicated by lesser reductions in the pH of perfusates from the M-amended soil, by titration curves of the soils, and by the greater and longer stimulation of nitrification in the cheek soil amended with 1% CaCO₃, which had a greater buffering capacity than did M. The stimulation by CaCO₃ may also have been partially the result of providing CO₂ for the autotrophic nitrifyers. Significant concentrations of nitrite accumulated only in perfusates from soil amended with CaCO₃. Air-drying and remoistening the soils enhanced nitrification of subsequently added glycine, especially in the check soil. The importance of pH-mediation, of the production of inhibitors, and/or of feed-back inhibition was indicated by the lower rate and extent of nitrification in systems wherein the perfusates were not replaced between successive additions of glycine. Although the results of these studies confirmed previous observations that M enhances the rate of nitrification in soil, the mechanisms responsible for this stimulation are still not known.     

土壤硝化作用的抑制剂调控及其机理

既要保证氮肥在优质高效农业生产中的促进作用,又要保证农业和环境的可持续发展,如何提高氮肥利用率、减轻氮肥污染成了解决问题的关键.从氮素在土壤中的生物化学转化过程入手,通过抑制剂的施用来调控氮素的转化,减缓硝化过程的进行,是解决该问题的一种有效措施.本文从硝化抑制剂的定义、筛选硝化抑制剂的条件、国内外较受关注的硝化抑制剂品种以及硝化抑制机理等几个方面对目前的研究进展进行综述,并提出目前研究中存在的问题及今后的研究方向.     

Effects of sulpha drugs on nitrification of urea in soil

Summary A laboratory study was made of the influence of the sulpha drugs sulphathiazole, sulphanilamide, sulphapyridine, sulphaguanidine, sulphadiazine and sulphadiamidine on nitrification of urea applied to a sandy clay loam soil of pH 7.8. Sulphathiazole applied at 2 ppm inhibited the nitrification of urea most effectively. Sulphadiazine and sulphadiamidine were also found to have nitrification inhibitory properties and need further testing. About 14% of applied urea N accumulated as nitrites after 1 week of incubation. Application of sulpha drugs along with urea reduced nitrite accumulation. re]19760203