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1.
《Communications in Soil Science and Plant Analysis》2012,43(18-20):3045-3057
Abstract Chemical transformations of ammonium nitrate (NH4NO3) and urea‐nitrogen (N), at different rates of application, were studied in a Candler (Typic Quartzipsamment) and Wabasso (sandy, Alfic Haplaquod) sand by incubating fertilized surface soil (from 0 to 15 cm depth) samples at 10% moisture content (by weight) in the laboratory at 25±1°C. During the 7 d incubation, the percentage of transformation of NH4‐N into NO3‐N was 33 to 41 and 37 to 41% in the Candler fine sand and Wabasso sand, respectively, at application rates of 1.00 g N kg1. In a parallel experiment, 85 to 96% of urea applied (equivalent to 0.25 to 1.00 g N kg‐1soil) was hydrolyzed to NH4‐N within 4 d in the Candler soil, whereas it required 7 d to hydrolyze 90 to 95% of the urea applied in the Wabasso soil. No nitrification was evident for 30 days in the Candler fine sand which received urea application equivalent to ≥ 0.50 g N kg‐1. In the urea‐amended Wabasso sand, the formation of NO3 decreased as the rate of urea‐N increased. Possible loss of N from NH3 volatilization or inhibition of activity of nitrifiers due to elevated soil pH (8.7 to 9.2) during the incubation of urea amended soils may have caused very low nitrification. 相似文献
2.
Comparison of the effects of potassium azide (KN3) and 2-chloro-6-(trichloromethyl)-pyridine (N-Serve) on transformations of urea N in soils showed that, unlike N-Serve, KN3 retards urea hydrolysis in soils, but does not prevent NO?2 accumulation or appreciably retard nitrification of urea-N in soils that accumulate substantial amounts of NO?2 when treated with urea. It is deduced that KN3 added with urea to soils that accumulate NO?2 on treatment with urea is decomposed by reaction with NO?2.The work reported, together with previous work, indicates that KN3 has limited value compared with N-Serve as an inhibitor of nitrification in soils and that its effectiveness as a nitrification inhibitor depends to a large extent on the soil and the form of nitrifiable N applied. 相似文献
3.
The effects of 15N-labelled urea, (NH4)2SO4 and KNO3 on immobilization, mineralization, nitrification and ammonium fixation were examined under aerobic conditions in an acid tropical soil (pH 4.0) and in a neutral temperate soil (pH 6.8). Urea, (NH4)2SO4 and KNO3 slightly increased net mineralization of soil organic nitrogen in both soils. There was also an apparent Added Nitrogen Interaction (ANI) i.e. added labelled NH4-N stood proxy for unlabelled NH4-N that would otherwise have been immobilized. So far as immobilization and nitrification were concerned, urea and (NH4)2SO4 behaved very similarly in each soil. Immobilization of NO3-N was negligible in both soils. Some of the added labelled NH4-N was rapidly fixed, more by the temperate soil than by the tropical soil. This labelled fixed NH4-N decreased during incubation, in contrast to labelled organic N, which did not decline. 相似文献
4.
N2O, NH3 and NOx Emissions as a Function of Urea Granule Size and Soil Type Under Aerobic Conditions
We examined the influence of various urea granule sizes (< 2, 7.0, 9.9 and 12.7 mm) applied into a silt loam soil (experiment 1) and soil types (sandy, silt and clay loam) treated with the largest granule (experiment 2) on gaseous N loss (except N2) at field capacity. The prilled urea (PU) was mixed into the soil whereas the urea granules were point-placed at a 5.0-cm depth. For experiment 1, N2O emission was enhanced with increasing granule size, ranging from 0.17–0.50% of the added N during the 45-day incubation period. In the case of experiment 2, the sandy loam soil (0.59%) behaved similarly with the silt loam (0.53%) but both showed remarkably lower emissions than were found for the clay loam soil (2.61%). Both nitrification and N2O emissions were delayed by several days with increasing granule size, and the latter was influenced by mineral N, soil water and pH. By contrast, the NH3 volatilization decreased with increasing granule size, implying the inhibition of urease activity by urea concentration gradients. Considering both experimental results, the NH3 loss was highest for the PU-treated (1.73%) and the larger granules regardless of soil type did not emit more than 0.27% of the added N over 22 days, possibly because the high concentrations of either mineral N or NH4 + in the soil surface layer (0–2.5 cm) and the high H+ buffering capacity might regulate the NH3 emission. Similar to the pattern of NH3 loss, NOx emission was noticeably higher for the PU-treated soil (0.97%) than for the larger granule sizes (0.09–0.29%), which were the highest for the sandy and clay loam soils. Positional differences in the concentration of mineral N and nitrification also influenced the NOx emission. As such, total NH3 loss was proportional to total NOx emission, indicating similar influence of soil and environmental conditions on both. Pooled total N2O, NH3 and NOx emission data suggest that the PU-treated soil could induce greater gaseous N loss over larger urea granules, largely in the form of NH3 and NOx emissions, whereas a similar increase with the largest granule size was mainly due to the total N2O flux. 相似文献
5.
A study was made of the influence of substrate on the root releases of hydrogen ions (H+) and bicarbonate ions (HCO3 ‐) by corn (Zea mays, cv.Dea) grown between the 5/6 leaf and the 9/10 leaf stage in two different growth media, siliceous or calcareous sand. Different nutrient solutions were supplied in separate experiments, but in all cases, nitrogen was in the form of nitrate (NOg"), and iron chelates were present in solution. In siliceous sand the pH generally increased, but acidification appeared with low NO3 ‐ nutrition. Roots released H+ and HCO3 ‐ simultaneously, and these ions partially reacted to form H2CO3. The pH variations depended on the balance of the released ions and on the low buffer capacity in this slightly acidic pH range. The algebraic sum of the ion effluxes was approximately equal to the sum of the ion uptakes; no stoichiometric coupling between the total H+ effluxes and the NO3 ‐ or potassium (K+) uptakes was recorded. In calcareous sand HCO3 ‐ was released by the roots, but the H+ seedling effluxes always acidified the solutions with regard to the reference solutions in calcareous sand without plants. Even though HCO3 ‐ was released in great quantities by plants, the pH of the solutions did not become alkaline because of the high buffer capacity of the solution in contact with the calcareous medium. In this environment the plants reacted to the high levels of HCO3 ‐ and showed symptoms of lime‐induced chlorosis. To overcome the poor physicochemical conditions, H+ was released from the corn roots, and this H+ efflux was correlated to the total alkalinity of the solution. 相似文献
6.
The N2O product ratio of nitrification and its dependence on long-term changes in soil pH 总被引：1，自引：0，他引：1
The contribution of nitrification to the emission of nitrous oxide (N2O) from soils may be large, but its regulation is not well understood. The soil pH appears to play a central role for controlling N2O emissions from soil, partly by affecting the N2O product ratios of both denitrification (N2O/(N2+N2O)) and nitrification (N2O/(NO2−+NO3−). Mechanisms responsible for apparently high N2O product ratios of nitrification in acid soils are uncertain. We have investigated the pH regulation of the N2O product ratio of nitrification in a series of experiments with slurries of soils from long-term liming experiments, spanning a pH range from 4.1 to 7.8. 15N labelled nitrate (NO3−) was added to assess nitrification rates by pool dilution and to distinguish between N2O from NO3− reduction and NH3 oxidation. Sterilized soil slurries were used to determine the rates of chemodenitrification (i.e. the production of nitric oxide (NO) and N2O from the chemical decomposition of nitrite (NO2−)) as a function of NO2− concentrations. Additions of NO2− to aerobic soil slurries (with 15N labelled NO3− added) were used to assess its potential for inducing denitrification at aerobic conditions. For soils with pH?5, we found that the N2O product ratios for nitrification were low (0.2-0.9‰) and comparable to values found in pure cultures of ammonia-oxidizing bacteria. In mineral soils we found only a minor increase in the N2O product ratio with increasing soil pH, but the effect was so weak that it justifies a constant N2O product ratio of nitrification for N2O emission models. For the soils with pH 4.1 and 4.2, the apparent N2O product ratio of nitrification was 2 orders of magnitude higher than above pH 5 (76‰ and 14‰). This could partly be accounted for by the rates of chemodenitrification of NO2−. We further found convincing evidence for NO2−-induction of aerobic denitrification in acid soils. The study underlines the role of NO2−, both for regulating denitrification and for the apparent nitrifier-derived N2O emission. 相似文献
7.
G. Nakos 《Soil biology & biochemistry》1976,8(5):379-383
In incubation experiments in the laboratory interactions of urea or NH4NO3 with humus from stands of fir (Abies cephalonica, Loudon) growing on soils developed from flysch (shales) and limestone and with humus from stands of black pine (pinus nigra, Arn.) growing on soils developed from peridotites, limestone and schists were investigated.Fir humus from stands on flysch and limestone and black pine humus from limestone showed nitrification but it was absent from black pine humus from stands on peridotites and on schists. Humus from stands on schists showed appreciable ammonification. Increasing concentrations of urea did not initiate nitrification in the latter type of humus. No substantial N immobilization was detected in spite of relatively high P immobilization. Increases in concentration of Ca, Mg and K occurring on incubation of humus samples were related to the ability of a humus type to nitrify rather than to concentrations of added urea-N.Urea was hydrolyzed rapidly to NH+4 during contact with various types of humus, resulting in an increase of pH. Production of NH+4 from urea was only minimally affected by drying the humus samples at 70°C for 20 h before incubation but was reduced to 30% at 1–5°C. 相似文献
8.
生物质炭施用可能对土壤中氮素硝化过程和N2O排放产生影响。本研究通过室内培养试验，研究铵态氮肥与玉米秸秆生物质炭施用量（0、1%、2%、5%、10%w/w）对酸性（pH=5.10）和石灰性紫色土（pH=8.15）氮素硝化率、净硝化速率及N2O排放特征的影响。结果表明：（1）酸性和石灰性紫色土生物质炭处理平均净硝化速率相比对照分别降低了33.7%~93.7%和7.5%~40.9%，生物质炭添加抑制了酸性和石灰性紫色土硝化作用，在酸性紫色土中生物质炭对氮素硝化作用的抑制作用随施用量的增加而增强，在石灰性紫色土中无明显规律。（2）与对照相比，酸性紫色土N2O累计排放量在1%生物质炭（1%BC）和2%生物质炭（2%BC）处理下降幅分别为15.9%和27.7%，在5%生物质炭（5%BC）和10%生物质炭（10%BC）处理下增幅分别为60.1%和93.2%。石灰性紫色土生物质炭各处理N2O累积排放量均显著高于对照。（3）综合考虑酸性紫色土1%、2%生物质炭量施用下对硝化作用抑制和N2O减排综合效果最好，在石灰性紫色土中无明显抑制和减排效果。 相似文献
9.
The effects of incubation at 20°, 30° and 40°C and urea concentrations of 0, 50, 100 and 200 μg N/g soil on urea hydrolysis and nitrification were investigated in three Nigerian soils. At constant temperature urea hydrolysis and rate of NO3? accumulation increased with increasing rate of urea addition. Urea was rapidly hydrolyzed within 1 week of incubation. Nitrification in Apomu soil increased with increasing incubation temperature. Nitrification was slow in acid Nkpologu soil (pH 4.7). Texture, cation exchange capacity and C:N ratios of the soils were not related to urea hydrolysis or nitrification. Nitrite accumulation in these soils was insignificant. Soil pH was decreased by nitrification of hydrolyzed urea-N. 相似文献
10.
华北平原农田生态系统土壤C、N净矿化及尿素转化研究 总被引：4，自引：0，他引：4
以华北平原区4个农田生态系统[京郊蔬菜大棚(GH)和河北栾城(LF)、河北南皮(NF)、山东惠民(HF)3个粮田]为研究对象,采用室内好气、恒温、避光条件下培养30.d,对比研究了不同海拔和不同农业扰动强度下的农田生态系统中耕层(020.cm)土壤的净N矿化、净硝化、净C矿化以及尿素的转化,旨在探索人类农业扰动强度和地理海拔对土壤供N潜力和尿素N转化的影响。结果表明,4个地区的土壤供N潜力分别为:14.4、13.2,17.7和16.5.mg/kg,说明高度熟化的华北区农田土壤供N潜力相对稳定。以施用有机肥为主的蔬菜大棚和以施用化肥为主的粮田对土壤供N没有显著影响。农田土壤净矿化后的供N形式主要是NO3--N。以施用有机肥为主的蔬菜大棚积累了较高的土壤有机质和全N,但是土壤净C矿化以及施用尿素后CO2的排放量均低于以施用化肥为主的粮田。尿素在各区域农田土壤中水解转化后均主要以NO3--N形式存在,NO3--N占尿素水解后无机N增量的98%9～9%;华北平原农田生态系统施入尿素态N.30d后,水解成有效态无机N的转化率为63.4%8～3.2%,即每克尿素态N在京郊蔬菜大棚(GH)、栾城高产农田(LF)、南皮农田(NF)和惠民农田(HF)土壤中转化为NO3--N的量分别为0.69、0.82、0.64和0.63.g/kg,同时可使相应区域农田的CO2排放量分别增加CO21.20、1.360、.67和1.58.g/kg。 相似文献
11.
Purpose
Few studies have examined the effects of biochar on nitrification of ammonium-based fertilizer in acidic arable soils, which contributes to NO3 ? leaching and soil acidification.Materials and methods
We conducted a 42-day aerobic incubation and a 119-day weekly leaching experiment to investigate nitrification, N leaching, and soil acidification in two subtropical soils to which 300 mg N kg?1 ammonium sulfate or urea and 1 or 5 wt% rice straw biochar were applied.Results and discussion
During aerobic incubation, NO3 ? accumulation was enhanced by applying biochar in increasing amounts from 1 to 5 wt%. As a result, pH decreased in the two soils from the original levels. Under leaching conditions, biochar did not increase NO3 ?, but 5 wt% biochar addition did reduce N leaching compared to that in soils treated with only N. Consistently, lower amounts of added N were recovered from the incubation (KCl-extractable N) and leaching (leaching plus KCl-extractable N) experiments following 5 wt% biochar application compared to soils treated with only N.Conclusions
Incorporating biochar into acidic arable soils accelerates nitrification and thus weakens the liming effects of biochar. The enhanced nitrification does not necessarily increase NO3 ? leaching. Rather, biochar reduces overall N leaching due to both improved N adsorption and increased unaccounted-for N (immobilization and possible gaseous losses). Further studies are necessary to assess the effects of biochar (when used as an addition to soil) on N. 相似文献12.
Mohammad I. Khalil Muhammad S. Rahman Urs Schmidhalter Hans‐Werner Olfs 《植物养料与土壤学杂志》2007,170(2):210-218
A 90‐day laboratory incubation study was carried out using six contrasting subtropical soils (calcareous, peat, saline, noncalcareous, terrace, and acid sulfate) from Bangladesh. A control treatment without nitrogen (N) application was compared with treatments where urea, ammonium sulfate (AS), and ammonium nitrate (AN) were applied at a rate of 100 mg N (kg soil)–1. To study the effect of N fertilizers on soil carbon (C) turnover, the CO2‐C flux was determined at nine sampling dates during the incubation, and the total loss of soil carbon (TC) was calculated. Nitrogen turnover was characterized by measuring net nitrogen mineralization (NNM) and net nitrification (NN). Simple and stepwise multiple regressions were calculated between CO2‐C flux, TC, NNM, and NN on the one hand and selected soil properties (organic C, total N, C : N ratio, CEC, pH, clay and sand content) on the other hand. In general, CO2‐C fluxes were clearly higher during the first 2 weeks of the incubation compared to the later phases. Soils with high pH and/or indigenous C displayed the highest CO2‐C flux. However, soils having low C levels (i.e., calcareous and terrace soils) displayed a large relative TC loss (up to 22.3%) and the added N–induced TC loss from these soils reached a maximum of 10.6%. Loss of TC differed depending on the N treatments (urea > AS > AN >> control). Significantly higher NNM was found in the acidic soils (terrace and acid sulfate). On average, NNM after urea application was higher than for AS and AN (80.3 vs. 71.9 and 70.9 N (kg soil)–1, respectively). However, specific interactions between N‐fertilizer form and soil type have to be taken into consideration. High pH soils displayed larger NN (75.9–98.1 mg N (kg soil)–1) than low pH soils. Averaged over the six soils, NN after application of urea and AS (83.3 and 82.2 mg N (kg soil)–1, respectively) was significantly higher than after application of AN (60.6 mg N (kg soil)–1). Significant relationships were found between total CO2 flux and certain soil properties (organic C, total N, CEC, clay and sand content). The most important soil property for NNM as well as NN was soil pH, showing a correlation coefficient of –0.33** and 0.45***, respectively. The results indicate that application of urea to acidic soils and AS to high‐pH soils could be an effective measure to improve the availability of added N for crop uptake. 相似文献
13.
根据氮肥施入土壤后的转化特性进行氮肥的高效调控和管理是提高氮肥利用效率、缓解氮肥污染的重要措施。为探究不同氮肥在石灰性潮土中的转化特性差异及硫代硫酸铵（ammonium thiosulfate，ATS）作为氮肥调控剂对尿素氮转化的影响，该研究采用室内土壤培养（土壤水分含量为田间持水量的60%，温度25 ℃）试验方法，以尿素、硫酸铵、氯化铵和ATS作为供试肥料，比较4种氮肥施入石灰性潮土后的转化特性差异，并以ATS作为氮素调控剂，以单施尿素作为对照，探究尿素配施不同用量ATS对尿素氮转化的影响。结果表明，4种供试氮肥在石灰性潮土中的转化过程明显不同。尿素在石灰性潮土中的水解速率最快，硝化作用强度也最高，硫酸铵其次；氯化铵由于Cl-的硝化抑制作用，土壤表观硝化率在7～21 d显著低于尿素和硫酸铵（P＜0.05）；ATS施入土壤后，NH4+-N转化为NO2--N的速率最高，而NO2--N转化为NO3--N的速率最低，NH4+-N在土壤中的存留时间最长，出现峰值之后也一直保持最高的含量，表观硝化率最低。将ATS作为氮素调控剂与尿素配合施用，当其用量在60 mg/kg（含S量）以上时，既表现出了明显的抑制尿素水解的作用效果，也表现出了显著的硝化抑制作用（ P <0.05），且随着ATS用量的增加，抑制效应明显增强。这对于减少氮素损失，提高氮肥利用效率具有积极意义。但供试4种氮肥施入土壤后均出现了亚硝酸盐的累积，其中ATS处理的累积量显著高于尿素、硫酸铵和氯化铵（P＜0.05），累积持续时间也最长。ATS作为氮素调控剂调控氮素转化，也出现了类似的结果，且随着ATS用量增加，亚硝酸盐在土壤中存留时间明显延长，含量和峰值明显提高，出现峰值的时间也明显延后。 相似文献
14.
Pertti J. Martikainen 《Soil biology & biochemistry》1985,17(3):363-367
Nitrification was inhibited by ammonium sulphate and potassium sulphate added to soil from the organic horizon (pH 4.7) of a Myrtillus-type pine forest. Urea did not inhibit nitrification. Soil pH was slightly decreased by the salts but increased by urea. The salts increased soil electrical conductivity more than urea did. The inhibition of nitrification following salt treatments was probably due to a decrease in soil pH and not to osmotic effects. In acid conditions, the salts had a less inhibitory effect on CO2 production than on nitrification, indicating that nitrifying bacteria were more sensitive than other organisms to the salts. 相似文献
15.
K.L. Sahrawat 《Soil biology & biochemistry》1977,9(3):173-175
The effect of the biuret content (0.0, 1.0, 2.5, 5.0 and 10.0% of urea) on transformations of urea-N was studied in a sandy loam (pH 7.7). While biuret did not affect urea hydrolysis, it inhibited the conversion of NH+4 to NO?2 and the subsequent oxidation of NO?2 to NO?3. This resulted in the accumulation of larger amounts of both NH+4-N and NO?2-N in soil as compared to soil receiving urea alone. The results suggest that biuret impurity in urea fertilizer is likely to enhance nitrite toxicity. 相似文献
16.
Effects of repeated application of urea (UN) and calcium nitrate (CN) singly and together with crop straw biochars on soil acidity and maize growth were investigated with greenhouse pot experiments for two consecutive seasons. Canola straw biochar (CB), peanut straw biochar (PB) and wheat straw biochar (WB) were applied at 1% of dried soil weight in the first season. N fertilizers were applied at 200 mg N kg?1. In UN treatments, an initial rise in pH was subjected to proton consumption through urea hydrolysis, afterwards nitrification of NH4+ caused drastic reductions in pH as single UN had soil pH of 3.70, even lower than control (4.27) after the 2nd crop season. Post-harvest soil analyses indicated that soil pH, soil exchangeable acidity, NH4+, NO3? and total base cations showed highly significant variation under N and biochar types (P < 0.05). Articulated growth of plants under combined application with biochars was expressed by 22.7%, 22.5%, and 35.7% higher root and 25.6%, 23.8%, and 35.9% higher shoot biomass by CB, PB and WB combined with CN over UN, respectively. Therefore, CN combined with biochars is a better choice to correct soil acidity and improve maize growth than UN combined with biochars. 相似文献
17.
G. Nakos 《Soil biology & biochemistry》1977,9(6):423-426
Laboratory incubation experiments with and without added urea or NH4NO3 were performed on humus from stands of beech (Fagus silvatica) grown on soils from limestone, schists, flysch and peridotites and on humus from oak (Quercus conferta) stands on soils from limestone and schists.Beech and oak humus from stands grown on soils from limestone and flysch showed considerable nitrification with a concurrent high mobilization rate of the nutrient elements Ca, Mg and K, especially in the presence of increasing urea concentrations, but no net humus N mineralization was observed. Beech humus from stands grown on soils from schists and peridotites showed no nitrification and increasing concentrations of added urea did not modify their inability to nitrify. Non-nitrifying types of humus showed considerable ammonification but their Ca, Mg and K mobilization rates were about one-tenth those observed in nitrifying humus and were inversely correlated with urea concentrations.Exchangeable Al3+ and extractable Mn were present in high concentrations in the underlying inorganic soils in all cases where nitrification was absent from the overlying humus but addition of 500 parts Al3+ and 1000 parts Mn/106 separately or in combination to a nitrifying humus failed to inhibit nitrification.An interpretation of these findings is attempted with reference to the possibility of absence of nitrification in climax vegetations and the preference of certain forest species for NH+4 or NO?3. 相似文献
18.
Pertti J. Martikainen 《Soil biology & biochemistry》1984,16(6):577-582
The effects of seven different fertilization treatments on nitrification in the organic horizons of a Myrtillus-type (MT) and a Calluna-type pine forest in southern Finland were studied. No (NO?3 + NO?2)-N accumulated in unfertilized soils during 6 weeks at 14 or 20°C in the laboratory. Net nitrification was stimulated by urea in both soils (but more in the MT pine forest soil) and to a lesser degree by wood ash but not by ammonium nitrate or nitroform (ureaformaldehyde). Nitrification was not detected in nitroform fertilized soils although ammonium accumulation was high during incubation. In the MT pine forest soil, net nitrification appeared to be stimulated by apatite, biotite and micronutrients. Nitrapyrin inhibited nitrification indicating that it was carried out by autotrophic nitrifiers. In the urea-fertilized MT pine forest soil, nitrification took place at an incubation temperature of 0°C. Accumulation of (N0?3 + NO?2)-N was highest in soil sampled at < 10°C. 相似文献
19.
《Communications in Soil Science and Plant Analysis》2012,43(7):585-599
Abstract Early spring application of N to Iowa sandy, leachable soils results in reduced sweet corn yields and kernel protein content. Normally, split N applications are used to coincide with crop N demand. Our objectives were to determine if nitrapyrin, a nitrification inhibitor, applied with urea would provide high yields and kernel protein levels when applied at planting. Nitrogen rate increased yield, ear leaf N concentration, and kernel protein content in 1976 and 1978, with the optimum rate dependent on the year and soil N residual. Urea, with or without nitrapyrin, significantly enhanced yield 13%, early leaf N concentration 17%, and kernel protein content 9% as compared with Ca(NO3)2 for both years. High leaching loss of NO3‐N occurred with the Ca(NO3)2 source as compared with urea alone. Kernel protein concentration correlated well with ear leaf N concentration (r = .74) and yield (r = .61). Ear leaf K content was not affected by N rate or source, but Ca(NO3)2 enhanced uptake of Ca and Mg as compared with the urea sources. Urea, with nitrapyrin, decreased leaf Mg content in 1978, but not in 1976, as compared with urea alone. 相似文献
20.
Mayela MONGE-MU&#;OZ Segundo URQUIAGA Christoph M&#;LLER Juan Carlos CAMBRONEROHEINRICHS Mohammad ZAMAN Cristina CHINCHILLA-SOTO Azam BORZOUEI Khadim DAWAR Carlos E. RODR&#;GUEZ-RODR&#;GUEZ Ana Gabriela P&#;REZ-CASTILLO 《土壤圈》2021,31(2):303-313
In the tropics,frequent nitrogen(N)fertilization of grazing areas can potentially increase nitrous oxide(N2O)emissions.The application of nitrification inhibitors has been reported as an effective management practice for potentially reducing N loss from the soil-plant system and improving N use efficiency(NUE).The aim of this study was to determine the effect of the co-application of nitrapyrin(a nitrification inhibitor,NI)and urea in a tropical Andosol on the behavior of N and the emissions of N2O from autotrophic and heterotrophic nitrification.A greenhouse experiment was performed using a soil(pH 5.9,organic matter content 78 g kg-1,and N 5.6 g kg-1)sown with Cynodon nlemfuensis at 60%water-filled pore space to quantify total N2O emissions,N2O derived from fertilizer,soil ammonium(NH4+)and nitrate(NO3-),and NUE.The study included treatments that received deionized water only(control,NI).No significant differences were observed in soil NH4+content between the UR and UR+NI treatments,probably because of soil mineralization and NO3-produced by heterotrophic nitrification,which is not effectively inhibited by nitrapyrin.After 56 d,N2O emissions in UR(0.51±0.12 mg N2O-N concluded that the soil organic N mineralization and heterotrophic nitrification are the main processes of NH4+and NO3-production.Additionally,it was found that N2O emissions were partially a consequence of the direct oxidation of the soil's organic N via heterotrophic nitrification coupled to denitrification.Finally,the results suggest that nitrapyrin would likely exert significant mitigation on N2O emissions only if a substantial N surplus exists in soils with high organic matter content. 相似文献