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1.
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   

2.
Steaming of narrow soil bands prior to sowing is a new technique that reduces the need for intra-row weeding in herbicide-free row crops. However, the steam treatment may eliminate both weed seeds and non-target soil organisms, thereby affecting the nutrient cycling in the soil. This study tested the effect of band-steaming on N and C dynamics in a sandy loam soil that was steamed in situ to maximal temperatures of 70–90°C using a prototype band-steamer. Soil samples (0–5 cm depth) were collected during 90 days from band-steamed soil, undisturbed control soil, and control soil treated just mechanically with the band-steamer. In the steamed soil, ammonium concentrations increased from 1.1 to 20.3 μg NH 4 + -N g?1 dry weight during 28 days. This coincided with an immediate and persistent inhibition of potential nitrification (33–61% inhibition during 90 days). Assays of the temperature response of potential nitrification confirmed the temperature sensitivity and showed an optimum temperature of 27.1°C and a temperature coefficient (Q 10) of 1.9. The effects of band-steaming on concentrations of nitrate and water-soluble carbon were divergent and stimulatory, respectively, but generally not statistically significant. Mechanical effects of band-steaming were negligible. The observed ammonium surplus could be of agronomic benefit and should be evaluated in integrated studies of the effects of band-steaming on crop growth and plant N uptake.  相似文献   

3.
Nitrogen mineralization and immobilization were investigated in two soils incubated with ammonium sulphate or pig slurry over a range of temperatures and moisture contents. A reduction in the mineralization of soil organic N was observed in soils incubated with 100 μg NH4+-Ng?1 soil as ammonium sulphate at 30°C but not at lower temperatures. Addition of 100 μg NH4+-N g?1 soil as pig slurry resulted in a period of nett immobilization lasting up to 30 days at 5°C. Although the length of the immobilization phase was shorter at higher temperatures the total N immobilized was similar. The subsequent rate of mineralization in slurry-treated soils was not significantly greater (P = 0.05) than in untreated soils. There was no evidence of any subsequent increased mineralization arising from the immobilized N or slurry organic N for up to 175 days. The rate of immobilization was found to increase with increasing moisture content, though the period of nett immobilization was shorter, so that the amount of N immobilized was similar over a range of moisture contents from 10 to 40%. Approximately 40% of the NH4+-N in the slurry was immobilized under the incubation conditions used.  相似文献   

4.
The effects of temperature, moisture content and the addition of pig slurry on nitrification in two soils were studed. There was no accumulation of NO2?-N under the incubation conditions investigated and the accumulation of NO3?-N was linear for additions of 50–250 μg NH4+-N g? soil, either as ammonium sulphate or as pig slurry. Nitrate formation was treated as a single step, zero order process to enable a rate constant to be calculated. Nitrification rate increased with increasing moisture content up to the highest level tested, soil water potential ?8.0 kPa, corresponding to approximately 60% of water holding capacity in both soils. Measurable nitrification was found in both soils at the lowest moisture content (soil water potential ?1.5 MPa) and temperature (5° C) tested. The nitrification rate constant in soils treated with 50 μg NH4+-N g? soil was not significantly affected (P = 0.05) by the form of ammonium added. Addition of 250 μg NH4+-N as ammonium sulphate caused a marked inhibition of nitrification at all moisture contents and temperatures. Addition of 250 μg NH4+-N as pig slurry caused a marked increase in nitrification rate, the increase being greater at the higher temperatures and moisture contents.  相似文献   

5.
Survival ofEscherichia coli was studied in water from the Great Salt Lake, a highly saline lake with an ionic composition much like sea water. Samples used were from the most concentrated north arm (343.1 g l?1 solids) and the less concentrated south arm (about 113 g l?1 solids). At temperatures from 20°C to 9°C the bacterial death rate (k) for the north arm was ?0.17 log day?1 and the south arm and 1:3 dilution ?0.28 log day?1. Above 9°C the rate of death increased approximately exponentially and at 19°C the rate of death increased approximately exponentially and at 19°C the death rate was ?1.31 log day?1 in the north arm and ?0.98 log day?1 in the lower salinity water. These rates fall within those reported for sea water and are much higher than fresh water. Possible causes of death are discussed with the most likely being the high concentrations of minor elements or osmotic stress. The survival characteristics ofE. coli in waters with a sea water-like composition should require the same health concern as sea water regardless of the actual concentration of salt. High salt water of other ionic composition may behave differently, however.  相似文献   

6.

Purpose

Better understanding of N transformations and the regulation of N2O-related N transformation processes in pasture soil contributes significantly to N fertilizer management and development of targeted mitigation strategies.

Materials and methods

15N tracer technique combined with acetylene (C2H2) method was used to measure gross N transformation rates and to distinguish pathways of N2O production in two Australian pasture soils. The soils were collected from Glenormiston (GN) and Terang (TR), Victoria, Australia, and incubated at a soil moisture content of 60% water-filled pore space (WFPS) and at temperature of 20 °C.

Results and discussion

Two tested pasture soils were characterized by high mineralization and immobilization turnover. The average gross N nitrification rate (ntot) was 7.28 mg N kg?1 day?1 in TR soil () and 5.79 mg N kg?1 day?1 in GN soil. Heterotrophic nitrification rates (nh), which accounting for 50.8 and 41.9% of ntot, and 23.4 and 30.1% of N2O emissions in GN and TR soils, respectively, played a role similar with autotrophic nitrification in total nitrification and N2O emission. Denitrification rates in two pasture soils were as low as 0.003–0.004 mg N kg?1 day?1 under selected conditions but contributed more than 30% of N2O emissions.

Conclusions

Results demonstrated that two tested pasture soils were characterized by fast N transformation rates of mineralization, immobilization, and nitrification. Heterotrophic nitrification could be an important NO3?–N production transformation process in studied pasture soils. Except for autotrophic nitrification, roles of heterotrophic nitrification and denitrification in N2O emission in two pasture soils should be considered when developing mitigation strategies.
  相似文献   

7.
The total mineralization of nitrogen in the AO-A1 (0–6 cm), A1 (6–11 cm), and A2 (11–21 cm) horizons of a soddy pale-podzolic soil under an oxalis birch forest in Yaroslavl oblast was measured from May to November in 2009 and 2010 and comprised 6.7 ± 0.9, 3.0 ± 0.4, and 5.5 ± 0.6 g of N/m2 in 2009 and 5.6 ± 0.5, 2.5 ± 0.2, and 2.1 ± 0.5 g of N/m2 in 2010, respectively. The total nitrification reached 0.4 ± 0.1, 1.1 ± 0.2, and 1.4 ±0.1 g of N/m2 in 2009 and 1.0, 0.6, and 0.7 g of N/m2 in 2010. Overall, the amount of mineralized nitrogen in the 21-cm-deep soil layer in 2009 and 2010 constituted 15.2 ± 1.1 and 10.2 ± 0.7 g of N/m2, respectively. The contribution of nitrification to the nitrogen mineralization amounted to 20%. The seasonal variations in the soil temperature and moistening affected the concentrations of ammonium in the upper horizons and the accumulation of ammonium in the AO-A1 and A1 horizons. The combined effect of the temperature and moisture controlled the ammonification in the AO-A1 horizon (R = 0.83 at p = 0.16 in 2010), the nitrification in all the studied horizons (R = 0.86 at p= 0.13 in 2009), and the ammonia emission from the soil surface (R = 0.92 at p = 0.06 in 2010). A correlation between the seasonal dynamics of the ammonification and the CO2 emission was found for the AO-A1 horizon (r = 0.64 at p = 0.16 in 2010) and was absent in the deeper layers of the soil profile. The nitrogen losses from the soil surface due to the ammonia emission in the investigated periods reached 95 ± 31 g of N/ha (2009) and 33 ± 30 g of N/ha (2010).  相似文献   

8.
The excellent bactericidal performance of silver nanoparticles (Ag NPs) has led to their wide applications, resulting in increasing concerns about their potential environmental impacts. This study evaluated the influences of different concentrations of Ag NPs (0, 1, 10, and 100 μg g-1 dry soil) on the ammonia-oxidizing microorganisms in soil at cultivation temperatures of 25 and 5℃ for 37 d. The results showed that 1 μg g-1 dry soil of Ag NPs had no acute effects on the ammonia-oxidizing microorganisms. However, 10 and 100 μg g-1 dry soil of Ag NPs levels were found to significantly inhibit the activities of soil nitrification, with a decrease of 69.89% and 94.55%, respectively, at 25℃ and 61.65% and 83.79%, respectively, at 5℃ compared to the control (0 μg g-1 dry soil of Ag NPs). These levels of Ag NPs also obviously decreased soil urease activity from about 380.47 ±0.07 (at 5℃) and 529.76 ±13.44 (at 25℃) mg N g-1 dry soil d-1 to 61.70 ±2.97 and 68.29 ±8.22 mg N g-1 dry soil d-1, respectively, after 37 d of cultivation. Quantitative polymerase chain reaction showed the abundance of ammonia-oxidizing archaea and bacteria. For the same exposure time, the effects of Ag NPs on the activities of ammonia-oxidizing microorganisms and urease decreased with decreasing temperature. The threshold concentration of Ag NPs that induced negative effects on ammonia-oxidizing microorganisms was higher at 5℃ than at 25℃. Therefore, the temperature has a major impact on the toxicity of Ag NPs to ammonia-oxidizing microorganisms and on the urease activity, with toxicity being reduced with decreasing temperature.  相似文献   

9.
Abstract. Gross N mineralization and nitrification rates were measured in soils treated with dairy shed effluent (DSE) (i.e. effluent from the dairy milking shed, comprising dung, urine and water) or ammonium fertilizer (NH4Cl) under field conditions, by injecting 15N-solution into intact soil cores. The relationships between gross mineralization rate, microbial biomass C and N and extracellular enzyme activities (protease, deaminase and urease) as affected by the application of DSE and NH4Cl were also determined. During the first 16 days, gross mineralization rate in the DSE treated soil (4.3–6.1 μg N g?1 soil day?1) were significantly (P 14;< 14;0.05) higher than those in the NH4Cl treated soil (2.6–3.4 μg N g?1 soil day?1). The higher mineralization rate was probably due to the presence of readily mineralizable organic substrates in the DSE, accompanied by stimulated microbial and extracellular enzyme activities. The stable organic N compounds in the DSE were slow to mineralize and contributed little to the mineral N pool during the period of the experiment. Nitrification rates during the first 16 days were higher in the NH4Cl treated soil (1.7–1.2 μg N g?1 soil day?1) compared to the DSE treated soil (0.97–1.5 μg N g?1 soil day?1). Soil microbial biomass C and N and extracellular enzyme activities (protease, deaminase and urease) increased after the application of the DSE due to the organic substrates and nutrients applied, but declined with time, probably because of the exhaustion of the readily available substrates. The NH4Cl application did not result in any significant increases in microbial biomass C, protease or urease activities due to the lack of carbonaceous materials in the ammonium fertilizer. However, it did increase microbial biomass N and deaminase activity. Significant positive correlations were found between gross N mineralization rate and soil microbial biomass, protease, deaminase and urease activities. Nitrification rate was significantly correlated to biomass N but not to the microbial biomass C or the enzyme activities. Stepwise regression analysis showed that the variations of gross N mineralization rate was best described by the microbial biomass C and N.  相似文献   

10.
To date, occurrence and stimulation of different nitrification pathways in acidic soils remains unclear. Laboratory incubation experiments, using the acetylene inhibition and 15N tracing methods, were conducted to study the relative importance of heterotrophic and autotrophic nitrification in two acid soils (arable (AR) and coniferous forest) in subtropical China, and to verify the reliability of the 15N tracing model. The gross rate of autotrophic nitrification was 2.28 mg?kg?1?day?1, while that of the heterotrophic nitrification (0.01 mg?kg?1?day?1) was negligible in the AR soil. On the contrary, the gross rate of autotrophic nitrification was very low (0.05 mg?kg?1?day?1) and the heterotrophic nitrification (0.98 mg?kg?1?day?1) was the predominant NO3 ? production pathway accounting for more than 95 % of the total nitrification in the coniferous forest soil. Our results showed that the 15N tracing model was reliable when used to study soil N transformation in acid subtropical soils.  相似文献   

11.
Surface mineral horizons from four ecosystems sampled in the northwestern Italian Alps were incubated at −3 and +3°C to simulate subnivial and early thaw period temperatures for a seasonally snow-covered area. The soil profiles at these sites represent extreme examples of management, grazed meadow (site M) and extensive grazing beneath larch (site L) or naturally disturbed by avalanche and colonized by alder (site A) and the expected forest climax vegetation beneath fir (site F). Changes in labile pools of nitrogen (N) and phosphorus (P) were active at all sites at both temperatures during 14 days of laboratory incubation. Ammonium was the dominant inorganic form of total dissolved N (TDN), being equivalent to 1.8–9.8 g N m−2 within the mineral horizon. Gross rates of ammonification were similar at the two temperatures but significantly (p<0.05) greater in soil from beneath fir than in the other three. Nitrification occurred in all soils and displayed a wide range in rates, from 2 to 85 mg N m−2 day−1, and was least in the two most acid soils, A and F. Immobilization of NH4 + as microbial N was greater in the fir soil than in the other three. Also, the fir soil showed greatest gross ammonification and least accumulation of NO3 − and greatest tendency to retain N. This high N retention capacity in the climax ecosystem contrasted with the managed systems characterized by higher nitrification rates and greater potential spring NO3 − loss. Dissolved organic N ranged between 30 and 50% of the TDN, while dissolved organic P was greater than 70% of total dissolved P (TDP). The dissolved organic compounds were important components of the labile pool, in equilibrium with a large reserve of organic N, and may significantly contribute to the soil N availability at low temperatures.  相似文献   

12.
The influence of the addition of anthracene (1 μg anthracene g?1 soil) in N transformations following (15NH4)2SO4 fertilization (200 mg N g?1 soil) was investigated in wheat pots by quadrapole mass-spectrometry. The dry matter yield at harvesting (after 16 days) was not statistically affected (P=0.05) by anthracene addition. The total amount of N from the fertilizer taken up by wheat seedings in 16 days was 29 and 26.8% of the added N in the absence and in the presence of anthracene, respectively, but the difference was not significantly different at level P=0.05. In order to investigate more deeply the effect of anthracene on the N cycle in the soil-plant system, the first-order rate constants of N mineralization, N immobilization, nitrification and N plant uptake have been determined according to a 15N + 14N soil-plant model. The comparison of the constants showed that organic N mineralization, nitrification and plant uptake proceeded at the same rate, while a small different rate (P=0.05) was shown by N immobilization. In fact, the N immobilization constant increased from 0.14±0.012 to 0.21±0.014 day?1 as a consequence of anthracene addition.  相似文献   

13.
The herbicide glyphosate was sprayed aerially on a section of conifer forest in Atlantic Canada that had been previously clearcut and reforested. Glyphosate was then tested for effects on ammonification, nitrification, and denitrification for a period of 8 months by comparing microbial activity in treated and untreated zones of the clay loam forest soil and the overlying decomposing litter, both with a pH of 3.8. With ammonification, there was generally a stimulation of activity in both the forest litter (FL) and forest soil (FS) that had been exposed to glyphosate during spraying. Nitrification rates in FL and FS were very low and glyphosate had no appreciable stimulatory or inhibitory effect on nitrification. Although glyphosate stimulated denitrification in a few instances, it generally had no significant effect on denitrification activity in FL and FS exposed during spraying. With all processes, microbial activity in FL was significantly greater than that in FS. Laboratory bioassays were also performed with FL and FS, as well as two silt loam (pH 5.8 and 6.4) and one sandy loam (pH 6.8) agricultural soils, using glyphosate concentrations up to 200 times higher than field application rates. With ammonification and denitrification, glyphosate generally stimulated activity at all levels tested and in all soil used. Glyphosate stimulated ammonification by 50% at concentrations ranging from 140 to 550 μg g?1 for the soils and >4000 μg g?1 for FL. With denitrification, the corresponding herbicide levels were approximately 2250 μg g?1 for FS, > 10,000 for FL, and 450 for an agricultural soil. With nitrification, it was estimated that glyphosate concentrations greater than 1000 to 2000 μg g?1 would be required to cause a 50% inhibition of activity. The careful use of glyphosate in forestry should have no toxic effects on N cycling in soils.  相似文献   

14.
The effects of 10 urease inhibitors on nitrification in soils were studied by determining the effects of 10 and 50 parts/106 (soil basis) of each inhibitor on the amounts of nitrate and nitrite produced when soils treated with ammonium sulfate (200 μg of ammonium N/g of soil) were incubated (30°C) under aerobic conditions for 14 days. The urease inhibitors used (catechol. hydroquinone, p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone. 2,6-dimethyl-p-benzoquinone. 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone. sodium p-chloromercuribenzoate, and phenylmercuric acetate) were those found most effective in previous work to evaluate more than 130 compounds as soil urease inhibitors. Their effects on nitrification were compared with those of three compounds patented as soil nitrification inhibitors (N-Serve. AM. and ST).Most of the urease inhibitors studied had little effect on nitrification when applied at the rate of 10 μg/g of soil. but had marked inhibitory effects when applied at the rate of 50 μg/g of soil. None inhibited nitrification as effectively as N-Serve. but phenylmercuric acetate inhibited nitrification more effectively than did AM or ST when applied at the rate of 10 μg/g of soil. Phenylmercuric acetate, 2,5-dimethyl-p-benzoquinone, and 2,6-dimethyl-p-benzoquinone had very marked effects on nitrification when applied at the rate of 50 μg/g of soil.  相似文献   

15.
Zinc as ZnSO4 was added to three soils at rates of 0, 10, 100 and 1000 μg Zn g?1 soil. The soils were uniformly treated with 100 μg Ng?1 as nh4cl, incubated at 30°C and NH4+-N and (NO3? + NO2?)-N determined weekly for 7 weeks. Nitrification in all three soils was totally inhibited by 1000 μg Zn g?1. At the 100 μg Zn g?1 rate, nitrification was significantly reduced in two of the three soils during some part of the incubation. This differential effect on nitrification at the 100 μg Zn g?1 rate was related to differences in soil properties. These results imply that, with respect to nitrification, care should-be taken not to apply Zn-containing materials indiscriminately to soils.  相似文献   

16.
Emissions of nitrous oxide (N2O), a potent greenhouse gas, from agricultural soil have been recognized to be affected by nitrogen (N) application and temperature. Most of the previous studies were carried out to determine effects of temperature on N2O emissions at a fixed N application rate or those of N application rates at a specific temperature. Knowledge about the effects of different ammonium (NH4+) application rates and temperatures on N2O emissions from tropical agricultural soil and their interactions is limited. Five grams of air-dried sandy loam soil, collected in Central Vietnam, were adjusted to 0, 400, 800 and 1200 mg NH4-N kg–1 soil (abbreviated as 0 N, 400 N, 800 N and 1200 N, respectively) at 60% water holding capacity were aerobically incubated at 20°C, 25°C, 30°C or 35°C for 28 days. Mineral N contents and N2O emission rates were determined on days 1, 3, 5, 7, 14, 21 and 28. Cumulative N2O emissions for 28 days increased with increasing NH4+ application rates from 0 to 800 mg N kg–1 and then declined to 1200 mg N kg–1. Cumulative N2O emissions increased in the order of 35°C, 20°C, 30°C and 25°C. This lowest emission at 35°C occurred because N2O production was derived only from autotrophic nitrification while other N2O production processes, e.g., nitrifier denitrification and coupled nitrification-denitrification occurred at lower temperatures. More specifically, cumulative N2O emissions peaked at 800 N and 25°C, and the lowest emissions occurred at 1200 N and 35°C. In conclusion, N2O emissions were not exponentially correlated with NH4+ application rates or temperatures. Higher NH4+ application rates at higher temperatures suppressed N2O emissions.  相似文献   

17.
Examination of three forest soils from Malaysia using the soil incubation technique suggests that nitrification was not inhibited in these oligotrophic soils. Nitrification rates were between 40 and 750 ngN produced g?1 dry weight soil day?1 of incubation. Addition of phenolic metabolites (tannic acid) and leaf filtrates from hill and lowland forest litter did not significantly inhibit nitrification. Addition of sucrose (1% w/w carbon source) decreased nitrification but not ammonification.  相似文献   

18.
The effects of temperature and water potential on nitrification were investigated in two Iowa soils treated with Stay‐N 2000. The soils were incubated at 10, 20, and 30 °C after soil water potentials of ?1, ?10, or ?60 kPa were applied to each soil. A first‐order equation was used to calculate the maximum nitrification rate (K max), duration of lag period (t′), period of maximum nitrification (Δt), and termination period of nitrification (t s). The highest K max were 18 and 24 mg kg?1 d?1 nitrate (NO3 ?)–nitrogen (N), respectively, at 30 °C and ?10 kPa in both the Nicollet (fine‐loamy, mixed, superactive, mesic Aquic Hapludoll) and Canisteo (fine‐loamy, mixed, superactive, calcareous, mesic Typic Endoaquoll) soils and reduced to 4 and 16 mg kg?1 d?1 NO3 ?‐N when Stay‐N 2000 was added. The extension of t′ due to the addition of Stay‐N 2000 was as high as 7 d in the Nicollet soil at 10 °C and ?1 kPa and as little as 2 d in the Canisteo soil at 20 °C and ?10 kPa.  相似文献   

19.
We studied the changes in composition of the soil solution following mineralization of N at different temperatures, with a view to using TDR to calculate temperature coefficients for the mineralization of N. Mineralization from soil organic nitrogen was measured during aerobic incubation under controlled conditions at six temperatures ranging from 5.5 to 30°C, and at constant water content in a loamy sand soil. We also monitored during the incubation the concentrations of SO42–, Cl–, HCO3–, Ca2+, K+, Mg2+ and Na+, and the pH and the electrical conductivity in 1:2 soil:water extracts. Zero‐order N mineralization rates ranged between 0.164 at 5.5°C and 0.865 mg N kg?1 soil day?1 at 30°C. There was a significant decrease in soil pH during incubation, of up to 0.6 pH units at the end of the incubation at 30°C. The electrical conductivity of the soil extracts increased significantly at all temperatures (the increase between the start and the end of the incubation was 4‐fold at 30°C) and was strongly correlated with N mineralization. The ratio of bivalent to monovalent cations increased markedly during mineralization (from 2.2 to 5.9 at 30°C), and this increase influenced the evolution of the electrical conductivity of the soil solution through the differences in molar‐limiting ion conductivity between mainly Ca2+ and K+. Zero‐order mineralization rate constants, k, for NO3– concentrations calculated from TDR varied between 0.070 (at 5.5°C) and 0.734 mg N kg?1 soil day?1 (at 30°C), which were slightly smaller, but in the same range, as the measured rates. Underestimation of the measured N mineralization rates was due, at least in part, to differences in cation composition of the soil solution between calibration and mineralization experiments. A temperature‐dependence model for N mineralization from soil organic matter was fitted to both the measured and the TDR‐calculated mineralization rates, k and kTDR, respectively. There were no significant differences between the model parameters from the two. Our results are promising for further use of TDR to monitor soil organic N mineralization. However, the influence of changing cation ratios will also have to be taken into account when trying to predict N mineralization from measured electrical conductivities.  相似文献   

20.
Sludge derived from cow manure anaerobically digested to produce biogas (methane; CH4) was applied to maize (Zea mays L.) cultivated in a nutrient-low, alkaline, saline soil with electrolytic conductivity 9.4 dS m?1 and pH 9.3. Carbon dioxide (CO2) emission increased 3.1 times when sludge was applied to soil, 1.6 times when cultivated with maize and 3.5 times in sludge-amended maize cultivated soil compared to the unamended uncultivated soil (1.51 mg C kg?1 soil day?1). Nitrous oxide (N2O) emission from unamended soil was -0.0004 μg nitrogen (N) kg?1 soil day?1 and similar from soil cultivated with maize (0.27 μg N kg?1 soil day?1). Application of sludge increased the N2O emission to 4.59 μg N kg?1 soil day?1, but cultivating this soil reduced it to 2.42 μg N kg?1 soil day?1. It was found that application of anaerobic digested cow manure stimulated maize development in an alkaline saline soil and increased emissions of CO2 and N2O.  相似文献   

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