14C-tracer technique and closed incubation method were used to study straw 14C decomposition and distribution in different fractions of newly formed humus under different moisture regimes. Decomposition of straw 14C w...14C-tracer technique and closed incubation method were used to study straw 14C decomposition and distribution in different fractions of newly formed humus under different moisture regimes. Decomposition of straw 14C was faster during the initial days, and slower thereafter. Decay rate constants of straw 14C varied from 3.29x10-3 d-1 to 7.06x10-3 d-1. After 112 d incubation, the amount of straw 14C mineralized was 1.17～1.46 times greater in submerged soils than in upland soils. of the soil residual 14C, 9.08%～15.73%was present in humic acid (HA) and 31.01%～37.62% in fulvic acid (FA). Submerged condition favored the formation of HA, and HA/FA ratio of newly formed humus (labelled) was greater in submerged soils than in upland soils. Clay minerals affected the distribution of straw 14C in different humus fractions. Proportion of 14C present in HA to 14C remaining in soil was greater in Vertisol than in Ultisol.展开更多
Elovich, parabolic diffusion, power function and exponential equations were used to describe K desorptionkinetics of 12 soils in a constant electric field of electro-ultrafiltration (EUF). Results showed that the Elov...Elovich, parabolic diffusion, power function and exponential equations were used to describe K desorptionkinetics of 12 soils in a constant electric field of electro-ultrafiltration (EUF). Results showed that the Elovich,parabolic diffusion and power function equations could describe K desorption kinetics well owing to their highcorrelatfon coefficients and low standard errors; but the exponential equation was not suitable to be usedin this study due to its relatively low correlation coefficients and relatively high standard errors. This workestablished successfully the relationships between the constants (slope or intercept) of kinetic equations andthe barley responses to K fertilizer in the multiple-site field experiments and K-supplying status of soils, theconstants of Elovich, parabolic diffusion and power function equations were very significantly or significantlycorrelated to the soil available K, relative yield of barley and K uptake of barley in NP plot. It was suggestedthat the kinetic equation constants could be used to estimate K-supplying power of soils.展开更多
Kdesorption from soils in a constant electric field(field strength:44.5Vcm-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt = k(D-d)2. From thee...Kdesorption from soils in a constant electric field(field strength:44.5Vcm-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt = k(D-d)2. From theequation, such kinetic parameters relating to K desorption from soils as the maximum desorbable quantity D, quantity of K desorbed within 40 minutes d40, initial desorption rate Vo, desorption rate constant k and half-time t1/2 could be calculated. An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established. Vo, D and d40 were significantly correlated with barley relative yield, K uptake by barley and the content of soil available potassium. The rate constants of K desorption varied between 4.42 × 10-4-1.80 × 10-3kg mg-1 min-1 and highly correlated with the relative yield of barley. The kinetic parameters including Vo, D, d40 and k were successfully used to estimate the K-supplying power of soils.展开更多
Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Pr...Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Province in a constant electric field (44.4 V/ cm) of EUF. Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best, as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE). The first-order, two-constant and parabolic diffusion equations also described the K desorption kinetics well, as showed by the relatively high correlation coefficients and relatively low standard errors. The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error. However, the exponential equation could not be used to describe the K desorption kinetics, due to the lowest correlation coefficient and the highest standard error.展开更多
Sulfur transformation in 3 soils maintained in a closed incubation system and its availability to plants were investigated using carrier-free35S-SO42- and 35S-labeled ryegrass straw. For carrier-free Na235SO4 treatmen...Sulfur transformation in 3 soils maintained in a closed incubation system and its availability to plants were investigated using carrier-free35S-SO42- and 35S-labeled ryegrass straw. For carrier-free Na235SO4 treatment, 78%, 70% and 64% of 35S applied were found in Ca (H2PO4)2-extractble S fraction 14%, 5% and 7% in slowly soluble inorganic S, 11%, 15% and 18% in C-O-S, 5%, 7% and 6% in C-bonded S, and 5%,7% and 6% in unidentified organic S 120 days after incubation in black soil, cinnamon soil and chestnut soil, respectively. Most of 35S uptake by plants came from extractable 35S42-, and little from C-O-35S and C-bonded 355. In the treatment with 35S-labeled straw, 51%, 46% and 36% of 355 incorporated were found in C a (H2PO4)2 -extractable S fraction) 7%, 6% and 7% in slowly solub ie inorganic S, 13%, 15% and 18% in C-O-S, 8%, 8% and 6% in C-bonded S, and 18%, 25% and 35% in unidentified organic S at the end of incubation in above-mentioned three soils, respectively. Higher availability of C-O-35S, C-bonded 35S and unidentified organic 35S from 35S-labeled straw was observed in 35S-labeled straw treatment compared to carrier-free Na235SO4 treatment.展开更多
Experiments including two in laboratory and one in greenhouse were carried out to study non- exchangeable magnesium release from fluvo-aquic soils sampled from Daxing and changping counties located in the suburbs of B...Experiments including two in laboratory and one in greenhouse were carried out to study non- exchangeable magnesium release from fluvo-aquic soils sampled from Daxing and changping counties located in the suburbs of Beijing and Mg relative availability of the two soils to plants. In a batch experiment in laboratory the soils were incubated under wet conditions and alternation of dry and wet conditions and determined for amount of Mg released at the 4th, 8th and 12th week, respectively, after extraction of exchangeable Mg with 1 mol L-1 NH4Ac. The amount of Mg released from the soil of Daxing was higher than from the soil of Changping, which was in accordance with the fact that the soil of Daxing had higher contents of all forms of Mg than that of Changping. There was little difference in Mg release from soils between wet conditions and alternation of dry and wet conditions. About 1%~2% of the total non-exchangeable Mg might be released within 12 weeks of incubation, restoring about 30%~35% of the original soil exchangeable Mg. Results of the experiment on kinetics of Mg release from the soils through continuous extractions with 0.5 mol L-1 NH4Ac (pH 7.0) on a continuous flow apparatus in laboratory showed that Mg released rapidly in the beginning, decreased sharply with time and kept stable at 60 and 240 min for the soils of Changping and Daxing, respectively. Among the five mathematical models used to describe the kinetics of Mg release, the parabolic diffusion equation best fitted the cumulative Mg release, indicating that diffusion of Mg out of the soils might be the controlling process. The experiment of exhaustive cropping with 1 crop of tomato (Lycopersicon esculentum Mill.) followed by six crops of corn (Zea mays L.) in greenhouse showed that soil exchangeable Mg decreased remarkably with cropping. After three crops, the percentage of the total plant Mg uptake that came from soil non-exchangeable Mg was 29.5% for the soil from Changping and 35% for the soil from Daxing. About 50% of the total Mg uptake by plants in the six crops was believed to come from the soil non-exchangeable Mg form.展开更多
A field experiment was conducted to investigate the variations in denitrification losses and N2O emissions from 4 different types of nitrogen fertilizers (urea, ammonium nitrate, ammonium bicarbonate, and calcium nitr...A field experiment was conducted to investigate the variations in denitrification losses and N2O emissions from 4 different types of nitrogen fertilizers (urea, ammonium nitrate, ammonium bicarbonate, and calcium nitrate) applied to the maize- fluvo-aquic soil system in the North China Plain by the method of intact soil core incubation and acetylene inhibition, and the responses of nitrogen fertilizers to maize grain yields. Results show that the denitrification loss from different nitrogen fertilizers ranged from 0.38-1.20 kg N ha-1, with no significant differences among different fertilizer treatments, and the N2O emission from 0.05-0.95 kg N ha-1, with a significant difference (P<0.05) among the treatments. The highest emission was from the treatment of ammonium nitrate, while the lowest from calcium nitrate. The nitrogen fertilizers increased the maize grain yield by 9.7-19.8% compared to control. But there were no significant differences in yield increase among the 4 types of nitrogen fertilizers. In comparison, urea had the best effect, whereas calcium nitrate had the least effect on increasing maize yield. The maize yield was 5.7% higher when urea was separately applied at 2 times than when it was applied at a time. In this case, however, the denitrification loss and the N2O emission were also increased by 4.05 and 1.84 kg N ha-1, respectively.展开更多
Four mathematical models were systematically evaluated in describing responses of four different cropsat 7 rates of nitrogen application. Residual sum of squares and a total point ranking method were used toassess the...Four mathematical models were systematically evaluated in describing responses of four different cropsat 7 rates of nitrogen application. Residual sum of squares and a total point ranking method were used toassess the model fitting for crop responses to nitrogen application. Sparrow’s inverse quadratic polynomialmodel performed the best.展开更多
The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of...The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of chlorophyll a, chlorophyll b and carotenoid in tobacco. At the same time, the activities of NR (nitrate reductase), INV(invertase) and root growth activity were also significantly enhanced. The exogenous glutamic, aspartate and phenylalanine all increased the amino acid contents of tobacco leaves. Of these three amino acids, glutamic had the greatest effect, the next was aspartate, and phenylalanine had the least effect. These three amino acids all had significantly increased the accumulation of amino acids in the leaves of individual plants of tobacco; and the magnitude of accumulation indicated aspartate > glutamic > phenylalanine.展开更多
The K+ adsorption kinetics of fluvo-aquic soil and cinnamon soil under different temperatureswere studied. The results showed: 1) The first order equations were the most suitable forfitting the adsorption under variou...The K+ adsorption kinetics of fluvo-aquic soil and cinnamon soil under different temperatureswere studied. The results showed: 1) The first order equations were the most suitable forfitting the adsorption under various temperature levels with constant K+ concentration indisplacing fluid. With temperature increasing, the fitness of Elovich equation increased,while those of power equation and parabolic diffusion equation decreased; 2)the apparentadsorption rate constant ka and the product of ka multiplied by the apparent equilibriumadsorption qincreased when temperature increased, while the apparent equilibrium adsorptionqreduced; 3)temperature influenced hardly the reaction order, the order of concentrationand adsorpton site were always 1 under various temperatures, if they were taken intoaccount simultaneously, the adsorption should be a two-order reaction process; 4)theGibbs free energy change △G of potassium adsorption were negative, ranged from -4444.56to -2450.63Jmol-1,and increased with temperature increasing, while enthalpy change △H,entropy change △S, apparent adsorption activation Ea, adsorption activation energy E1and desorption activation energy E2 were temperature-independent; 5)the adsorption wasspontaneous process with heat releasing and entropy dropping, fluvo-aquic soil releasedmore heat than cinnamon soil.展开更多
文摘14C-tracer technique and closed incubation method were used to study straw 14C decomposition and distribution in different fractions of newly formed humus under different moisture regimes. Decomposition of straw 14C was faster during the initial days, and slower thereafter. Decay rate constants of straw 14C varied from 3.29x10-3 d-1 to 7.06x10-3 d-1. After 112 d incubation, the amount of straw 14C mineralized was 1.17～1.46 times greater in submerged soils than in upland soils. of the soil residual 14C, 9.08%～15.73%was present in humic acid (HA) and 31.01%～37.62% in fulvic acid (FA). Submerged condition favored the formation of HA, and HA/FA ratio of newly formed humus (labelled) was greater in submerged soils than in upland soils. Clay minerals affected the distribution of straw 14C in different humus fractions. Proportion of 14C present in HA to 14C remaining in soil was greater in Vertisol than in Ultisol.
文摘Elovich, parabolic diffusion, power function and exponential equations were used to describe K desorptionkinetics of 12 soils in a constant electric field of electro-ultrafiltration (EUF). Results showed that the Elovich,parabolic diffusion and power function equations could describe K desorption kinetics well owing to their highcorrelatfon coefficients and low standard errors; but the exponential equation was not suitable to be usedin this study due to its relatively low correlation coefficients and relatively high standard errors. This workestablished successfully the relationships between the constants (slope or intercept) of kinetic equations andthe barley responses to K fertilizer in the multiple-site field experiments and K-supplying status of soils, theconstants of Elovich, parabolic diffusion and power function equations were very significantly or significantlycorrelated to the soil available K, relative yield of barley and K uptake of barley in NP plot. It was suggestedthat the kinetic equation constants could be used to estimate K-supplying power of soils.
文摘Kdesorption from soils in a constant electric field(field strength:44.5Vcm-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt = k(D-d)2. From theequation, such kinetic parameters relating to K desorption from soils as the maximum desorbable quantity D, quantity of K desorbed within 40 minutes d40, initial desorption rate Vo, desorption rate constant k and half-time t1/2 could be calculated. An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established. Vo, D and d40 were significantly correlated with barley relative yield, K uptake by barley and the content of soil available potassium. The rate constants of K desorption varied between 4.42 × 10-4-1.80 × 10-3kg mg-1 min-1 and highly correlated with the relative yield of barley. The kinetic parameters including Vo, D, d40 and k were successfully used to estimate the K-supplying power of soils.
文摘Elovicb, two-constant, parabolic diffusion, exponential, second-order, first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils df Zhejiang Province in a constant electric field (44.4 V/ cm) of EUF. Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best, as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE). The first-order, two-constant and parabolic diffusion equations also described the K desorption kinetics well, as showed by the relatively high correlation coefficients and relatively low standard errors. The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error. However, the exponential equation could not be used to describe the K desorption kinetics, due to the lowest correlation coefficient and the highest standard error.
文摘Sulfur transformation in 3 soils maintained in a closed incubation system and its availability to plants were investigated using carrier-free35S-SO42- and 35S-labeled ryegrass straw. For carrier-free Na235SO4 treatment, 78%, 70% and 64% of 35S applied were found in Ca (H2PO4)2-extractble S fraction 14%, 5% and 7% in slowly soluble inorganic S, 11%, 15% and 18% in C-O-S, 5%, 7% and 6% in C-bonded S, and 5%,7% and 6% in unidentified organic S 120 days after incubation in black soil, cinnamon soil and chestnut soil, respectively. Most of 35S uptake by plants came from extractable 35S42-, and little from C-O-35S and C-bonded 355. In the treatment with 35S-labeled straw, 51%, 46% and 36% of 355 incorporated were found in C a (H2PO4)2 -extractable S fraction) 7%, 6% and 7% in slowly solub ie inorganic S, 13%, 15% and 18% in C-O-S, 8%, 8% and 6% in C-bonded S, and 18%, 25% and 35% in unidentified organic S at the end of incubation in above-mentioned three soils, respectively. Higher availability of C-O-35S, C-bonded 35S and unidentified organic 35S from 35S-labeled straw was observed in 35S-labeled straw treatment compared to carrier-free Na235SO4 treatment.
文摘Experiments including two in laboratory and one in greenhouse were carried out to study non- exchangeable magnesium release from fluvo-aquic soils sampled from Daxing and changping counties located in the suburbs of Beijing and Mg relative availability of the two soils to plants. In a batch experiment in laboratory the soils were incubated under wet conditions and alternation of dry and wet conditions and determined for amount of Mg released at the 4th, 8th and 12th week, respectively, after extraction of exchangeable Mg with 1 mol L-1 NH4Ac. The amount of Mg released from the soil of Daxing was higher than from the soil of Changping, which was in accordance with the fact that the soil of Daxing had higher contents of all forms of Mg than that of Changping. There was little difference in Mg release from soils between wet conditions and alternation of dry and wet conditions. About 1%~2% of the total non-exchangeable Mg might be released within 12 weeks of incubation, restoring about 30%~35% of the original soil exchangeable Mg. Results of the experiment on kinetics of Mg release from the soils through continuous extractions with 0.5 mol L-1 NH4Ac (pH 7.0) on a continuous flow apparatus in laboratory showed that Mg released rapidly in the beginning, decreased sharply with time and kept stable at 60 and 240 min for the soils of Changping and Daxing, respectively. Among the five mathematical models used to describe the kinetics of Mg release, the parabolic diffusion equation best fitted the cumulative Mg release, indicating that diffusion of Mg out of the soils might be the controlling process. The experiment of exhaustive cropping with 1 crop of tomato (Lycopersicon esculentum Mill.) followed by six crops of corn (Zea mays L.) in greenhouse showed that soil exchangeable Mg decreased remarkably with cropping. After three crops, the percentage of the total plant Mg uptake that came from soil non-exchangeable Mg was 29.5% for the soil from Changping and 35% for the soil from Daxing. About 50% of the total Mg uptake by plants in the six crops was believed to come from the soil non-exchangeable Mg form.
基金The work was supported by the National Natural Sci-ence Foundation of China(49901010).
文摘A field experiment was conducted to investigate the variations in denitrification losses and N2O emissions from 4 different types of nitrogen fertilizers (urea, ammonium nitrate, ammonium bicarbonate, and calcium nitrate) applied to the maize- fluvo-aquic soil system in the North China Plain by the method of intact soil core incubation and acetylene inhibition, and the responses of nitrogen fertilizers to maize grain yields. Results show that the denitrification loss from different nitrogen fertilizers ranged from 0.38-1.20 kg N ha-1, with no significant differences among different fertilizer treatments, and the N2O emission from 0.05-0.95 kg N ha-1, with a significant difference (P<0.05) among the treatments. The highest emission was from the treatment of ammonium nitrate, while the lowest from calcium nitrate. The nitrogen fertilizers increased the maize grain yield by 9.7-19.8% compared to control. But there were no significant differences in yield increase among the 4 types of nitrogen fertilizers. In comparison, urea had the best effect, whereas calcium nitrate had the least effect on increasing maize yield. The maize yield was 5.7% higher when urea was separately applied at 2 times than when it was applied at a time. In this case, however, the denitrification loss and the N2O emission were also increased by 4.05 and 1.84 kg N ha-1, respectively.
文摘Four mathematical models were systematically evaluated in describing responses of four different cropsat 7 rates of nitrogen application. Residual sum of squares and a total point ranking method were used toassess the model fitting for crop responses to nitrogen application. Sparrow’s inverse quadratic polynomialmodel performed the best.
文摘The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of chlorophyll a, chlorophyll b and carotenoid in tobacco. At the same time, the activities of NR (nitrate reductase), INV(invertase) and root growth activity were also significantly enhanced. The exogenous glutamic, aspartate and phenylalanine all increased the amino acid contents of tobacco leaves. Of these three amino acids, glutamic had the greatest effect, the next was aspartate, and phenylalanine had the least effect. These three amino acids all had significantly increased the accumulation of amino acids in the leaves of individual plants of tobacco; and the magnitude of accumulation indicated aspartate > glutamic > phenylalanine.
基金supported by the National Science Foundation of China(49391600)the Society Commonweal Fund(2001DIA20024).
文摘The K+ adsorption kinetics of fluvo-aquic soil and cinnamon soil under different temperatureswere studied. The results showed: 1) The first order equations were the most suitable forfitting the adsorption under various temperature levels with constant K+ concentration indisplacing fluid. With temperature increasing, the fitness of Elovich equation increased,while those of power equation and parabolic diffusion equation decreased; 2)the apparentadsorption rate constant ka and the product of ka multiplied by the apparent equilibriumadsorption qincreased when temperature increased, while the apparent equilibrium adsorptionqreduced; 3)temperature influenced hardly the reaction order, the order of concentrationand adsorpton site were always 1 under various temperatures, if they were taken intoaccount simultaneously, the adsorption should be a two-order reaction process; 4)theGibbs free energy change △G of potassium adsorption were negative, ranged from -4444.56to -2450.63Jmol-1,and increased with temperature increasing, while enthalpy change △H,entropy change △S, apparent adsorption activation Ea, adsorption activation energy E1and desorption activation energy E2 were temperature-independent; 5)the adsorption wasspontaneous process with heat releasing and entropy dropping, fluvo-aquic soil releasedmore heat than cinnamon soil.
