A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning Sys...A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning System) and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of Landsat 5 Thematic Mapper (TM) images of bands 3, 4 and 5 obtained on December 15, 1992, and January 17, 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field check.Results showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grass land decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.展开更多
A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and ...A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.展开更多
A pot experiment was conducted to determine the dynamics of soil microbial biomass in a rainfed soil under wheat cultivation at the University of Arid Agriculture, Rawalpindi, Pakistan. The treatments applied were: 1)...A pot experiment was conducted to determine the dynamics of soil microbial biomass in a rainfed soil under wheat cultivation at the University of Arid Agriculture, Rawalpindi, Pakistan. The treatments applied were: 1) a control (CK), 2) NPK (0.44-0.26-0.18 g pot-1), 3) farmyard manure (FYM, 110 g pot-1), 4)poultry manure (PM, 110 g pot-1), 5) FYM (110 g pot-1) + NPK (0.44-0.26-0.18 g pot-1), 6) poultry manure (PM, 110 g pot-1) + NPK (0.44-0.26-0.18 g pot-1), 7) FYM (110 g pot-1) + NPK(S) (0.44-0.26-0.18 g pot-1, one half of the NPK at sowing and the other half one month after sowing), and 8) PM (110 g pot-1) + NPK(S) (0.44-0.26-0.18 g pot-1, one half of the NPK applied at sowing and the other half one month after sowing). The experiment was laid out using a completely randomized design with three replications. Microbial biomass C, N and P contents increased continuously from the beginning of the experiment up to the three-leaf stage. A slight decline was observed at the tillering stage in all treatments except with the organic manures + NPK(S) treatments. After tillering there was an increase in all treatments to the recorded maximum point at the full heading stage in all treatments except with the organic manures + NPK(S) treatments. In the FYM + NPK(S) and PM + NPK(S) treatments; however, there was a continuous increase in microbial biomass up to the heading stage. At the harvesting stage a sharp decline was noted in all treatments. The C:N ratio of microbial biomass in tested soil ranged from 7.8 to 11.3, while C:P ratio of microbial biomass in the tested soil ranged from 22.6 to 35.1 throughout all growth stages of the wheat crop.展开更多
A field experiment was conducted at the G.B. Pant University Research Station, Ujhani (U.P.) in rainy (Kharif) season of the year 1994-1995 to study the effect of Rhizobium, VAM (vesicular arbuscular myc- orrhiza) and...A field experiment was conducted at the G.B. Pant University Research Station, Ujhani (U.P.) in rainy (Kharif) season of the year 1994-1995 to study the effect of Rhizobium, VAM (vesicular arbuscular myc- orrhiza) and PSB (phosphate solubilizing bacteria) inoculation, with and without P, on blackgram (Vigna mungo L.) seed yield. Phosphorus application in soil with medium P content (5.4 mg kg～1) increased nodu- lation, grain yield, N and P in plant and grain over no phosphorus control. Forty kilograms of P-2O-5 each hactare recorded an increase of 20.6 % in nodule dry weight, significant increases of 0.35 g kg～(-1) in N con- centration and 1.28 g kg～(-1) in P concentration of plant over 20 kg P-2O-5 ha～(-1). Similar significant increases of 0.59 g kg～(-l) in grain yield and 0.54 and 0.23 g kg～(-1) in N and P concentrations of the grain, respectively, over 20 kg P-2O-5 ha～(-1) were also obtained with higher dose. Inoculation of Rhizobium ＋ VAM ＋ PSB at all the stages of plant growth recorded maximum increases in all the parameters studied. Dual inoculation of Rhizobium with either VAM or PSB was generally significant in the effect and better than that of VAM ＋ PSB, however, P accumulation in plant and grain was more with VAM ＋ PSB. Among single inocula tions, Rhizobium gave highest and 21.0 % more nodule number, 34.7 % more nodule dry mass, 0.73 g kg～(-1) more N in grain and 4.2 % higher grain yield over PSB. PSB, however, registered significant increases in P concentration in plant and grain over VAM and Rhizobium.展开更多
Monoammonium phosphate (1 mol L-1), monopotassium phosphate (1 mol L-1) and aluminum ohloride (5×10-3 mol L-1) were used to investigate the influence of pH on the formation of NH4-taranakite and K-taranakite in s...Monoammonium phosphate (1 mol L-1), monopotassium phosphate (1 mol L-1) and aluminum ohloride (5×10-3 mol L-1) were used to investigate the influence of pH on the formation of NH4-taranakite and K-taranakite in systems with a high NH4H2PO4 or KH2PO4 concentration. The experimental data indicated that the reaction products of aluminum with NH4H2PO4 or KH2PO4 changed with the pH in the systems. In a pH range of 2.5 to 10.0, as the pH increased, the products in either ammonium or potassium system followed the sequence: taranakite, amorphous (NH4, K)2AlH(PO4)2 .4H2O, and then crystalline (NH4, K)AlPO4OH.2H2O. However, the pH ranges of the formation of these products in ammonium system were different from potassium system. NH4-taranakite formed from pH 2.75 to PH 5.75, whereas K-taranakite formed in the pH range of 3.00 to 5.00. From the theoretical calculation by a computer program (GEOCHEM version 2.0), NH4-taranakite and K-taranakite could form at the pH from 1.50 to 8.30 and from 1.25 to 8.45,respectively. These pH ranges were much wider than the experimental results. The difference between the experimental data and theoretical data was attributed to the lack of kinetic data and/or the incompleteness and inaccuracy of the thermodynamic data in the data base of the program. The PH ranges of the formation of the taranakites indicated that the taranakites could exist in the immediate vicinity of phosphate fertilizer zone as reaction products of phosphate fertilizers with soils, especially acidic soils, resulting in the fixation of not only phosphate but also nitrogen and/or potassium in soils.展开更多
Four testing methods using cation exchange membrane (CEM),ammonium acetate,ASI(0.25mol L^-1 NaHCO3+0.01mol L^-1 EDTA +0.01 molL^-1 NH4F) and 1.0molL^-1 boiling nitric acid,respectively,were used to evaluate soil avail...Four testing methods using cation exchange membrane (CEM),ammonium acetate,ASI(0.25mol L^-1 NaHCO3+0.01mol L^-1 EDTA +0.01 molL^-1 NH4F) and 1.0molL^-1 boiling nitric acid,respectively,were used to evaluate soil available K.The soil K tested by CEM was significantly correlated with that by the other (conventional)methods(r^2=0.43^**-0.95^***).The soil K tested by CEM saturated with NH4HCO3(15min extraction)was most closely correlated with that by the other methods(r^2=0.60^**-0.95^***),Potassium availability,as predicted by soil test,was comparable to actual K uptake by canola and wheat grown on the soils in growth chamber.Regression analyses showed that plant K uptake was more closely correlated wiht K extracted by CEM(r^2=0.56^**-0.81^***)than that by the conventional methods(r^2=0.46^***-0.81^***),most colsely correlated with that by NH4HCO3-saturated CEM for 15 min (r^2=0.81^***).and worst correlated with that by HNO3(r^2=0.45^**-0.72^***)展开更多
Limited information is available concerning the mineralogy of paddy soils in the southeastern China.Using chemical methods in conjunction with X-ray diffractometry, we studied the mineral composition of three paddy so...Limited information is available concerning the mineralogy of paddy soils in the southeastern China.Using chemical methods in conjunction with X-ray diffractometry, we studied the mineral composition of three paddy soils: Jinghua (paddy soil on Quaternary red clay), Fuyang (Hapl-percogenic loamy paddy soil), and Shaoxing (gleyic clayey paddy soil). All the soils contained quartz, mica, vermiculite, chlorite and kaolinite, and the distribution of these minerals varied with soil particle size fractions. The clay fraction of the F’uyang and Shaoxing soils also contained smectite. Although X-ray data did not show the presence of smectite in the Jinghua soil, this mineral was identified by the chemical method, suggesting a transitional property of the mineral in the soil. Hydroxy-Al interlayered minerals were also present in the clay fraction.The amount of smectite in the soils was 31.6 (Shaoxing), 16.5 (Fuyang), and 21.4 (Jinghua) g kg-1; for vermiculite it was 33.3 (Shaoxing), 16.5 (Fuyang), and 8.5 (Jinghua) g kg-1. Smectite was only found in the clay fraction. In contrast, amounts of vermiculite in soil particle size fractions were 3.0～11.4 (sand),2.1～6.0 (coarse silt), 4.6～18.9 (medium silt), 0.9～40.0 (fine silt), and 17.0～108 (clay) g kg-1. The amount of noncrystalline aluminosilicates in the soils in g kg-1 decreased in the order: Shaoxing (2.4) > Jinghua (1.9) > Fuyang (1.7). This study has provided useful mineralogical information that is fundamental in future developmellt of management strategies of the soils.展开更多
The influence of soil chemical properties and soil nutrition on cotton yields was studied by means of establishing mathematical models.The nultivarate quadratic regression equations developed by a stepwise regression ...The influence of soil chemical properties and soil nutrition on cotton yields was studied by means of establishing mathematical models.The nultivarate quadratic regression equations developed by a stepwise regression method not only presented the single effect of soil factors but also displayed the interaction(synergistic or antagonistic) of soil nutrients.The effect of individual factor and the way of nutrient interaction were further analysed by the path analysis method.The results showed that among major factors affecting cotton yields,there existed the interactions between macronutrients(available P× available K),and between macronutrients and microelements(N×Zn,P×Mo,P×Cu,P×Zn,K×Mo)besides the single effect of soil pH,total P ,available Cu and available Zn.展开更多
The effects of three electrolyte anions,ionic strength and pH on the adsorption of sulfate by two variable charge soils,with different surface charge properties were studied.Under the conditions of the same pH and ion...The effects of three electrolyte anions,ionic strength and pH on the adsorption of sulfate by two variable charge soils,with different surface charge properties were studied.Under the conditions of the same pH and ionic strength the effect of electrolyte anions on the adsorption of sulfate was in the order of Cl^->NO3^->ClO4^-,indicating the difference of the nature among these three anions.For ferralsol in the same concentration of chloride and perchloride solutions,the two sulfate adsorption-pH curves could intersect at certain pH value.When pH was higher than the intersecting point.more sulfate was adsorbed in the perchloride solution,while when it was lower than the intersecting point,more sulfate was adsorbed in the chloride solution.In different concentratioins of electrolyte solution,the curves of the amount of oxy-acid anion adsorbed,which changed with pH,could intersect at a certain pH,which is termed point of zero salt effect(PZSE) on adsortpion.The nature of electrolyte anions influenced obviously the appearace of PZSE for sulfate adsorption.For ferralsol the curves of adsorption converged to about pH 7 in NaCl solution seemed to intersect in NaNO3 solution and to have a typical PZSE for sulfate adsorption in NaClO4 solution,For Acrisol the three curves of adsorption were nearly parallel in NaCl and NaNO3 solutions and converged to pH 6.5 in NaClO4 solution.展开更多
Field and greenhouse studies were conducted in Prince Edward Island (P.E.I.) on soybean (Glycine max(L.) Merr.), red clover (Trifolium pratense L.),alfalfa (Medicago sativa L.), and rutabaga (Brassica napobrassica,Mil...Field and greenhouse studies were conducted in Prince Edward Island (P.E.I.) on soybean (Glycine max(L.) Merr.), red clover (Trifolium pratense L.),alfalfa (Medicago sativa L.), and rutabaga (Brassica napobrassica,Mill).Plant B concentrations were compared to soil B extracted by hot-water,0.05 M HC1,1.5 M CH3COOH and 0.01 M CaCl2.The r values for extractable soil B vs.plant B were:hot water (0.67),0.05 M HCl(0.82),1.5M CH3COOH(0.78) and hot 0.01 M CaCl2(0.61).Results of soil B from the 0.05 M HCl extracts were generally found to give the best correlation and linear regression among the four extractants tested for predicting the availability of B to the plants.Overall,the 0.05 M HCl proved to be superior to hot water extraction and is recommended for predicting the available B status of the acid soils of P.E.I.The probability of error with 0.05 M HCL is less since it is shaken for a fixed period of time as opposed to subjective error which could be caused in monitoring the boiling time using hot water.展开更多
基金Project supported by the Tingthanathikul Foundation of Thailand, the Provincial Natural Science Foun- dation of Jiangxi (No. 0230025) the Open Research Foundation of Hubei Provincial Key Labaratory of Waterlogged Disaster and Wetland Agriculture (No. H
文摘A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning System) and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of Landsat 5 Thematic Mapper (TM) images of bands 3, 4 and 5 obtained on December 15, 1992, and January 17, 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field check.Results showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grass land decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.
基金Project supported by the Chinese Postdoctoral Foundation (No. 10129) and the Swedish Agricultural Science Research Foundation (N
文摘A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.
文摘A pot experiment was conducted to determine the dynamics of soil microbial biomass in a rainfed soil under wheat cultivation at the University of Arid Agriculture, Rawalpindi, Pakistan. The treatments applied were: 1) a control (CK), 2) NPK (0.44-0.26-0.18 g pot-1), 3) farmyard manure (FYM, 110 g pot-1), 4)poultry manure (PM, 110 g pot-1), 5) FYM (110 g pot-1) + NPK (0.44-0.26-0.18 g pot-1), 6) poultry manure (PM, 110 g pot-1) + NPK (0.44-0.26-0.18 g pot-1), 7) FYM (110 g pot-1) + NPK(S) (0.44-0.26-0.18 g pot-1, one half of the NPK at sowing and the other half one month after sowing), and 8) PM (110 g pot-1) + NPK(S) (0.44-0.26-0.18 g pot-1, one half of the NPK applied at sowing and the other half one month after sowing). The experiment was laid out using a completely randomized design with three replications. Microbial biomass C, N and P contents increased continuously from the beginning of the experiment up to the three-leaf stage. A slight decline was observed at the tillering stage in all treatments except with the organic manures + NPK(S) treatments. After tillering there was an increase in all treatments to the recorded maximum point at the full heading stage in all treatments except with the organic manures + NPK(S) treatments. In the FYM + NPK(S) and PM + NPK(S) treatments; however, there was a continuous increase in microbial biomass up to the heading stage. At the harvesting stage a sharp decline was noted in all treatments. The C:N ratio of microbial biomass in tested soil ranged from 7.8 to 11.3, while C:P ratio of microbial biomass in the tested soil ranged from 22.6 to 35.1 throughout all growth stages of the wheat crop.
基金Project supported by the G. B. Pant Univ. of Agri. and Tech., Pantnagar, India.
文摘A field experiment was conducted at the G.B. Pant University Research Station, Ujhani (U.P.) in rainy (Kharif) season of the year 1994-1995 to study the effect of Rhizobium, VAM (vesicular arbuscular myc- orrhiza) and PSB (phosphate solubilizing bacteria) inoculation, with and without P, on blackgram (Vigna mungo L.) seed yield. Phosphorus application in soil with medium P content (5.4 mg kg～1) increased nodu- lation, grain yield, N and P in plant and grain over no phosphorus control. Forty kilograms of P-2O-5 each hactare recorded an increase of 20.6 % in nodule dry weight, significant increases of 0.35 g kg～(-1) in N con- centration and 1.28 g kg～(-1) in P concentration of plant over 20 kg P-2O-5 ha～(-1). Similar significant increases of 0.59 g kg～(-l) in grain yield and 0.54 and 0.23 g kg～(-1) in N and P concentrations of the grain, respectively, over 20 kg P-2O-5 ha～(-1) were also obtained with higher dose. Inoculation of Rhizobium ＋ VAM ＋ PSB at all the stages of plant growth recorded maximum increases in all the parameters studied. Dual inoculation of Rhizobium with either VAM or PSB was generally significant in the effect and better than that of VAM ＋ PSB, however, P accumulation in plant and grain was more with VAM ＋ PSB. Among single inocula tions, Rhizobium gave highest and 21.0 % more nodule number, 34.7 % more nodule dry mass, 0.73 g kg～(-1) more N in grain and 4.2 % higher grain yield over PSB. PSB, however, registered significant increases in P concentration in plant and grain over VAM and Rhizobium.
文摘Monoammonium phosphate (1 mol L-1), monopotassium phosphate (1 mol L-1) and aluminum ohloride (5×10-3 mol L-1) were used to investigate the influence of pH on the formation of NH4-taranakite and K-taranakite in systems with a high NH4H2PO4 or KH2PO4 concentration. The experimental data indicated that the reaction products of aluminum with NH4H2PO4 or KH2PO4 changed with the pH in the systems. In a pH range of 2.5 to 10.0, as the pH increased, the products in either ammonium or potassium system followed the sequence: taranakite, amorphous (NH4, K)2AlH(PO4)2 .4H2O, and then crystalline (NH4, K)AlPO4OH.2H2O. However, the pH ranges of the formation of these products in ammonium system were different from potassium system. NH4-taranakite formed from pH 2.75 to PH 5.75, whereas K-taranakite formed in the pH range of 3.00 to 5.00. From the theoretical calculation by a computer program (GEOCHEM version 2.0), NH4-taranakite and K-taranakite could form at the pH from 1.50 to 8.30 and from 1.25 to 8.45,respectively. These pH ranges were much wider than the experimental results. The difference between the experimental data and theoretical data was attributed to the lack of kinetic data and/or the incompleteness and inaccuracy of the thermodynamic data in the data base of the program. The PH ranges of the formation of the taranakites indicated that the taranakites could exist in the immediate vicinity of phosphate fertilizer zone as reaction products of phosphate fertilizers with soils, especially acidic soils, resulting in the fixation of not only phosphate but also nitrogen and/or potassium in soils.
文摘Four testing methods using cation exchange membrane (CEM),ammonium acetate,ASI(0.25mol L^-1 NaHCO3+0.01mol L^-1 EDTA +0.01 molL^-1 NH4F) and 1.0molL^-1 boiling nitric acid,respectively,were used to evaluate soil available K.The soil K tested by CEM was significantly correlated with that by the other (conventional)methods(r^2=0.43^**-0.95^***).The soil K tested by CEM saturated with NH4HCO3(15min extraction)was most closely correlated with that by the other methods(r^2=0.60^**-0.95^***),Potassium availability,as predicted by soil test,was comparable to actual K uptake by canola and wheat grown on the soils in growth chamber.Regression analyses showed that plant K uptake was more closely correlated wiht K extracted by CEM(r^2=0.56^**-0.81^***)than that by the conventional methods(r^2=0.46^***-0.81^***),most colsely correlated with that by NH4HCO3-saturated CEM for 15 min (r^2=0.81^***).and worst correlated with that by HNO3(r^2=0.45^**-0.72^***)
文摘Limited information is available concerning the mineralogy of paddy soils in the southeastern China.Using chemical methods in conjunction with X-ray diffractometry, we studied the mineral composition of three paddy soils: Jinghua (paddy soil on Quaternary red clay), Fuyang (Hapl-percogenic loamy paddy soil), and Shaoxing (gleyic clayey paddy soil). All the soils contained quartz, mica, vermiculite, chlorite and kaolinite, and the distribution of these minerals varied with soil particle size fractions. The clay fraction of the F’uyang and Shaoxing soils also contained smectite. Although X-ray data did not show the presence of smectite in the Jinghua soil, this mineral was identified by the chemical method, suggesting a transitional property of the mineral in the soil. Hydroxy-Al interlayered minerals were also present in the clay fraction.The amount of smectite in the soils was 31.6 (Shaoxing), 16.5 (Fuyang), and 21.4 (Jinghua) g kg-1; for vermiculite it was 33.3 (Shaoxing), 16.5 (Fuyang), and 8.5 (Jinghua) g kg-1. Smectite was only found in the clay fraction. In contrast, amounts of vermiculite in soil particle size fractions were 3.0～11.4 (sand),2.1～6.0 (coarse silt), 4.6～18.9 (medium silt), 0.9～40.0 (fine silt), and 17.0～108 (clay) g kg-1. The amount of noncrystalline aluminosilicates in the soils in g kg-1 decreased in the order: Shaoxing (2.4) > Jinghua (1.9) > Fuyang (1.7). This study has provided useful mineralogical information that is fundamental in future developmellt of management strategies of the soils.
文摘The influence of soil chemical properties and soil nutrition on cotton yields was studied by means of establishing mathematical models.The nultivarate quadratic regression equations developed by a stepwise regression method not only presented the single effect of soil factors but also displayed the interaction(synergistic or antagonistic) of soil nutrients.The effect of individual factor and the way of nutrient interaction were further analysed by the path analysis method.The results showed that among major factors affecting cotton yields,there existed the interactions between macronutrients(available P× available K),and between macronutrients and microelements(N×Zn,P×Mo,P×Cu,P×Zn,K×Mo)besides the single effect of soil pH,total P ,available Cu and available Zn.
文摘The effects of three electrolyte anions,ionic strength and pH on the adsorption of sulfate by two variable charge soils,with different surface charge properties were studied.Under the conditions of the same pH and ionic strength the effect of electrolyte anions on the adsorption of sulfate was in the order of Cl^->NO3^->ClO4^-,indicating the difference of the nature among these three anions.For ferralsol in the same concentration of chloride and perchloride solutions,the two sulfate adsorption-pH curves could intersect at certain pH value.When pH was higher than the intersecting point.more sulfate was adsorbed in the perchloride solution,while when it was lower than the intersecting point,more sulfate was adsorbed in the chloride solution.In different concentratioins of electrolyte solution,the curves of the amount of oxy-acid anion adsorbed,which changed with pH,could intersect at a certain pH,which is termed point of zero salt effect(PZSE) on adsortpion.The nature of electrolyte anions influenced obviously the appearace of PZSE for sulfate adsorption.For ferralsol the curves of adsorption converged to about pH 7 in NaCl solution seemed to intersect in NaNO3 solution and to have a typical PZSE for sulfate adsorption in NaClO4 solution,For Acrisol the three curves of adsorption were nearly parallel in NaCl and NaNO3 solutions and converged to pH 6.5 in NaClO4 solution.
文摘Field and greenhouse studies were conducted in Prince Edward Island (P.E.I.) on soybean (Glycine max(L.) Merr.), red clover (Trifolium pratense L.),alfalfa (Medicago sativa L.), and rutabaga (Brassica napobrassica,Mill).Plant B concentrations were compared to soil B extracted by hot-water,0.05 M HC1,1.5 M CH3COOH and 0.01 M CaCl2.The r values for extractable soil B vs.plant B were:hot water (0.67),0.05 M HCl(0.82),1.5M CH3COOH(0.78) and hot 0.01 M CaCl2(0.61).Results of soil B from the 0.05 M HCl extracts were generally found to give the best correlation and linear regression among the four extractants tested for predicting the availability of B to the plants.Overall,the 0.05 M HCl proved to be superior to hot water extraction and is recommended for predicting the available B status of the acid soils of P.E.I.The probability of error with 0.05 M HCL is less since it is shaken for a fixed period of time as opposed to subjective error which could be caused in monitoring the boiling time using hot water.
