Abstract:This paper summarized the theoretical and pract ical development in soil science in China during last 50 years, discussed the theoretical basis, research core, key components, basic tasks, important driving forces and strategic targets for Chinese modern soil science, and put forward a theoretical frame for modern soil science development according to internationally developing trend in soil science.

Abstract:In an incubation experiment, dynamic change in amounts of soil organic matter (SOM), HA and FA were studied during corn stalk (CS) decomposition in dark-brown soil by δ¹³C method.The results showed that organic carbon from both new added CS and original soil decreased, but decomposition rate of the latter was slower than that of the former during incubation periods.The residual rate of CS was about 36% at 360th day and 24% at 720th day, whereas that of original SOM was above 90% at 360th day and about 76% at 720th day.In the initial stage of incubation (1hour), the formed rate of FA was faster than that of HA.Then, FA transformed into HA.After 15th day, HA transformed into FA again.HA and FA from original SOM also transformed each other, and it was still the same trend that FA transformed into HA before 15th day.But the transformed rate in original SOM was relatively slower than that in new-formed SOM.δ¹³C method can be used to study decomposition dynamics of SOM in short-term incubation experiment (several months~several years).

Abstract:Four subtropical soils/sediments include marine top sediment, river sediment, pond sediment, and paddy soil were collected, and soils/sediments organic matter (SOM) was extracted from the samples with chemical methods.Chemical characterization of SOM shows that soils/sediments organic matter is highly heterogeneous, includes humic acid, diagenetically kerogen, and black carbon.Structure analysis on these SOM reveal that humic acid and kerogen usually formed from organism under reducing conditions.However, Black carbon was produced from the incomplete combustion of fossil fuels and biomass, structurally rigid, physically condensed, and less polar than humic acid and kerogen.Systematic study of SOM heterogeneity will greatly help us to precisely understand the process of biogechemistry and organic pollutant behavior in natural system.

Abstract:Organic matter is an important soil component that influences the physical, chemical and biological properties of soils.Maintenance of its content in the soil has been the crucial measure for improving productivity and stabilizing ecosystems.Stabilization of the organic matter also plays a pivotal role in controlling global warming through an increasing sequestration of atmospheric CO₂ to the plant-soil system.In this paper, dynamics and processing mechanisms of soil organic matter accumulation for a cultivation chronosequence in paddy field were studied in subtropical China by sampling in field, and determining steady-state soil C contents.Under paddy cult ivation, soil organic C and N increased rapidly for 30 years, leveling off thereafter.After 30 years of rice planting with irrigation, 0~20 cm soil organic C and N increased to 20 g kg^-1 and 1.6 g kg^-1, respectively, and then insignificantly changed even through 80 years of utilization.During 20 days' incubation, the mineralization rates of 0~10 cm soil organic C and N in a cultivation chronosequence of paddy field ranged from 2.2%~3.3% and 2.8%~6.7%, which in general increased with soil organic C and N contents.Soil microbial biomass C increased proportionately with cultivation years, in comparison, the soil microbial biomass N increased in the first 30 years and then leveled off.0~10 cm soil cultivated as paddy field for 30 years has a 332.8 mg kg^-1 of microbial biomass C and 23.85 mg kg^-1 microbial biomass N, which were 111% and 47% higher than that for paddy field cultivated for 3 years.The numbers of bacteria in the soil cult ivated as paddy field for 30 years were 1.1-fold (0~10 cm) and 3.8-fold (10~20 cm) higher than that for 3 years, and the corresponding values in soils cultivated for 80 years were 19-fold (0~10 cm) and 12-fold (10~20 cm).The number of fungi was also increased in the first 30 years' cultivation and then leveled off.Furthermore, the increasing community of bacteria from 4 in wasteland to 8 in paddy soil under 30~80 years of cultivation indicated the improvement of soil fertility.

Abstract:Adsorption of acid phosphatase on yellow brown soil, latosol, kaolinite, goethite and δ-MnO₂ in a series of phosphate solutions different in concentration was investigated.Results showed that, with increase in phosphate concentration, isotherms of phosphatase adsorption on soil colloids and minerals were changing from L type (Langmuir) to C type (linear).The transformation of adsorpt ion isotherm was ascribed to competition between phosphate and enzyme molecules for adsorption sites on soil colloids and minerals.With the increase in phosphate in the system from 0 to 100 mmol L^-1, a sharp fall was observed for the amount of enzyme adsorbed.When the concentration came within the range of 100~500 mmol L^-1, no remarkable variation of the amount of enzyme adsorbed was observed.The inhibitory effect of phosphate on the adsorption of enzyme was dependent on the surface characteristics of soil colloids and minerals, especially the quant ity of hydroxyls, the concentrat ion of phosphate and the amount of enzyme added.The most effect was found in goethite and lateritic colloids which contain more ferri-aluminum hydroxide.

Abstract:Iron oxides in soils play very important roles as one of the acceptors of electrons transferred from reducing organic matters under submergence condit ion.Attempt had been made to simulate the reaction between reducing organic matters and iron oxides in soils in the study, in which vitamin C was used as the reducing organic matter and goethite synthesized in laboratory was also used.The result indicated that an increase in pH was observed in the process of reaction between vitamin C and goethite, due to the proton consumptions.It was suggested that the reaction between vitamin C and goethite was heterogeneous reaction and, it took rather longer time to reach an equilibrium.At the beginning of reaction, the change of Fe²⁺ in solution could not be observed, suggesting that the dissolution of Fe²⁺ from goethite was very slow.pH had effect on the reaction, the reaction rate decreased with an increase in pH.The reason for this phenomenon might be inferred from influence of pH on the amount of posit ive charges on the surface of goethite.

Abstract:Changes in fract ionation of copper, cadmium, lead, zinc and chromium in the rhizosphere of maize during a period of 100 days were investigated using rootmat box.It was shown that there were significant changes in all forms of copper and cadmium and some forms of zinc and lead.The changes varied in direction and magnitude during the experimental period.Uptake of plant remarkably influenced exchangeable copper and carbonate bound copper and zinc.

Abstract:The model of soil environmental geochemical baseline was built by application a normalization procedure.Based on the baseline model and the normalization procedure, the authors assessed heavy metal pollution in Panzhihua region.The results showed heavy metal pollution in Panzhihua region characterized as follow: a.Cd was uncontaminated; b.Co, Cr, Ni, Pb were slightly contaminated; c.As and Zn were slightly to moderately contaminated; d.heavy metal pollut ion mainly distributed in industrial and mining area.

Abstract:Through continuous bathe equilibrium experiments, the release of aluminum and dissolved organic matter (DOM), and mobility of heavy metals affected by simulated acid rain in contaminated acidic red soil and yellow red soil were studied.The results showed a decrease of pH and base saturation, and increase content of exchangeable acidity in both uncontaminated and contaminated red soil and yellow red soil within the pH decreasing of simulated acid rain, significantly.The content of exchangeable hydrogen is higher and exchangeable aluminum is lower in contaminated soils compared to uncontaminated soils.The release of aluminum was mainly affected by pH of simulated acid rain.At simulated acid rain pH of no less than 4.50, the release was almost the same in tested soils.At simulated acid rain pH of 3.50, the release was almost the same in red soil and different in yellow red soil, obviously.At simulated acid rain pH of 3.00, the release was improving significantly in tested soils.However, the release of aluminum was less in contaminated tested soils than in un-contaminated tested soils, and, at the same time, the mobility of available heavy metals in contaminated tested soils was increased significantly.The release of DOM increased in contaminated red soil and yellow red soil by simulated acid rain, and the complex of DOMmetal is useful for release and transport of available heavy metals.

Abstract:Arylsulfatase is a principle enzyme involved in soil sulphur cycle and is one of the potential indicators of soil quality.Arylsulfatase activity of twelve paddy soil profiles in Taihu region were investigated.The average arylsulfatase activity was p nitrophenol(PNP) 160 μg g^-1 soil h^-1.The highest activity for the plowing layer of these paddy soils was PNP 315 μg g^-1 soil h^-1 while the lowest was PNP 75 μg g^-1 soil h^-1.The enzyme activities for most soils were in the range of PNP 100~200 μg g^-1 soil h^-1.Arylsulfatase activity in the plowing layer of paddy soils was significantly correlated with soil organic carbon content (R²=0.533).Arylsulfatase activity increased with pH when pH was below 5.2, and decreased with pH when pH was higher than 5.2.Arylsulfatase activity dropped with increasing profile depth for all profiles except Meiyan soil profile where the activity in the plowpan layer was higher than that in the plowing layer.No enzyme activity was detected when the depth is over 60 cm.The distribution of arylsulfatase activity in these profiles could be grouped into four different patterns according to its decrease trend within soil profile.

Abstract:Successive extraction method was adopted to study the characteristics of chemical forms of Cd and Pb in alluvial meadow soil and meadow cinnamon soil in the plain of Hebei, and the relationship between the forms of Cd, Pb and factors affect ing it by pot experiment and field sampling.The results showed that Cd, Pb contents of exchangeable form increased and those of carbonate combined and residual forms decreased with the increase of pollution extent in field soils.Cd, Pb contents of exchangeable and carbonate combined forms increased and those of organic and residual forms decreased with the increase of Cd, Pb added concentration in pot soils.Most of Cd was present in the exchangeable form(the order is: EXC > CAB > OXI > ORG > RES), and the most amount of Pb was associated with the carbonate and Fe-Mn oxide combined forms in heavy metal highly polluted soils.In lowly polluted soils, the residual and organic forms of Cd increased significantly (the order is: RES > CAB > ORG > EXC> OXI), and most of Pb was present in Fe-Mn oxide combined and residual forms.The concentration and proportion of the exchangeable and Fe-Mn oxide combined forms in alluvial meadow soil were lower than in meadow cinnamon soil.The major factor which effect on the chemical forms of Cd, Pb in soils were pH and the organic content.

Abstract:Soil erosion and water loss are two serious problems threatening the ecosystem and preventing the development of agriculture in the semiarid and arid regions.Polyacrylamide(PAM) can significantly amend the properties of soil.PAM, with high vicosity, can effectively improve the surface structure of soil, enhance the stability of soil, increase water infiltration and reduce soil erosion.The objective of this paper, with experiments conducted with rainfall simulator, was to determine the relations between soil erosion and applications of PAM under conditions of different rainfall intensities and slopes.Experiments showed that the soils treated with PAM had better infiltration and stability properties.With cohering significantly with particles of soil at surface, forming bigger aggregates and halting the formation of crust, PAM can provide erosion control and benefit infiltration.

Abstract:The differences of main properties of the soils between islands and the of coast mainland in Eastern China were studied through eight typical profiles from Zhejiang, Jiangsu and Shandong provinces.The soils are derived from the acid parent rocks.The results showed that pH, BS%, Silt/Clay, SiO₂/Al₂O₃ and SiO₂/R₂O₃ in island soils were higher than those in the coast mainland soils, while Redness Rating(RR) and Clayization Ratio in island soils were lower than those in the coast mainland soils with the same latitude.The soils of islands are characterized by rebasification, which makes it great difference from the soils of mainland.The intensity of pedogenic processes is weaker in island than in mainland with the same latitude.

Abstract:By using ¹⁵N techniques, effects of urea and KNO₃ on processes of N₂O production in Hydragric pad dy soil and Gleyic paddy soil, collected from Wuxi and Yingtan, respectively, were invest igated under flooding condit ions at 25.In the Hydragric paddy soil, N₂ was a predominated product of denitrification process.Addition of KNO₃ stimulated DNRA process and hence N₂O product ion.In the Gleyic paddy soil, N₂O was produced from denitrification and aerobic denitrification processes with its product ion rate increasing with soil pH and nitrate concentration.It was observed in some treatments of both the soils that the ¹⁵N abundance of N₂O was larger than those of all the inorganic nitrogen, NH₄⁺, NO₃^-, and NO₂^-, implying that the processes for N₂O production would take place inside cells of microbes.

Abstract:Through field fixed location experiment and greenhouse incubation experiment, as well as a series of determinations of soil physical and chemical properties, the ameliorative effect and mechanism of three kinds of organic material on vertisol-the middle-low yield soil of Huaibei area have been explored.The results indicated that returning organic material to soil can increase soil porosity, reduce soil bulk density, improve soil perviousness and soil retention of water and fert ilizer, raise soil buffer capacity, supply multinutrients, and increase crops yields.The mechanism involved not only the reduction of shear stress of montmorillonite was reduced by humus, and restraint of its expansibility and shrinkage, but also supplying act ive organic colloid to form organo-mineral composite aggregate.In addition, organic acid can dissolve CaCO₃ in soil and release active Ca²⁺, which formed the bridge of composite aggregate, thereby, improved soil pedality etc.

Abstract:To aim the problem of nitrogen fertilizer overused to cause lower efficiency of fertilizer-N ut ilization and environment pollution, the field and lysimeter experiments under different amount of fertilizer-N applied were conducted in the Taihu lake area to seek the optimum nitrogen rate for a high productive ricewheat system and reducing nitrate leaching.The preliminary results showed fertilizer-N rate used increased with yield of rice & wheat.Optimum rates of fertilizer-N ranged from 225 to 270 and 180 to 225 N kg hm^-2 for rice and wheat in the two main paddy soils, respectively.With both high percentage of earbearing tiller and setting percentage, yields of rice & wheat were higher at optimum rate of fertilizer-N used than at other treatments.Nitrogen was leached away from field mainly in the form of NO₃^--N, not NH₄⁺-N, and it occurred in the season of growing wheat and the early stage of rice pouding and transplanting.Nitrate-N concentrations in the leachate increased gradually with the increasing of fertilizer-N applications.Which in the lysimeter leachate ranged from 5.4 to 21.3 mg L^-1 from the field receiving 225 kg hm^-2, with 60% leachate being over the standard of 10 mg L^-1 NO₃^--N standard and in groundwater ranged from 1.9 to 11.0 mg L^-1 from the fields receiving 270 to 315 N kg hm^-2, with 20% samples being nearly and 10% over the standard, respectively.Although NO₃^--N levels in groundwater from fertilized fields are usually well below the standard, cumulating of high NO₃^--N leachate will be a potential risk of water contamination in Taihu Lake area.

Abstract:This study investigated population distribution and community structure of microorganisms and related ecological factors in the root layer of 10-, 40-and 90-year old tea plants, respectively.The populations of soil eutrophic bacteria, fungi, actinomycetes and Bacillus were measured by the plate-count method.Soil acidity, organic carbon, total nitrogen and total soluble phenol of the soil increased with the age of tea plants.Populations of microbes in the tea root layer varied with the age of tea plants.Eutrophic bacteria and actinomycetes and total microbes appeared as larger colony-forming-unit in the root layer of 10-year old tea plant, as compared with those of 40-and 90-year old tea plants, which were close each other.The size of fungi in the root layer of 10-and 90-year old tea plants was similar but larger than those in the root layer of 40-year old tea plants.The quantity of Bacillus, in the root layer of 40-year old tea plants was greater than those in the 10-or 90-year old tea plant root layer, with the latter having similar values.Soil microbial biomass carbon in the tea plant root layer increased significantly with the age of tea plants.Simultaneously, a significant correlation was not observed between microbial biomass carbon and total colony-forming microorganisms measured by the plate-counting method.Each of the soil properties including organic carbon, total soluble phenol, total nitrogen and pH, had a significant or very significant correlation with microbial biomass carbon.

Abstract:A solution culture experiment was conducted by using ¹⁴C labeled methods to investigate the effect of boron on carbohydrate assimilation and transformation in wheat.The results showed that the soluble sugar content in stems was higher in the treatments of boron-free and 0.3 mol L^-1 B (B_0.3) than in the treatments of 1 and 10 mol L^-1 B (B₁ and B₁₀) because the abnormal developmental stamens caused an accumulation of soluble sugar in stems.However, the translocation of soluble sugar was not retarded in the treatments of boron-free and boron-deficiency.Boron-free affects the accumulation of total sugar in wheat, while boron-deficiency (B_0.3) affects the accumulat ion of total sugar in only in the productive growth stage, resulted in the failure of grain set and decrease in accumulation of total.

Abstract:Decomposition of hybrid elephant straw ¹⁴C in situ in the field was studied using the ¹⁴C-tracer technique in yellow-brown earth under a wheat-rice rotation system for one year.Results indicated that the amount of straw added had little effect on its decaying rate.After one year, straw ¹⁴C decomposed by about 72% with a decaying rate constant of 2.7×10^-3 d^-1.However, straw addition was closely related to decomposition of native soil C and balance of soil carbon.Soil native carbon decomposed by 5.45% ~ 6.07% annually with a decaying rate constant from 1.04×10^-4 d^-1 to 1.18×10^-4 d^-1.With straw addition, decomposition of straw ¹⁴C increased in both amount and rate, while the net loss of soil organic C decreased.Biomass ¹⁴C accounted for 3.79%~10.63% of input ¹⁴C and 12.27%~17.43% of soil residual ¹⁴C.Its variat ion was much significant than that of biomass ¹²C.The ratio of biomass ¹²C to biomass ¹⁴C varied from 0.74 to 3.85, which indicated that under most situations, native soil C was still the major source of energy and nutrients for microorganisms.Turnover rates of soil biomass ¹⁴C and ¹²C were 1.10~1.18 a^-1 and 0.97~1.06 a^-1 respectively.Straw addition could accelerate turnover of soil organisms, and in turn increase in the turnover rate of soil organisms accelerate the decaying rate of straw C and soil native C.Decomposition processes of soil native C and straw C showed similar trends to dynamics of soil biomass ¹²C and soil biomass ¹⁴C, which indicated that decomposition rates of organic C were the apparent indication of activity of soil organisms.

Abstract:Insufficient nutrient supply during later growth period in plastic mulched crops has been a big problem since top dressing is unpractical.The effects of different kinds of long-lasting urea (MUA1 and MUA2) and long-lasting ammonium bicarbonate (MAB) on plastic mulched winter wheat were compared with normal urea (UA) and normal ammonium bicarbonate (AB) applied as basal dressing all in one time in a field trial.As compared with UA, MUA1 and MUA2 were found to increase wheat grain yield by 10.5% and 12.4%, increase the nitrogen use efficiency (NUE) in grain by 10.1 and 10.9 percentage points, and the nitrogen productivity index (NPI) by 3.9 kg and 4.6 kg.MAB, the fertilizer effects of which was approximately equal to that of UA, was found to have an increase of grain yield by 6.6%, increase of NUE and NPI by 5.8 percentage points and 2.3 kg respectively compared with AB.Until two weeks before the harvest, MUA1, MUA2 and MAB kept the higher green-leaf index and the larger flag leaf area, increasing by 18.5%, 34.8%, 12.3%, and 25.9%, 34.5%, 42.90% respectively, which may contributed to the higher grain yield and nitrogen use efficiency.

Abstract:The authose used tea-polyphenol as inhibitor and studied its effects on the urease and some other enzymes in paddy soil derived from red soil, as well as the vitality of rice roots and the growth of rice.The results show that its inhibition to urease of the paddy soil derived from red soil was fairly strong, whereas the inhibition to protein enzyme, catalase and cellulase in the soil was relatively weak.The tea-polyphenol also had a comparatively faint inhibition to the vitality of rice roots and the growth of rice.Compared with hydroquinone, the tea-polyphenol's side effects of inhibition was weaker, hence it is a better inhibitor.

Abstract:There have been many papers reported on low use efficiency of chemical N fertilizer and its loss leading to environmental pollution but very few ones are found to have advanced achievements.High contents of nitrate in some plants, especially in vegetables and fruits, decrease significantly the qualities of these plants, thus becoming one of the limiting factors for the exporting of the products.Studies on the mechanisms and ways to high use efficiency of N in plant itself have become one of the issues in plant N nutrition in the last a few years.Vacuoles occupy about 90% of the total volume in matured cells of plants and the concentrations of nitrate in vacuoles and cytosol are normally 30~50 mol m^-3 and 3~5 mol m^-3, respectively.Therefore, it is one of the ways to increase the N use efficiency and decrease the contents of nitrate in plants that the nitrate in vacuoles are remobilized and reutilized.The present paper reviews the main studies on the behavior of nitrate in vacuoles.The author proposes in the first time that there should be some close relat ionships between the influx and efflux of nitrate though tonoplasts and N use efficiency in plants.The author also on purpose initiates the research work of this field in China by exposing some issues to be considered.

Abstract:对于含有粘粒的土壤,随着土壤含水量的改变,土壤容积也会随之改变,从而影响了容重—含水量的关系^[1]和土壤机械特性^[2],同时从土壤干湿变化可以预测田间地表收缩与膨胀、计算含水量剖面和制定灌溉计划^[3]。土壤在饱和—干燥收缩过程中容易产生表面下陷和裂隙,使得水分和溶质通过收缩裂隙优先运移到下层土壤和地下水中^[4,5],造成水分、养分的流失,甚至引起地下水污染,因此土壤干湿收缩特征已引起众多的关注。

Abstract:近20年来随着区域人口的增加、盐渍地的改良与综合治理,黄淮海冲积平原区农业集约化程度不断提高,但农业灾害的类型却从过去的以旱涝为主转向以旱为主,地下水位明显降低。因此,研究农业集约化程度和气候环境条件的变化对土壤质量演变的影响是该区农业持续发展面临的重要课题。