Abstract:The development of soil science was influenced mainly by chemistry and geo-science since the 19^th century. Physics and mathematics did not play the important role in soil science till the middle of the 20^th century, but they have initiated the digitalization and information revolution in the field of soil science. This revolution finds expression in the tendency of modularization, in the tendency of digitalization which appeared first in soil classification and cartography,in the tendency of intelligentization, of which the strong treatment ability of information technology is used to form various soil expert systems, in the tendency of precision in the research of soil science which is promoted by 3S and PA and in the tendency of networking for soil information. In the end, the methodology in the development of digitalization and information of soil science is also discussed in this article.

Abstract:According to mass balance model and the assumption that ceasium-137 in plowed soils shows a uniform distribution through the plow layer, a quantitative model was developed to relate the amount of caesium-137 loss from the cultivated soil profile to rate of soil erosion. The model shows the facts that the radioactive decay of ¹³⁷Cs, ¹³⁷Cs input fraction, the depth of, plowed layer and sampling year have a great influence upon cultivated soil loss from soil profile. The result of model proves that the relationship between the rate of soil loss and ¹³⁷Cs depletion is neither linear nor logarithmic.

Abstract:There are some types of the paleosols in the hilly regions of Beijing. The seven layers of the paleosols is embedded in the loess section of Xihulin, which located in the second terrace of qshuihe River. According to the character of configuration and microconfiguration, the paleosols may be divided into the brown earth, carbonate drab soil, drab soil and leached drab soil. The research of its geo-chemical characteristics of elements revealed that there are marked differences for contents of CaO, Na₂OAl₂O₃, Fe₂O₃, SiO₂ and etc, among the paleosols and between the paleosols and the genetic units, the similar conclusion is observed from the research of the soil magnetic character. By means of comparing with other loess section, paleomagnetic studies and spore-pollen analysis, age is ensured. The different types of paleosols are formed during varied geologic period and are largely attributable to bia-climatic conditions, therefore paleosols indicated that the bio-climate had undergone 14 times replacement from warm to cold in the region of Beijing, as well North China, from 500 thousand to 10 thousand ago.

Abstract:In the paper quantificational relationship between soil permeability of upland and soil erodibility in hilly red soil region of southern China was studied, by using simulated rainfall and Guelph Permeameter. Results showed that there were negative correlations between saturated permeability K_fs of 0-5cm top soil and erodibility factor K of soil derived from Quaternary red clay and red sandstone, and the quantificational relationship can be expressed as K≈a·K_fs^-b+c, where coefficients a, b and c were decided by soil properties.

Abstract:Decline of available P (Olsen-P) in red earth with time may be devided into two stages: fast and slow stages. The former stage can be described with a straight line equation, y=a+bx, the second stage with a curve equation, y=a+blogx,where y=available P still remained, and x=incubation periods (month). Available P decline has a significant correlation with the amount of active Al content in soils but not with the amounts of active Fe and exchangeable Al. Pot experiment with three different types of soils: acidic red earth, neutral paddy soil, and calcareous fluvo-aquic soil, using wheat and rye grass as test plant, showed that the yield decline with soil and P reaction periods and ceased at different time with different soils. For the neutral paddy soil, the decline in yield ceased after 8 months' incubation, for fluva-aquic soil, after 16 months, but for red earth the decline ceased after more than 28 months. This may be due to different in extent of the formation reactions of P chelate ring structure and diffusing into the deeper layer under the surface of R₂O₃ and calcite in the soils. In neutral paddy soil this two reactions were weaker and led to higher available P remained after incubation period, while in acidic red soil and calcareous fulvo-acquit soil they were much more stronger especially in red soil, and lasting longer time.

Abstract:Pot experiments were carried out on the ¹⁵N-lablled soil after winter wheat to study the changes of soil microbial biomass C,N and soil fixed ammonium during rice growth. The results showed that soil microbial biomass C increased with the rice growing and reached the highest at the harvesting stage. The soil microbial biomass N decreased a little bit at the beginning of experiment and then rose to the highest at the tillering stage, after which it decreased again with the increase of N absorption by rice. The content of soil fixed ammonium changed little during the rice growing.some of the ¹⁵N fixed by soil clay minerals exchanged with the soil mineral N, showing that the fixed ammonium in last crop was also effective to rice at the second cropping.

Abstract:By applying labeled urea into a loamy meadow brown soil,a pot experiment with spring wheat as test crop was carried out. The results showed that in comparison with applying urea alone and urea+hydroquinone(HQ),an application of dicyandiamide(DCD),and especially of its combination with HQ, gave a much higher recovery of soil urea ¹⁵N, among which organic ¹⁵N occupied a great portion.These two treatments played an active role in the conservation of urea-deleased NH₄⁺-¹⁵N in soil and in the decrease of the accumulation of urea-derived (NO₃^-+NO₂^-)-¹⁵N. They could markedly promote the mineralization-immobilization turnover of fertilizer ¹⁵N following the hydrolysis of applied urea Synergistic effects of HQ and DCD on the contents of fertilizer-¹⁵N and NH₄⁺-¹⁵N in soil as well as the mineralization of soil organic-¹⁵N will appear after the application of labeled urea.

Abstract:Several models (quadratic,square root, linear+plateau, quadratic+plateau) used for describing crop yield response to N fertilizer at winter-wheat and summer-corn rotation are compared. Data from four experiments which were conducted at Beijing and Henan province are used. All models fit the data equally well evaluated by using the R² statistic, but using linear+plateau model can reduce optimum N rate, increase economic profit of N fertilizer at the premise that crop yield don't reduce. Analyzing from environmental factor, linear+plateau model can maintain the balance of soil inorganic N, improve N fertilizer recovery, reduce crop straw N content and the emission of NOx by straw burning. So, linear+plateau model is the most suitable model in winterwheat and summer-corn rotation system in north of China.

Abstract:The changes of exchange alkalinity and exchange acidity in the two types of red soil with the presence of three neutral salt solutions was controlled automatically equipment. It was found that in studied quantitatively by pH the solution of Na₂SO₄ the exchange alkalinity appeared at low pH, while exchange acidity at high pH. The amount of exchange alkalinity of latosol is larger than that of red soil. The exchange neutrality point which was not influenced by the concentration of Na₂SO₄ was nearby pH4.6.Only the exchange acidity appeared in the solutions of NaClO₄ and KClO₄ in the range of pH measured. The amount of exchange acidity was found more in the red soil than that in the latosol. For the same soil colloid the amount of exchange acidity in KClO₄ solution was greater than that in the NaClO₄ solution. The peak value of exchange acidity was shown at pH 4.3 in the solution of KClO₄ and at pH 5.8 in the solution of NaClO₄ for the latosol colloid.A method of measuring the SO₄^2-—exchange alkalinity was constructed.

Abstract:Accumulation of rare earth elements(REEs) in corn after application of REE-fertilizer was studied by pot experiment and the dose-dependent accumulation of exogenous REEs in different parts of corn was reported. Ratio of La/REE in soil, REE-fertilizers, and different parts of corn was used as fingerprinting in accompany with quantitative information. We found that the exogenous REEs could be incorporated into corn root and stem. When the dose of REE-fertilizer increased, exogenous REEs become gradually dominant in plant root and stem. When doses of REEs increased, REE enrichment factor in corn root and stem increases. It indicates that the bioavailability of exogenous rare earth element should be significantly higher than that in soil matrix. Incorporation of exogenous REE into corn leaf was found by fingerprinting analysis, but no significant accumulation of REEs in corn leaf was found even at high dosage.

Abstract:The 23 soil samples including the 6 types of managed soils were collected different regions in Shanxi Province for this research project The change of nitrate nitrogen accumulation with time was detemvned during the process of nitrification. The equation, dN/dt=bN(B-N)/B(N is the amount of NO₃^-N accumulation, t is time of incubation, and B is the asymptotic value of NO₃^-N, depending on the amount of NH₄-N added to the soil), was used to represent the accumulation of nitrate nitrogen with time. The maximal rate of nitrification (K_mx) and the delayed period (t_d) were derived from the equation and used to characterize quantitatively the nitrification process in various soil samples. The K_mx and t_d of surface soil samples were from 2.7 to 16.58 mg/kg·d and from 1.3-3.5d, respectively. The K_mx decreased and t_d increased with soil depth. Some soil properties affected the rate parameters.

Abstract:By using the method of pot culture experiment in the case of artificial climate the result indicated that the effects of light intensity(X₁)and N application(X₂) on lettuce yield(y)were mathematically represented by the following equation in this study: y=-0.375+0.0230X₁+9.421X₂+0.0251X₁X₂-0.131×10^-4X₁²-17.794X₂²;The efficiency of N fertilizer was influenced by light intensity. A quadratic multinomial equation y=b₀+b₁X + b₂X₂, could be used to describe the correlation between N application and lettuce yield. Also, quadratic or cubic multinomial equation could be used to describe the correlation between light and lettuce yield. Accordingly, the effects of light intensity(X₁)on N application (X₂) were mathematically represented by the following equation: X₂=0.446-0.477×10^-2X₁+0.269×10^-4X₁²-0.394×10^-7X₁³. Moreover, nitrogen nutrition of lettuce was bigger influenced by light and N application.

Abstract:Effect of water movement by soil potential under different temperature was studied. The results showed that unsaturated water transmitting rate was rising with the increasing of soil potential in case that temperature was constant, the rising value in cultivated loessial soil was larger than that in lou soil, and was rising with temperature rising in case that soil water content was constant, the value of temperature effect of unsaturated water transmitting rate (dk/dt) in lou soil was larger than that in cultivated loessial soil. Water transmitting rate of unsaturated soil also increased with the increasing of relative partial molal free energy variation,[Δ(ΔG)], and relative partial molal enthalpy variation,[Δ(ΔH)],in case that soil water content was constant. The increasing of water transmetting rate in cultivated loessial soil was larger than that in lou soil. The equations were regressed between [Δ(ΔG)] and [Δ(ΔH)] and k, they had better suitable.

Abstract:Solution culture experiments were conducted using the Zn-inefficient cultivar IR26 and the Zn-efficient cultivar IR8192-31-2 to study on physiological and biochemical mechanisms of rice plant adaptation to Zn deficiency with relation to bicarbonate tolerance. The results showed Bicarbonate strongly inhibited root growth of Zn-inefficient cultivar especially at low Zn concentration. In contrast, it had little effect on the root growth of Zn-fficient culrivar. Bicarbonate increased the concentrations of malate and citrate in the roots of both cultivars, but to greater extent for the Zn-inefficient than for the Zn-efficient cultivars. The results implied that the inhibitory effect of bicarbonate on root growth of the Zn-inefficient cultivar might result from high accumulation of organic acids in the root cells. PEP-case is a key enzyme for the synthesis of organic acid, so it was concluded that increase of organic acid by bicarbonate resulted from increase of PEP-case activity.

Abstract:Abies fabri forest is one of representative type of subalpine dark coniferous forest in Southwest China. The difference was obvious among CO₂ emissions from soils in Abies fabri forest region on the east slope of Gongga Mountain. The soil respiration of clearcut site approached 5.89 μmol/hm²s CO₂. The series of soil respiration was arranged: September>August>June>July>May>October>November. The soil respiration of Abies fabri forest approached 5.76μmol/hm²s CO₂. The series of soil respiration was arranged: August>July>September>June>May>October> November. The soil respiration of succession forest approached 3.26, mol/hm²s CO₂. The series of soil respiration was arranged: May>July> August>June> September>October>November. There existed a good linear correlation between soil respiration of cleareut site-succession forests and near surface-surface temperature. There existed a good linear correlation between soil respiration of Abies fabri forest and 5cm-10cm soil temperature. The soil CO₂ flux of clearcut site was 223.91kg/hm²d. The soil CO₂ flux of succession forest was 123.76kg/hm²d. The soil CO₂ flux of Abies fabri forest was 218.48kg/hm²d.

Abstract:The interactions between Pseudomonas Jluorescens X16L2 and Arbuscular Mycorrhizal Fungi (AMF) Glomus mosseae in the rhizosphere of wheat planted in the rhizobox and plastic box are studied by techniques of luminescent enzyme gene marker system, detecting of luminescence intensity and Succinate Dehydrogenase byeing. Because there is an inhibitory effect of Glomus mosseae on population density and physiological activity of Pf.X16L2, the mycorrhizosphere effect on Pf.X16L2 are lowered.Pf.X16L2 can promote the mycorrhizal infective ratio of Gl.mosseae on wheat roots but drops the Succinate Dehydrogenase activity of AMF mycelia. They can promote the growth of wheat during the middle and later growth stages.

Abstract:A new experiment method for determining parameters of soil water movement is put forward, which is that two parameters are determined in the same one experiment According to the principle of detemvning undisturbed soil sample parameters, a new device is designed and introduced. Through successive correction of the assumed soil water characteristic curve by iteration method, unsaturated hydraulic conductivity of the undisturbed soil sample is obtained. At the same time, the soil water characteristic curve of the soil sample is also obtained.

Abstract:离子交换树脂在农业上的应用已有近50年的历史,早期的研究主要集中在用阴离子交换树脂提取土壤中的磷;然后用阳离子交换树脂研究了土壤中钾的有效性及缓效钾的释放,后来开始用离子交换树脂测定土壤中营养元素。离子交换树脂在测定土壤养分的研究方面经历了树脂颗粒、树脂袋和树脂膜三个阶段。

Abstract:污水中含有益于作物生长的氮磷和微量元素,故污水土地处理会给作物产量和质量带来好处^[1],但使用的水力负荷率、污染负荷率(即投配水量)过高的话,会引起氮磷等元素迁移,对水环境产生二次污染。在过去同类研究中虽有许多关于土壤除氮效果的报导^[2～4],但绝大多数报导仅限于整个处理系统的去除效果上,很难查寻到有关污水中氮素在不同土壤和土层中氮素迁移的特征,因而影响土地处理场排水暗管设计的性能和采取有效调控方法提高土壤脱氮能力。本文通过对作物型污水土地处理实际运行过程氮的时空分布监测,深入了解水作条件下土壤不同形态氮素迁移特征,为进一步改进污水土地处理设计和提高处理系统的脱氮效果提供基础数据和科学依据。