Abstract:Fifteen soil samples were collected from Zhejiang and Jiangsu provinces to study the mechanism of phosphate sorption by soils in relation to the kinds of canon of supporting electrolyte and the change of soil pH values through equilibrium.Increasing the pH of strong acidic soil by adding base resulted in the,hydrolysis of exchangeable Al and formation of polymeric hydroxy-Al species which increased the sorption of added P,The reaction of phosphate with acidic soil might promote the hydrolysis of exchangeable Aland release lmoton,and result in drop in the pH of the system.There might be calcium phosphates formation in soils with P addition n 0.01 mol CaCl₂ when pH>6,causing the equilibriatrn concentration of P to decrease markedly.Organic matter had an important effect on P sorption by soils.At iow pH,organic matter might inhibit the hydyolysis of Al⁸⁺ in solution through Al-organci complex formation.Mceanwhile,the organci anions might compete with phosphate for reaction sires on the surface of hydroxy-Al species.Both of the mechanisms meantioned above leaded to the decrease of P sorption in a cidic soils.

Abstract:Experimental data showed that the addition of rice straw,pig manure,and milk vetch could increase the resin-P but decrease the P adsorption of soils with different properities.The former was ettri3uted to the dis solution and complexing effect of organic acids prnduced when incubation of organic manure with s oils,and,the later was believed to he due to some phosphorus adsorbing sites of soil masked by the carbohydrates in organic manure.This assumption was supported by the data that the removal of soil organic matter increased the P adsorption of soil and water soluble organic matter extracted from organic manures has the ability to compete with phosphate for adsorption of soil.

Abstract:The desorption of phosphate determines the transformation and translocation of phosphorus in soils,and affects the P nutrition of soils and the environmental effect of phosphorus.Accordingly,it is of great importance to study the desorption characteristics of phosphate.In she present study laterite (L),volcanic ash soil (V),kaolinite (K1) and synthetic amorphous aluminum silicate (A_Al-si),amorphous iron oxide (A_Fe)and gibbsite (G) were used to investigate the desorption characteristics of phosphate on the variable-charge surface in soils.The results showed that the phosphate desorbed by 0.01 mo1L^-1 NaF (pH 9.08) was determined by phosphate adsorbed previously,and the relationship between them could be well described by using linear and exponential equations.The average desorption percentages were shown as follows: Kl(66%)>A_Al-si;(60%)>L(55%);A_Fe(29%)>G(23%)>>V(9%).The variatton degree of desorption percentage was related to the constituents of samples.The phosphate desorption was determined by the pH of desorption solution which could affect the proton dissociation of phosphate and the surface charges of colloids.The phosphate desorption increased consistently with the initial pH(pHi) of desorbent except that for the kaolinite and gibbsite it decreased at first and then increased.The p1H of equilibrium desorption solution (pHe) firstly showed an to crease and then followed by a decrease.When the ΔpH,the difference of pHe and pHi,was equal to zero,the pH of desorption solution was affected by the surface characteristics of minerals.The critical pH for the samples was V(7.7)>A_Al-Si>(6.9)>L(6.8)>A_Fe(6.%)>Kl(6.1)>G(4.2).

Abstract:The paper deals with the effect of MAP and DAP on zinc adsorbed by loess soil and the biological effect of MAP and DAP.The results show that the zinc-adsorption diagrams of loessial soil was similao to chat of Tucson loam in steeps obtained by Udo,E.J.The amount of zinc adsorbed by soil was effected by pH of different equilibrium Zn solutions of soil.The amount of zinc adsorbed by the parent material was higher than those by argillic horizon and rusEy dark loessial soil.MAP and DAP application had an important effect on the model of zinc adsorbed by soil.The amount of zinc adsorbed by soil was decreased by MAP application.Hovveverr the amount of zinc adsorbed by soil was increased by DAP application.The effects of MAP and DAP were specially obvious in the loessial soils with lower contents of O.M.and clay.The pH in two different system was a leading factor to control zinc adsorbed by soil,but the change of pH was affected by phosphate form.The results show that MAP could promote the adsorption of zinc by plant the interaction between zinc and phosphous,but DAP could decrease the amount of zinc adsorbed by plant and weaken the interaction between zinc and phosphate.Therefore,the zinc fertilizer applied togather with MAP is more beneficial than with DAP in the loessial soils deficient in zinc and phosphorus.

Abstract:Eight Dutch surface soils were used in this study to analyse different N fractions in 0.01 mo1L^-1 CaCl₂ extracts and percolates at different temperatures.The results obtained showed that:(1)The temperature of 0.01 mo1L^-1 CaCl₂ extracting and percolating solution had no influence on amount of NO₃^--N,the extractability of other N fractions (NH₄^2-,total soluble N and reduced N),however was evidently affected by the temperature in 0.01 mo1L^-1 CaCl₂ solution.The hydrolysis of organic N was the predominant reason for this influence.(2) The release of organic soluble N obeyed the first order kinetics.A nonlinear least square method could bestfit the experimental data into the model N_t=N₀(1-e^-kt) with Rsquared being than 0.99.(3) The kinetic values No were highly consistent with the soluble reduced N in extraction exeperiment.The 0.01 mo1L^-1 CaCl₂ sollution exetracted and released the labile organic N fraction.The determinations of soluble orgaraic N in 0.01 mo1L^-1 CaCl₂ solution looked promising as a property for prediction of N mineralization,N fertilization and N pollution.

Abstract:Field experiments were conducted to study the effects of nitrogen,phosphorus,potassium fertilizers and soil fertility on the nutritive composition of bamboo shoot.The results obtained showed that the bamboo shoat had much higher contents of total.and essential,amino acids than ather common vagetables.The free amino acids contents were higher in winter bamboo shoot than those in spring bamboo.The free glutamine and aspartate were the major delicious amino cids of the former,gl-atamate and aspartate were the major delecious amino acids of the latter.The hydrolytic and free amino acids contents of bamboo shoot were enhanced by N,P or K fertilization.But the sugar content was decreased with application of N fertilizer and increased with phosphorus addition.The results also indicated that the hydrolytic amino acids in winter bamboo shoot had a significantly positive correlation with soil available N,but no significant relation with K and P were observed.In addition,the free tryrosine content,which always resuits in turbidness of the canned bamboo shoot,was lowerd with increasing soil N or P conlient and fertilizer rates of N or P.

Abstract:The competitive adsorption of Zn,Ni and Co from 10^-4-10⁺⁶ molLu^-1 heavy metal ions solution containing 0.05mo1L^-1 Ca(NO₃)₂ (pH5.5) by three soils with different pl:ystcai and chemical properties was investigated.The results obtained showed that the amount of heavy metals adsorbed by soils was in the sequence: Yellow brown earth>Latosol>Red earth.The order of ion selectivity was: Zn>Ni≥Co.Obviously,the mechnism of competitive adsorption differed from that of non-competitive adsorption.Firstly,the quantity of competitive adsorption exceeded that of non-competitive adsorption.Most of all,the heavy metal ions,especially Zinc,adsorbed by the samples in which free iron oxide was removed increased to varying degrees instead of decreasing.Obviously,the effect of accompanying anion on the quantities of heavy metals adsorbed was greatly inhibited.The change of pH₅₀ which could reflect the interaction between soil and heavy metal ionsw Leas in consistent with the characteristics of adsorption isothirm.Secondly,according to the characteristics of adsorption and desorption of heavy metal ions,it might be considered that the adsorption sites on colloid surface in red earth were less than those in yellow brown earth and latosol,but red earth had a higher proportion of high energy adsorption sites than yellow brown earth and latosol.

Abstract:The present paper describes a nondestructive method in which gamma ray attenuation is used to determine the soil density and water content in a laboratory column.The,gamma ray apparatus consists of a radiation source,a detector,a counting system and a mounting flatform.The source is a 60 mcl cesium-137 with a peak gamma ray energy of 0661 MeV.The detector contains a sodium iodide (NaI) scintillation crystal of 4 cm diameter and 4 cm thick,a photomultiplier tube and a preamplifier.Sufficient shielding and collimating of gamma radiation is essential to improve space resolution and measurement accuracy,and to warrant personal safety.Collimation is required on both source and detector siides.In our equipment,the holes in source-side and detectorside collimators are 8 crn in length and 1 cm in diameter and then stanard errors less than 0.001 g/cm³ may be obtained for a 10 cm thick soil with a bulk density of 1.4 g/cm³.By means of shielding the source,collimating the beam and controlling the counting rate and time,percentage errors for the system may reach 1% and even less.To determine the soil density and water content with garruna ray attenuation,it is necessary to know mass absorption coefficients whnch depend only on material if the source is specified.The calibration experiments were conducted in Plexiglas containers.Measured mass absorption coefficiens for water,Plexiglas,sand,loam and clay were 00814,0.0775,0.0746,0.0744 and 0.0732 respectively.For the soil samples mentioned above,measurements were made at several points and averaged due to nonuniform packing.

Abstract:Under conditions of shallow water table,water flux pass through the root zone boundary is an unneglected component on calculation of water balance.With simultaneous measurements of soil water potential by a serise of tensiometers and of soil water content by neutron probe meter in soil profile,water flux pass through the boundary of root zone can be calculated by zero flux place method.However,if zero flux plane isn't appeared in the profile,it can be calculated by Darcy's formula with measurements of soil water potential near the boundary and soil water conductivities which are obtained beforehand.In a process of irrigation of wheat field by pumping water from well,zero flux plane was found in nonirrigated wheat field near the boundary of root zone,and its depth was followed by the fluctuation of water table.There fore,there was not only upward flux pass through the boundary during this process but also downward flux which was unfavourable for water supply to root system.

Abstract:This paper reports the results of biochemical and serological characteristic identification of thirty-eight fast-growing soybean rhizobia which were isolated from different soils and soybean cultivars of main soybean-producing are as in Shanxi Province.The cell component analysis,plasmid identification,and symbiotic effectiveness and competitive nodulation tests of some strains were carried out.The results showed that all of the isolated 38 strains were typical fast-growing rhizobia.The intrinsic antibiotic resistance of the isolated strsins were lower than that of Brddyrhizobium japonicum strains except to ampicillin.By cross-agglutination reaction and fluorescent antibody technique,38 isolated strains were divided into 4 serotypes,of which two were new serotypes and named Serovar 2077 and Serovar 2120.Nitrogen arid carbon contents of cell component were 2.01-3.78% and 50.52-55.53% respectively.The ratio of nitrogen to carbon was smaller than ten.Seven strains detected all contained one to two large plasmids and had one plasmid with a molecular weight of 112 Md or so.Because soybean eultivars were different,the symbiotic effectiveness and competitive nodulation of the isolated strains had distinct difference.The isolated strains were superior on soybean cultivar "Edou-2" to "Hefeng-29" in the symbiotic effectiveness.The dry weight and total nitrogen of plant of at least three strains were similar to those of USDAl10.When the isolates and slow-growing soybean rhisobia were mixed,the nodulation ratios of different soybean cultivars varied greatly.The nodulation ratio of fast-growing soybean rhizobia is far higlaer on boybean cultivar "Houzimao" than on cultivar "Hefeng".Research results show that there is a wide distribution of fast-gwoing soybean rhisobia in Shanxi province which is one of Chinese soybean origins.The isolation frequency is rather high,and there are more strain types in these isolates.

Abstract:This paper deals with clay minerals and primary minerals of soils which developed on sediments on the terraces and valley flat of ferent periods Wushui,the North River,Hengshishui and Lian River in Northern Guangdong.The result obtained showed that disparity in mineral composition depended upon differetzt sources of sediments in river valleys.In the same river valley,composition of soil minerals in the third terrace (T_a) which was developed from the Early pleistocene differed greatly from that in other terraces.It resulted from different conditions of weathering and soil formation and different sources of sed.imentary matter.In the Second terrace (T₂),the First terrace (T₁) and the valley flat (T_o),the composition of soil minerals were similar and sedimentary matter was basically the same,only weathering degree was different.The higher the terrace and the older the age of soil formation the stronger the allitic degree was.However,the disparity degree among the terraces was not the same.Because of time factor combined with climatic fluctuation T,diffened greatly from T₂ but less from T_o.

Abstract:The beach soils of intertidal zone and its immediate neibour above negative 5m isoline in east coast of Leizhou Peninsula have a area about 1.41X105ha.The beach soils are classified into one greatgroup,three subgroups and eight species.Because the vegetion is poor and mineral nutrient such as phosphorus and manganese in parent materials is low in the beach land,therefore,the contents of organic matter,nitrogen and phosphorus are low and contents of microelement such as Cu,Zn and Mn are loewr than mean levels of soil in China.The salinity of soils varies greatly with texture of soils and total salinity of seawater and ranges from<0.5% (sandy tidal flat soil) to 3.3%.The land surface water is not sufficient,but surfaces of beach are considerably flat and the topography is suitable for the protection from the wave in this area.It is good for the development of maricuture.A small fraction of beach soils such as muddy and sand-muddy tidal flat soils has the posibility for the reclaimation by embankment.The development prospect of the area is very promismg.

Abstract:在通常条件下,重金属在土壤中的溶解度主要取决于土壤对它们的吸附性能。不同重金属在同种土壤中的吸附顺序为:铅>铜>锌>镍>钴>镉。交换态重金属含量随pH的升高有最大值出现。出现最大值时pH的高低与重金属的专性吸附能力有关。土壤有机质和氧化物胶体对重金属有很大的吸附容量。且随pH升高而显著增大。升高pH,充分发挥土壤有机质和氧北物胶体对重金属的净化作用,可能是控制酸性土壤重金属污染的一个可行措施。对土壤中重金属元素的形态研究,无论在土壤科学还是环境科学中,均具有重要的意义。本项工作系应用逐级提取法把土壤中的重金属Cu,Zn,Cd,Pb,Co,Ni分为水溶态,交换态,有机结合态和闭蓄态四种不同的化学形态,研究土壤酸度对它们在各种形态中分配规律的影响。此外,对土壤重金属污染的控制途径也提出了一些尝试性建议。

Abstract:铅和镉都是环境中主要污染物质。随着工业“三废”的排放,它们的威胁越来越大,除直接对作物产量造成影响外,还在籽粒中大量积累,影响品质,危害人体健康,关系到“痛痛病”的发生^[1]与大工业城市犯罪率的增加¹⁾。因此,测定植株中铅和镉已经成为农化分析中的重要项目,而且还将一天比一天重要。