Abstract:This paper is one part of the study on the essence of soil fertility.It proves again that the characteristics of binding status and the content of various components of soil humic substances and the quantitative distribution of different fractions of microaggregates strongly influence the "physique" and the "pedon structure" of soil.The constituent characteristics and functioning mechanism of fundamental substances of fertility in red earth are related to a certain eztent to the higher content of free ferric oxides in soil and their different distribution in various fractions of microaggregates.

Abstract:Quantitative studies on changes in C/N ratio,N,P,K.Ca and Mg contents of red clover and rye grass residues during decomposition in agroecosystems under no-tillage (NT) and conventional tillage (CT) were carried out in Horseshoe Bend,Ga,USA.Results showed that the decomposition patterns and mineralization rates of nutrients in the crop residues were different in the two ecosystems.Both the mineralization and biological immobilization of elements toolz place earlier in CT system than those in NT system.It was found that the amounts of nutrients elements remaining in residue,decreased rapidly in CT systems.

Abstract:The experiment results in this report are summariued as follows:1.Both of the reduction treatments (with glucose) and chelatim treatments (with oxalic acid) could aotivate and remove certain amount of Fe₂O₃ or Al₂O₃ from the soil and deteriorated the soil structure containing macro- and micro-aggregates.2.The reduction-chelation treatments (with citrate-dithionitc:solution)could activate and remove a large amount of Fe₂O₃ and Al₂O₃ and strongly deteriorated the soil structure.

Abstract:A comparison between the slope of the adsorption isotherm of phosphate and that of fluoride shows that the adsorption of phosphate is stronger than that of fluoride.The adsorbed phosghate on goethite surface is made.up of two types,i.e.,the isotopically exchangeable and non-exchangeable.The proportion of non-exchangeable phosghate to total adsombed phosphate at a low level of adsorption is greater than that at a high level of adsorption.The amount of non-exchangeable phosphate is not affected by the equilibrium concentration of phosphate in suspension.The effect of fluoride on the adsorption of phosphate is very weak.On the other hand,phosphate has a strong effect on the adsorption of fluoride when a competitive adsorption of these anion species occurs.The adsorption of phosphate is not affected by fluoride when phosphate is adsorbed first,or when phosphate and fluoride are adsorbed simultaneously.However,fluoride has certain effect on the adsorption of phosphate if fluoride is adsorbed first.When phosphate is adsorbed first,the amount of adsorbed fluoride is always less than that when fluoride and phosphate are adsorbed simultaneously,and it is ereatest when fluoride is adsorbed first.

Abstract:This paper deals with the distribution of amino acids and nitrogen in organo-mineral complex of periodically waterlogged paddy soils developed on red earth and waterlogged paddy soil developed on lacustriue deposits with various nitrogen levels in Zhejiang province.The results of experiments are summarized as follows:1.The nitrogen content in organo-miineral complex increased with increasing nitrogen content in soil samples.For different fractions of organo-mineral complex,the nitrogen contents were G₂>G₁>G₀.The percentage of alkali hydrolysable and pyrophosphate extractable hosphate extractable nitrogen in G₀ of waterlogged paddy soil was higher than that in G₂ or G₁,but for periodically waterlogged paddy soils,that in G₂ was higher than that in G₀ and G₁.

Abstract:The present paper deals with the adsorption and desorption of fluoride by two soils (latosol and yellow brown earth) and two synthetic iron oxides (amorphous iron ozide and goethite) in NaF solutions.On the basis of the characteristics of adsorption isotherms,Langnuir equation (C/X=1/a·X_m+C/X_m) fits best for the experimental data of Latosol and amorphous iron ozide,but Freundlich equation fits best for those of yellow brown earth and goethite.The amount of fluoride desorbed is lower than that of the fluoride adsorbed.It is possible that part of the fluoride adsorbed by electrostatic force was removed due to washing with water and alcohol.

Abstract:The genetic process of the soils on Hengshan Mt.in Hunan province are getting stronger with the increase of the altitude,and the vertical sequence of the soils from the mountain foot to the summit is in the order of red earth,mountain yellow earth and mountain meadow soil.This regularity is well reflected in the constituents of the clay minnrale of the soils.It was found that the quantity of kaolinite decreased and that of gibbsite increased with the increase of the altitude.however,hallaysite existed in almost all the soils,especially in layer B and C horizons.The weak-weathered clay minerala such as hydromica,hydrobiotite,and chlorite mainly exist in the soils on upper hart of the mountain.

Abstract:The transformation of nitrogen was studied in a well-drained paddy soil by adding ¹⁵N labelled cratalaria,¹⁵N labelled wheat straw,(¹⁵NH₄)₂SO₄ and (¹⁵NH₄)₂SO₄ together with cellulos so as to adjust the C/N ratio of applied fertilizer from zero to 50 at the same N level.Rice was planted under three soil water regimes,i.e.submerged condition,submerged and percolated condition (1.5 cm/day),and dryland condition kept with 60% W.H.C.

Abstract:1.The results of experiments showed that,in calcareous chernozem and light chernozem,the inorganic-P accounted for 70——85%,Ca-p 25——48%,Al-P 4.2-7.6%,and Fe-P 1.4——2.4% of total P;in neutral black soil,inorganie-P was 40——50%.Ca-P 14——15%,Al-P 4——5% and Fe-p 4——5% of total P.The data indicate that the contents of vatious forms kof inorganic P in the two soil are in a descending order of Ca-P>Al-p>Fe-P.2.Plant analysis showed that the recovery rete of phosphorus by wheat was in a descending order of Al-P>Fe-P>Ca-P,less Ca-P was absorbed althoagh it was more in soil.

Abstract:Present paper deals with the application of air photo-analysis and interpretation of the soils in the hilly region with more complex landforms in combination with detailed soil survey following reconnaissance survey along selected lines in model aeras with typical landforms.The qualitative features of soils and the factors interfering soil interpretation were analysed by stereoscopy.The soils were discriminated by landforms,rock types,vegetations (indicator plants),and land use patterns in combination with analysis of other envionmental conditaons.The soils could be discriminated from the level of great group to that of genus.The results obtained showed that the qualitative interpretation accuracies were 98.6%,92.5%,and 86.3% respectively at the level of great group,subgroup,and genus.The quantitative accuracy (of bounderies between aeras) was 75.3%.It amounted to 86.6%,if the areas of natural and cultivated purple soils which were difficult to discriminate were deducted.

Abstract:The soil species of paddy soil are generally classified on the basis of the patterns of solum structure and the development degree of the diagnostic horizon.Therefore,the basic horizons of paddy soil should be established and the criteria for division of the horizons in soil solum should be defined in advance.Owing to the different patterns of solum structure,the developmant degree of the diagnostic horizon in subsoil is different.For example,in addition to the differences in morphological features,the periodically waterlogged paddy soil with moderately developed percogenic horizon is rich in crystalline iron and higher in ratio of crystalline iron to the amorphous iron in the horizon;and the soil with weakly developed percogenie horizon is commonly less in crystalline iron a.nd lower in the ratio of crystalline iron to amorphous iron in the horizon;while the soil with well developed percogenic horizon is rich in amorphous iron in the horizon.

Abstract:美国著名土壤科学家Truog也是测土施肥科学创始人之一,他于1960年第七次国际土壤学会上做了题为“测土工作五十年”的报告.他对测土施肥研究十分重视,并提出其独创的观念与方法,其要点是:(1)100蒲式尔产量的玉米总共吸收150磅N,60磅P₂O,与120磅K₂O,这已被多年实验所证实;(2)在作物吸肥过程中,土壤供应多少养分?