Abstract:Based on the introduction of the 15th World Congress of Soil Science and the Developmental trends of soil science in the 21st century, a comprehensive analysis is made on the tasks of soil science to be carried over to the next century and some. new ideaa are put forward in the article.

Abstract:This paper summarizes the distribution of iron oxides in red and forest soils of Taiwan, using the high gradient magnetic separation (HGMS) technique. Soil iron oxides were measured by the methods including wet chemistry, X-ray diffraction (XRD), magnetic measurement, transmission electron microscope (TEM) and electron diffraction, Fe-57 Mossbauer analysis, etc. Acidic red soils developed from andesitic rocks of Ta-Tun, and Lu-Tau, Lau-Hsu and Peng-Hu calcareous red soils developed from basaltic rocks showed high magnetic susceptibility and contained ferrimagnetic minerals of magnetite or maghemite. Goethite and/or hematite could be identified in the most red soils. The clays accumulated in B horizons of the Shou-Ka soils and podzols occurring on high mountains were found to contain lepidocrocite. Magnetic clay fractions of Shou-Ka soils characterized by XRD and Fe-57 Mossbauer analysis showed that Shou- Ka soils contained goethite, lepidocrocite, poor crystalline hematite and iron-rich chlorite. Structural Fe²⁺ in iron-rich chlorite was located at talc-like cis-OH (M2) sites. The observations of TEM and electron diffraction of forest soils showed that goethite was lath-shape and indexed as(100) plane.

Abstract:Iron oxides in the soil clay and coaser fractions of three vertical soil zones of Fujian Province were studied by Mössbauer spectroscopy, chemical analysis and microscope examination. The results showed that from yellow soil to yellow-red soil to red soil to lateritic red soil,hematite increased gradually while goethite decreased gradually; the combination of iron oxides in the coaser fraction became more and more simple.From yellow soil to yellow-red soil to red soil, the free degree of iron and the ratio of crystalline iron oxide to colloidal iron oxide increased gradually while the activity of iron oxide decreased. However, lateritic red soil was an exception, which may be attributed to its young age. It is suggested that the relarive contents and the status of the iron oxides can reflect the stages of soil weathering and soil formation. Some problems concerning soil classification were also discussed.

Abstract:Four typical profiles of albic soils in China were collected to study the properties and geochemical variability of amorphous oxides collected to study the properties and geochemical variability of amorphous oxides of iron, manganese and aluminum.

Abstract:This paper deals with the eftect of application of organic materials on the optical properties of humic acids (HAs) from brown earth, meadow soil and paddy soil. The results obtained are summarized as follows: Application of organic materials led to the decrease of E₂₆₅,E₄₆₅ and RF values and increase of Δlog K of HAs. The shoulder-like absorption at 285nm originated from ligrin in ultraviolet spectra of HAs from the organic manure amended soil became more apparent as compared with that of the soil without organic manure application. The maximum-intensity wavelengths of fluorence excitation spectra(λ_ex) and the intensity of fluorescence emossion excitation spectra of HAs were reduced by application of organic materials. However, the maximum-intensity wavelengths of fluoresce emission spectra(λ_em) remained unchanged (about 546nm),no matter whether organic material was applied or not.

Abstract:Spatial sutocorrelation is one of the basic characteristics of regionalized variable, and statistics based on spatial autocorrelation can be used to test if the distribution of a variable in a two-dimentional space follows a certain pattern or at random. Values of Moran's I of trace element contents in soil of Tianjin plain area were calculated. The spatial sutocorreiation characteristics, the directional characteristics of spatial autocorrelation, the relationship between spatial autocorrelation and lag of sapmling and the relationship between spatial autocorrelation in different directions and lag of sampling were investigated.Under the sampling density of 300 km² per sample, significant by positive spatial sutocorrelations were detected for most trace elements studied. The most significant spatial autocorrelation was found in horizon A where the original distribution of the elements had been modified remarkably by natural forces and human activities. The spatial structure characteristics of Hg, Cd, Pb, Zn, and As contents in surface soil were further altered by pollution and agricultural practice.

Abstract:This paper deals with the spectral characteristics of main types of soils in southern China. Meanwhile, using methods of principal component analysis (PCA) and fuzzy category, 33 samples are classified according to 10 spectral character indexs. The results are compared with traditional soil classification and Chinese Soil Taxonomic Classification. The relationships between the spectral characters and physical and chemical proparties of the soils have been also investigated. The results show that different soil groups give different spectral reflectance curves, including flat type of latosels developed from basalts, slope type of the paddy soils and steep type of red soils and yellow soils sequences; the suitability between soil spectral character classofication and parent material types is very high L and by the method of PCA, it can be found soil spectral classification is identical to traditional soil classification in some senses. Then, as paddy soils and andosols are deeply affected by natural zonal factors, they can be sorted into different groups of zonal soils. Using soil spectral characteristic indexes and other classification indexes (e.g. clay SiO₂/Al₂O₃ of subsoil, CEC, coarse silt/clay, etc.),the soils can be classified effectively, the results are consistent with those obtained based on Chinese Soil Taxonomic Classification. The soil spectral characteristic indexes is especially suitable to be used for the division of soil genus, and the suitability between soil spectral characteristic classification and soil genus classification is more than 83 percent.

Abstract:Elovich, parabolic diffusion, power function and exponential equations were used to desoribe K desorption kinetics of 12 soils in a constant electric field of EUF. Results showed that the Elovich, parabolic diffusion and power function equation could desoribe K desorption kinetics well, owing to the high correlation coefficients and low standard errors; but the exponential was not suitable to be used in this experiment, due to the relatively low correlation coefficients and relatively high standard errors. This paper established successfully the relationships between the kinetic equations and the barley responses to K fertilizer in the field experiments and K status of soils, the contants (slope or intercept) of Elovich, parabolic diffusion and power function equations were highly significantly or significantly correlated to the soil exchangeable K, relative yeild of barley(NP×100%/NPK) and K uptake by bariey in the NP plot. It was suggested that the kinetic equation constants could be used to evaluate K-su pplying power of soil.

Abstract:pH changes and K uptake by nine rice varieties in a solution containing 0.1 mmol/L K₂SO₄ plus 0.2 mmol/L CaSO₄ were measured in the study. Changes of pH and K concentration were strongly correlated over 2 and 4 hours, which could be the basis for the establishment of a rapid and simple method for screening, selecting rice varieties with a high rate of K uptake. Based on the total K uptake by rice in a successive cropping experiment, the greater part of its K requirement was obtained from non-exchangeable sources. Total K uptake by rice varieties was significantly correlated with non-exchangeable potassium and potassium in extractable with 1 mol/L HNO₃ and mineral potassium, which could be used as criteria for screening high potassium-absorbing rice varieties. Yield responses of rice varieties to K application were studied as well.

Abstract:A systematic approach for soil nutrient status study was introduced to China in 1988. The method includes 1) soil sampling; 2) soil testing for 11 nutrients content; 3) soil adsorption for 7 nutrients; 4) greenhouse study; and 5) field experiment. Pot experiments have been conducted to study nutrient status of 104 soils from 13 provinces. Of the 104 soils, 100 were deficient in N, 101 deficient in P,60 deficient in K, 38 deficient in Zn, 23 deficient in S and 22 deficient in B. The number of soils showing deficiency in Mo,Ca,Mg,Cu,Mn and Fe was 19,18,14,13,11 and 3, respectively. The findings in greenhouse study have been verified in field experiments of selected soils.

Abstract:The features of water-salt movement, the techniques of protecting seedling against salt injury and the cultural measures about scientifical application of fertilizers and rational condensed planting were studied in the work. On this basis, the comprehensive cultural measures of high-yielding beet on saline-alkali soils in the Datong basin are put forward.

Abstract:开发利用改良海涂土壤,扩大耕地面积,发展农业生产,是缓和沿海地区人地矛盾的基本途径.莆田县人民围海造田,利用改良盐土,有着悠久历史和丰富经验.客土造地法是沿海旱作区利用改良盐土的有效途径.它是因地制宜,就地取材,在重盐土地上,客人150-250t/ha非盐化土壤物质,人工创造25-35cm厚的堆垫耕作层,做到当年实施,当年收成.本文研究了不同客土物质的改良效果,土壤形态、盐分和理化性质的变化,并提出了巩固改良效果的一些措施.

Abstract:取土钻是在土壤、地质、水利、环保等领域广泛应用,主要用于采集土壤样本的一种工具.它的产生、发展及应用大量取代了原始挖掘工具,不仅可以大大减少土壤调查工作量,缩短外业调查周期,而且还避免了作物生长季节,进行土壤调查时因挖剖面坑造成的作物损失,从而大大节省费用的支出.因此,取土钻在土壤调查中的应用有广泛的前景,但现有的土钻其性能还不能完全满足土壤调查的要求,鉴于此,我们于1989年开始进行了新型土钻的研究工作,现已完成新型直压式手动原状土取土钻的设计及试制,效果良好,达到预期的目标,并获得了国家的专利.

Abstract:钻(CO)是微量元素之一,并早已被证实是人和动物的必需营养元素,是蓝藻、微生物和豆科植物固氮作用所必需的元素,而且能促进植物增产,改进植物品质.但迄今为止,还尚未证实它为所有高等植物所必需^[1-5,9-12].