Abstract:In this paper the relationship between the parameters of the regression equation of nitrogen fertilizer efficiency for early rice plant,ŷ=a+bx+cx², and those of the equation of accumulated mineralied nitrogen curve,ŷ=Kxⁿ, is discussed.Experimental results showed that there were three couples of curve derived from the equtions which revealed similar trends in three grougs of paddy soil. Results also showed that a significant correlation existed between the garameters "K" and "a", as well as between the amount of soil nitrogen mineralized through eight weeks incubation and the amount of maximum nitrogen application described by "-b/2c".It is suggested that the characteristics of N response curve and the maximum amount of N application for early rice could be predicted through the determination of nitrogen mineralization by incubalion method.

Abstract:This paper deals with the application of LANDSAT images in survey of the distribution of the major soils including red earth, yellow-brown earth and cinnamon soil in Hubei Province, and the promotion of the reliability of LANDSAT image interpretation for the delimitation of the soils. Central conception and numerical analysis were used and soil colour, concretions, pH values, degree of base saturation and dominant clay minerals were selected as the diagnostic indexes, which were used for the delimitation of the main soil types in this region. The boundaries of distribution of the soils delineated by the methods mentdoned above well codncided with those of LANDSAT images.

Abstract:Some surface electrochemical properties of soils, including plio value, adsorption of K⁺ and Cl^- ions, degree of dissociation of K⁺ ions, bonding energy of K⁺ ions with the soil, and potassium hydroxide potential were investigated. Three pairs of soil samples, each with a paddy soil and its parent soil, representing different soil types, were aced for the study. One paddy soil was derived from latosol with more positive charge, one was derived from red earth, and another was derived from yellow-brown earth with more permanent negative charge and very little positive charge. The results showed that the surface electroehemioal properties were different in different types of paddy soil. The paddy soil derived from latosol contains less free iron oxides than its parent sail due to their removal by reductive eluviation during the development of paddy soil. This may result in the decrease in positive charge and inerease in the proportion of negative charge, hence the surface electrochemical properties of the paddy soil are remarkably different from its parent soil. The surface electro-chemical properties of paddy soils derived from yellow-brown earth and red earth showed no remarkable change during their development.

Abstract:1. Analytical results of enzyme activities of invertase, acid, alkaline and neutral phosphatase in 12 soil samples showed that enzyme activities in soils were closely related to soil horizons and decreased with the increase of soil depth. The intensity of enzyme activities in different soil horizons were in the sequence as follows:plough horizon>plough-pan> subsoil horizon. Catalase activity in soil was related to pH. Enzyme activity of polyphenol ogidase showed no rennarkable distribution regularity in soil profile. This enzyme in brown earth, yellow brown earth, purplish soil and yellow earth increased with the increase of soil depth. 2. Enzyme activities (except palyphenol oxidase) in black soil, red earth and yellow earth were closely related to soil organic matter. There are. also correlation among different enzyme activities. Activities of urease, catalase, invertase, protease and phosphatase in the soils with higher fertility were stronger than those in the soils with lower fertility. So enzyme activity could be used as an index for evaluation of soil fertility.

Abstract:In calcareous soils, after application of MnSO₄ for dozens of days, about 70% of applied Mn transformed into easily reducible Mn, yet, little applied Mn transformed into chelated or phosphate-soluble Mn. While the rates of Mn application increased, the amount of exchangeable Mn decreased significantly. This phenomenon, perhaps, could be attributed to the strong absorption of newly-formed Mn-oxides to soil Mn of eachangeable form. It was observed that the exchangeable and chelated Mn were very unstable in plant-grown mils, in fact, the violent uptake of plants. The easily reducible Mn, however, did not change very mach in a period of time, so it was easy to define the status of this form in a soil, what is more, this form was the only one that related with Mn uptake of plants. The conclusion is that in calcareous soils both chelated and exchangeable Mn are of little importance in the nutrient status of a soil and easily reducible Mn exceedingly affects soil Mn supply for plant requirement.

Abstract:Experiment using 100 field moist soil samples showed that potassium release was found in 96% of the samples after air-dried treatment. For the soils with higher release capacity of K, the correlation between uptake amount of K by wheat and rice and K content in moist soils was more significant than that between the uptake amount of K and K content in air-dried soils. It indicates that moist soil is suitable to be nerd for analysis of K in soils with higher release capacity of K and lowar content of slowly availsble K. Only a little K could be released from the moist soil containing abundant K after submergence and incubation. Through alternation of wetting and drying,more 8 could be released from the soils richer in hydromicas or montmorillonite. However, it was difficult to increase available K in the soils with lower release capacity of K through submergence or alternation of wetting and drying. The amount of released K increased with the increase of drying temperature. When the tempemature was lower than 200℃, the released K was mainly derived from slowly available K, while the temperature was up to 400℃, the released K was mostly derived from mineral K. Most of the released K under the temperature above 60℃, was not derived from adsorbed K. The increase of exchangeable K in moist soil after air drying was closely related to the saturation degree of K in the soil. More K could be released from the sails containing such minerals as hydromica. The fixation range of fertilizer K applied into moist soils was 18%-56%. Generally the fixation of K increased significantly with the increase of drying temperature. The fixation capacity of K was dependent on sail properties.

Abstract:The reagent p-Br-arsenazo, can react with calcium canon (Ca²⁺) in strong basic medium and form:stable green complex with a maximum light absorption at 635nm, The molar extinction coefficient is 9.0×10³, The curve of standard concentration of Ca²⁺ is a straight line in the range of 5-40μg Ca²⁺/25 ml, The interference of Fe³⁺ and Cu²⁺ can be eliminated by adding F^-(or PO₄^3-)and ascorbic acid respectively, while Ag⁺, Co²⁺, Sn⁴⁺, Bi³⁺, Cr³⁺ can be screened by adding trietha-nolamine, The relative errors for determination of Ca²⁺ in well water and extracting of soil samples range from -5.33% to 7.96%.

Abstract:The present paper deals mainly with the released mechanism of hydroxo group in the reaction of soils and clay minerals with neutral NaF solution. On the basis of the study, the method used for determining the hydroxo group and aquo group on the surface of sail colloids was modified. The experimental results showed that the release of hydroxo group from ligand exchange by F^- ions in the reaction between the samples and NaF solution was obvious, and most of hydroxo groups were released due to the formation of cryolite on the surface of soil colloids. The amount of hydroxo group released from complex solution was little and difficult to be distinguished from that released due to the solution of cryolite. Results of experiment showed that due to rapid reaction of samples treated with NaF solution for 2 hours, it could be minimized the influence of cryolite formation on the amount of hydroxo group released from ligand exchange to minimum. Therefore a suggestion of 2 hours for extraction in the procedure of determining the hydroxo group may be acceptable.Within the time for extraction mentioned above, from the difference between the amount of F^- ions absorbed by the samples and the amount of hydroxo group released from the samples, the amount of aquo group might be calculated. The influence of lig- and exchange between F^- and phosphate or silicate ions of the surface of soil colloids on the ambunt of aquo group may be negligible.

Abstract:Besides metal ions, the clays in lime concretion fluvioaquic soil (Shajiang black soil) can be also reacted with humic substance of weathered coal. The degree of organo-mineral complexation between lime concretion fluvio-aquic soil and weathered coal was about 84%. The more the weathered coal added, the lower the degree of complexaition was. The adsorption ability by soil for weathered coal may be expressed by the organic matter content in heavy fraction of soil, or by the organic matter content times the heavy fraction content. The experiment also showed that four factors, i.e. pH, the amount of Al(OH)₃ added, the times of alternate drying and wettiah and the amount of weathered coal added, could influence the adsorption of weathered coal by soil clay, but the last one was the dominant. The loosely combined humus was the main part of organic matter of weathered coal adsorbed by lime concretion fluvio-aquic soil. Its amount adsorbed was also influenced by the pH of the system. The loosely combined humus in heavy fraction wd organic matter in the fraction <2 μm of soil were directly proportional to the amount of organic. matter. in heavy fraction of soil.

Abstract:Organo-mineral fractions of different particle-sizes were isolated from plow layers of 10 paddy soils following removal of light fraction and ultrasonic dispersion in water. As compared with chemical method of dispersion, this method is better in separation of various mechanical separates. Acid hydrolysis of these fractions revealed that, for all the soils ezamined, the proportion of pentoses and neutral sugars increased with the increase of particle size, while the ratio of hezose/pentose and the proportion of NH₄⁺-N in acid hydrolyzates decreased with the increase of particle size. Two trends were observed in the variation of the content of organic C and composition of humus in different fractions of partieal sizes in the same soil. For soils developed on quaternary red clay and weathered product of extrusive rock in the middle subtropical region, organic C in the fraction of particle size<1 p was most abundant, while its molecular weight and aromaticity of humic substances as a whole judged from the humic acid/fulvic acid ratio and the E₄/E₆ of hnmze acid in the fraction were the lowest. For soils developed on the lacustrine deposLts in the northern subtropical regien, the organic matter in the fraction of particle size of 1-2μ was the richest, its molecular weight and aromaticity of humic acid were also the highest.

Abstract:The area of primitive forests on the north slope of the Changbai Mountains is one of the beat virgin forest regions reserved in northeast China. In order to study the influence of felling of the primRtive forests on the soil properties and its relation to natural reforestation, the field investigation was conducted from June to August in 1982. The main types of forest vegetation in this region are the pure larch forest, the broad-leaved Korean pine forest, the mixed coniferous forest and the mixed broad-leaved forest. gnd under these vegetations the main soils are mountain brown coniferous forest soils, mountain dark brown forest soil and lessive soil. These sail profiles are characterized by the thicker littear layer, higher content of humus and total nitrogen, which decrease rapddly downwards, pH-value ranging from 5.0-6.0, low degree of base saturation, higher content of hydrolytic acid, insignificant illuviation of iron oxide and aluminum oxide, C/N ratio ranging from 15 to 20 and good physical properties. It can be found that felling of the forest results in great changes of soil properties such as the accederated decomposition of litter, the increase of humus and total nitrogen in topsoil, the decrease of soil acidity, and the improvement of physical and moisture properties of the soil, which are favourable for the reforestation. However, clear felling in a too large area will bring about the flourishing growth of the wild grasses and dense development. of their roots in the topsoil, which is unfavourable for the nahural vend artificial reforestation. Therefore, the ra.tionable felling, i.e. selective felling,rather than the clear felling should be adopted, and the intensity of selective felling should be 40-50%. On the clear felling slash, careful preparation of soil before artifical reforestation is necessary, and proper tending of the young growth is of most important for its rapid growth.

Abstract:灌淤土是宁夏引黄灌区的主要耕作土壤之一,约占全灌区面积的50%,占耕地面积的80%。从五十年代开始,我们已注意到这种土壤的形成和灌淤熟化的特点,将其命名为草甸灌溉熟土^[1]。1978年全国土壤分类会议,定名为灌淤土,在全国分类系统中,划分出这个新的土类^[2]。

Abstract:雨水中含有的营养元素除硫外通常很少,不能满足作物的需要。如氮,钾仅能供给作物需要的百分之几。但是,雨水中所含的元素,对土壤养分的循环和平衡,以及环境生态的研究,有着重要的意义。

Abstract:土壤中的锆、铪来源于成土母质,其含量都比较低,锆的浓度一般在1000ppm以下,铪则在20ppm以下。由于锆和铪的共存关系以及它们在土壤中有高度的稳定性,因此可通过对土壤中锆和铪的研究来探讨土壤生成发育和成土母质的来源,以及监测环境污染^[1,5,6]。

Abstract:The problem of genetic classification of yellow earths has been mentioned by the writer in the report "A Soil Survey on the Jiulong Mountain of Zhejiang Province". However, up to the present, some points regardW g the chara,oteristics, genesis, distribution or even physical and chemical properties of yellow earth still remains confused. It is worth studying whether yellow earth is the product of moist climate, or it is formed from the hydration of ferric oxide.It is suggested that yellow earth should be merged with the red earth into one great group of yellow-red earth in the classification system, in view of the failure to find significant criteria to distinguish the yellow earth from the red earth, the typical primart yellow earth has not been discovered in southern China, where only the secondary yellow-red earth derived from the paleo-red clay could be found. Some soils of yellow colour may be due to the mineral composntion of the parent rocks, but not the influence of humid climate. Under normal presanre and temperature conditions, the hydrated iron oxide is difficult to be dehydrated, and iron oxide is also difficult to be hydrated. Therefore in nature there exists neither a model formula of soil genesis as yellow brown earth-yellow earth-red earth, nor a soil zone of yellow earth. In the mountain areas of southern China,there is a wide distribution of the paleored clay soil, which greatly influence the forestation of this region. It is proposed that the classification of the yellow earth should be based on its soil genetic properties under actual condition, but not be over-stressed on its zonality. After all, the formation of red earth one yellow earth as well as their mutual changes still remain puzzling.