Abstract:Fertilizer experiments on citronella grass (Cymbopogon winterianus Jowitt) were conducted on the lateritic red soil originated mainly from the weathered crust of basaltic materials in the northern part of Laichow peninsula, Kwangtung. The experiments covered the complete life cycle of citronella grass during the period from 1960 to 1963. The soil contains 2.21% of organic matter, 0.10% of nitrogen, and 8 mg/100 gm of exchangeable potassium, but it is low in available phosphorus. Chemical fertilizers were applied with compost as basic manure which was prepared from the distilled material of citronella grass and was dressed at a rate of 15,000 kg per hectare. The muddy compost contains only 11.63% of organic matter.

Abstract:The weathering sequency of clay minerals is usually regarded as one of the important indexes for the classification of genetic soil groups. After a detailed review on literatures concerning tropic soils it is found that a great deal of confusion has been made in this respect. Actually some red soils are derived from highly weathered materials of earlier geological ages, and they inherit their clay minerals largely from old ferruginous crust. Others are young residual soils derived directly from various parent rocks. Composition of clay minerals of the latter soils reflects an incipient stage of present soil forming process. Soils having great diversity of SiO₂/Al₂O₃ and SiO₂/R₂O₃ ratios can be found in a restricted area in tropic and subtropic regions. Such divergent soil types were found in Kunming district, Yt}nnan through a detailed soil survey in 1958-1962.

Abstract:The present paper deals with the frequency distribution of clay minerals in the soils of China. The soils in the arid and semiarid regions of northern China contain large amount of illite. South of the Hwai River, the content of illite is decreased markedly with the increase of rainfall. However, illite is still dominant in the soils derived from micaceous parent materials. Except the laterite and some terra-rossa, all soils including red and yellow earths contain more or less illite. Vermiculite and chlorite are always associated with mica and illite. In the soils of semiarid and subhumid regions, vermiculite is a common accessory mineral of illite. In the tropic and subtropic regions, vermiculite is usually associated with kaolin in the red and yellow earths, but not found in the laterites. Montmorillonite has been identified in the clays of chernozem and chestnut earth. Small amount of montmorillonite is also found in rendzinas, paddy soils and some young soils derived from recent effusive volcanic rocks.

Abstract:The constituents of clay minerals in 11 soil profiles of Tibetan highland were identified by chemical analysis, canon-exchange capacity determination, differential thermal analysis and X-ray diffraction. The mineral constituents in the clay fractions of alpine and subalpine soils of northern Tibet are very similar, illite being predominant, accompanied with kaolinite and vermiculite and sometimes small amounts of chlorite and montmorillonite. Besides, some amorphous free iron oxide is also present in the surface layer of alpine soils. There ace significant differences in clay mineral constituents between the alpine and subalpine soils of southern Tibet. The clay fraction of alpine meadow soil derived from phyllite is similar to that of alpine soils in northern Tibet, but is quite different from that of subalpine soils derived from similar parent material, which contain greater amount of poorly crystallized kaolinite together with some vermiculite, gibbsite, mont-morillonite and interstratified mineral (12.6 Å). Except in the surface layer, the content of illite in the profile of subalpine meadow soil of southern Tibet is very low. Gibbsite usually accumulates in the upper horizons, while montmorillonite often found in the lower horizons. In the mountain shrub-steppe soils, the clay minerals consist mainly of an association of illite, kaolinite and vermiculite accompanied with montmorillonite, which increases in the calcareous layers, but no gibbsite is found. In the mountain podzolic soil from granite origin, illite, kaolinite and vermiculite occur in all horizons. Besides, a great amounts of montmorillonite accumulate in A₂,and gibbsite appears in the humus accumulating layer. The clay minerals of mountain brown forest soil (also from granite origin) consist mainly of illite, kaolinite, gibbsite and iron oxides, the amount of vermiculite and montmorillonite is small. It is very clear that the clay mineral constituents of the soils of Tibetan highland vary under different bio-climatic conditions. Illite occurs abundantly in the cool dry alpine tract, much vermiculite in the semiarid mountain regions along the River Tsanpo; while kaolinite and gibbsite in large amount in the warm moist region of southern Tibet.

Abstract:In this study the physical properties of surface soil were investigated under diffecent conditions. From the results obtained, we may come to the conclusion that good soil physical properties, which are resistant to soil erosion, are exhibited by high content of organic matter, large quantity of > 0.25 mm total aggregate and 1-10 mm aggregate, and the state and degree of micro-aggregation. We have also studied the twa soil physical constants, dispersion ratio and erosion ratio, which Middleton used to separate erosive from nonerosive soils. The results showed that both ratios increased following the cultivation of grass land, and that the heavier the soil, the smaller the ratios. These findings agree with that of Middleton. However, he used the erosion ratio "10" as a demarcation point between erosive and nonerosive soils. In our study, we found the erosion ratio of the heavy soil, which was the lowest, even reached as high as "19.0". Looking at this, it seems that all soils in this region should be erosive. Hence, further study is needed on the point of demarcation of erosion ratio when used in loess region.

Abstract:In the present study, the ferrous iron in paddy soils was classified and determined separately into four forms, namely, water-soluble, exchangeable, complexed and precipitated. Laboratory experiments were also made to elucidate their interrelationships with regard to amount, transformation and factors affecting their equilibrium. It was found that for ordinary paddy soils the water-soluble and exchangeable forms ranged each to less than 1-1.5 per cent of the total ferrous iron, and the percentage was each raised to more than 20 after the addition of easily-decomposable organic matter. The amount of ferrous iron complexed by solid phase fluctuated within 16-36 percent of the total ferrous iron. The amount of the exchangeable ferrous iron is influenced by the ration-exchange capacity of the soil, the amount of sulfide present and the prevailing pH. The amount increased with the increasing of soil acidity until pH 4 but decreased thereafter, presumably due to the competition for the exchange site by hydrogen and aluminum ions in the latter case. The adsorption of ferrous iron by soils leads to an equivalent liberation of calcium ions to the liquid phase.

Abstract:It was found that the sign of the suspension effect is closely related with the electric charge of the solid particles. For laterite, red loam and coagulated albumin, there appeared an acid suspension effect at higher pH and alkaline effect at lower pH, with a zero ΔpH between the suspension and the supernatent solution at their isoelectric points. When either the glass electrode or the calomel electrode is transferred from the solution to the suspension or vice versa, suspension effect will result. The relative magnitude contributed by the two electrodes depends on the pH value. For the laterite with an iso-electric point of about pH 5.0, the sign of ΔpH due to the glass electrode is always negative and its numerical value increases with pH, whereas the sign of ΔpH due to liquid junction potentials depends on the pH of the suspension, being rather small in magnitude at higher pH. Further observations revealed that factors influencing the liquid iunction potentials are rather complicated indeed.In addition to the sign of the net charge of the particles,many other factors,such as the kind of cations participating in the diffusion process between the two phases as well as the diffusion conditions,may all influence the diffusion potential to some extent.The volume charge density of the sediment also affects the magnitude of the liquid iunction potential.For negatively charged clays,exchangeable hydrogen or sodium ions caused a norfnal negative △pH,calcium ions rendered the liquid junction potential to drop,and at lower pH the sign of △pH caused by trivalent aluminum ions may be reversed from what had been suspected.Stirring of the system affects the pH reading markedly.This effect is confined exclusively to the liquid iunction Potential.

Abstract:Tile alkali soil is one kind of alkalized light meadow soils in the Northern Plain of China. It is characterized by high pH value, low concentration of soluble salts, and crusting of surface soil under drying condition. The crusting of surface soil is a serious hazard to seedling emergence, and the high pH value of the soil affects the growth of crop plants. These properties of the soil are related with the high percentage of exchangeable sodium on the colloids of the tile alkali soil. For the improvement of the colloidal properties of this soil, it is necessary to displace the excess exchangeable sodium on soil colloids with calcium (CaSO₄,organic matter and sulphur). Breaking the crust mechanically improves the soil physical properties only temporarily.

Abstract:Studies of the uptake of phosphorus by plant from soils and phosphatic fertilizers were conducted in pot culture experiments with the application of irradiated rock phosphate powder and labelled superphosphate. The soils used were a red soil, a yellow drab soil of slightly acid reaction and a calcareous light colored meadow soil. Fractionation of soil phosphorus was given in the report. Experiments revealed that, when powdered rock phosphate was applied to a calcareous light colored meadow soil at the rate of 5.64 grams per 6.0 kilograms of soil, no response in crop yield was observed, although the plants took up 35% of their absorbed phosphorus from the fertilizer. In a similar experiment with red soil deficient in phosphorus, more than 80% of the plant phosphorus was originated from rock phosphate, and soyabean and buckwheat showed marked increase in yield with the application of this fertilizer. In the experiment with yellow drab soil, millets took up almost equal amounts of phosphorus from the soil and rock phosphate, and significant response in yield of grains was found. When a mixture of 5.64 grams of powdered rock phosphate and 0.90 grams of superphosphate was applied to each of the above mentioned soils, it was found that the proportion of uptake of phosphorus by millet in a calcareous light colored meadow soil was 40 from soil;42 from superphosphate; 18 from rock phosphate. The proportion of phosphorus uptake by millet in a yellow drab soil from the respective sources was 54:12:34 and by soyabean in a red soil, 15:4:81.When powdered rock phosphate was incubated with organic manure, tracing technic showed that no increase in the availability of rock phosphate to wheat was observed after incubation.

Abstract:Автор изучал состав гумусовых веществ желто-бурых лесных и пахотных почв врайоне гор Цзыдиньшань под городом Нанкин,он характеризуется слвдующими признаками.

Abstract:По историческим материалам процесс развития засоленных почв в южной части провинции Хзбзй от Ⅳ-го до начала ХХ-го века можно разделить на три стадии.

Abstract:1. Относительное содержание гумусовых веществ микроагрегатов 3 фракций (G₀,G₁,G₂)и остатков в желто-бурых поприблизительно составляет 2:4:3:1.