Abstract:The field evaporation process and the annual rate of crop evapo-transpirations in the experimental fields under lbcal climatic conditions were calculated by means of an empirical formula.Comparing data obtained with average raining process and amount of annual rainfall in the same fields,the results of water balance in black soils under different crops were obtained.Using these results to evaluate the adequate water supply to crops,we found that soybean and corn had a rather good reliability of water supply,but as for the spring wheat it appeared somewhat shortage,and was apt to suffer from drought.The seasonal frozen layer in black soil played an important role in the regulation of water supply,and the spring thaw in the frozen layer was the main source of water in the earlier stage of plant growth.Factors affecting spring drought were studied and methods for prediction of shrine droueht were sueeested.

Abstract:The rate of degradation of chloral in soils is in the following order:Quickest in salinized meadow soil,neat in paddy soil and slow in red soil.In general,when chloral exposed to the air and light,or in contact with an alkaline solution,it is liable to rupture at C-C bond and decompose into CHCl₃,Cl₂ etc.However,the transformation of chloral in soil proceeds chiefly to the formation of TCA instead of C-C bond rupture.The oxidation products have been identified by the derivative chromatography and by gas chromatography and mass-spectrography.The conversion rate of TCA from chloral was about 56%-76% with a persistent period of 70-100 days.

Abstract:In the eastern and southern China boron-deficient soils have been found in large areas,while soils in the arid regions are rather rich in boron.The amount of boron in soils varies with parent materials.Soils derived from shale,limestone,and marine sediment are usually rich in boron and those derived from granite and other igneous rocks,gneiss and sandstone are low in boron.Strong alkalinity and rich organic matter in soils reduce the availability of soil boron.Thus the boron-deficient soils may be divided into two types and four subtypes.

Abstract:The nitrogen balance and the availability of residual nitrogen of green manures in relation to their chemical composition were studied in pot and incubation experiments.Azovla,milk-vetch and common water hyacinth were used as green manures and labelled by the fertilization of (¹⁵NH₄)₂SO₄.Result obtained are summarized as follows:1.Although plant materials having lower C/N ratio usually give more available nitrogen and the C/N ratio of azolla was lower than that of milk-vetch,yet azolla contained high lignin about 20%,and consequently the percentage recovery of mitrogen by rice plant from azolIa was much lower than that from milk-vetch.

Abstract:A review on the effect of the plantation of aquatic plants on rice yield conducted by the authors in recent years is given.It is considered that the nitrogen cycle in the water layer is closely related to the nitrogen cycle in the underlying soil layer,and the plantation of aquatic plants in rice field showed beneficial effects on the nitrogen economy for rice growth.Another aquatic plant,pistia stratiotes,although does not possess the ability of fixing nitrogen from the atmosphere,reduced the loss of nitrogen brought in through irrigation water and fertilizers,and diffused from the underlying soil.The latter effect is quite important in decreasing the loss of fertilizer nitrogen.

Abstract:Present article deals with the reclamation of saline soils in Dayuzhang district at the coastal areas of Shandong province.Experiments were laid out in years 1973-1978.Irrigation water ways conducted from the Yellow river.Pumping wells in connection with open ditches were constructed for drainage.Detailed descriptions and records on the arrangement of drainage system,seasonal change of water movement in soil profile,change of salinity of soil water and in soil layers,effect of texture profile of the soil on the rate of drainage,and the rate of desalinization of experimental field were illustrated on Figures 1-9 and Tables 1-3 in the Chinese text.The legends of the figures and the headings of the tables are given in English.

Abstract:Present paper proposes a new characteristic index-the hydrophilicity value of soil (H) for studying soil hydrophilicity,and introduces its measuring method.H value is defined as a ratio of the volume of water to the volume of CCl₄,both of which are held by an unit quantity of soils.The magnitude of the H value was mainly related to the component of clay minerole in soils.The results obtained showed that H value was in following descending order:bentomite>kaolinite;chernozem>yellow brown earth and neutral paddy soil>red earth>laterite.The time needed to attain an equilibrium state of water holding of soils are positively correlated with the magnitude of H value.

Abstract:This article deals with the transformation of organic materials,and its effect on the properties of soda-saline soils.The results obtained are summarized as follows:1.Under given hydrothermal condition,the rate of transformation of organic materials in soda-saline soils as affected by microorganisms is as follows:Bacteria>Actinomycetes>Bacillus>Fungi.Azotobacter and cellulose decomposing bacteria multiplied very rapidly in the presence of added plant materials.They were beneficial to the transformation of organic materials and accumulation of nitrogen.

Abstract:Present article reports the effect of humic substances on the availability of rock phosphate to crop growth.Water culture experiments for wheat,tomato and rice were carried nut with both ordinary rock phosphate and radioactive rock phosphate as phosphate sources.Experiments showed nn evidence that the addition of sodium humate gave beneficial effect on the availability of phosphate from rock phosphate to crop growth.However,the stimulating effect of sodium humate on root growth can be observed in all cases.

Abstract:红壤、砖红壤以及在这些土壤上发育的水稻土,都呈酸性或强酸性反应,在栽培水稻时,农民素有施用石灰的习惯.近年来这些地区种植大麦的面积日益扩大,例如浙江金华地区1978年大麦种植面积即达54万亩.但在大麦栽培上普遍存在早衰低产现象,这是否和土壤酸度有关?不同石灰物质对大麦生长的影响如何?为此,我们进行了以下三方面的工作.