Abstract:First, this paper discusses ion diffusion kinetics in soil systems theoritically. Ion diffusion kinetics in soils can be classified into three types: negative first-order, zero-order and first-order kinetics. Based on this, an experiment on Mg²⁺ diffusion kinetics was done in soil and quartz sand systems. The results showed that Mg²⁺ diffusion kinetics in the two systems were a first-order kinetic process. But at the temperature of 298K and in the initial stage of diffusion, first-order and negative first-order kinetic processes coexisted in Mg²⁺ diffusion in the soil system. Through the study of Mg²⁺ diffusion in quartz sand systems, we also found that an exchange reaction might take place between Mg²⁺ and hydrogen at the hydration SiO₂ surface, and the Mg²⁺ which took part in exchange reaction was at diffused in the quartz sand within the initial ten minutes.

Abstract:A series of simulation experiments were conducted to study the successive pollution effects of applied inorganic arsenic on soil by the method of successive application of arsenic at the same rate. Buffering dynamic process of soil to As and its characteristics were studied. A buffering dynamic velocity rate equation was developed. This is thoueht to be the basis of study on buffering capacity of soil to As.

Abstract:The Cu²⁺ adsorption on Ca-montmorillonite and δ-Al₂O₃ in the presence and absence of three pesticides, glyphosate, picloram and chlordimeform, was studied. Glyphosate markedly reduced the adsorption of Cu²⁺ on Ca-montmorillonite by complexing with Cu²⁺ ions. The higher the mole ratio of glyphosate to Cu²⁺, the more the decrease of the Cu²⁺ adsorbed. Glyphosate increased the Cu²⁺ adsorption on δ-Al₂O₃ through "bridge" bonding with δ-Al₂O₃ and Cu²⁺. The higher the mole ratio of glyphosate to Cu²⁺, the more the increase of Cu²⁺ adsorbed on δ-Al₂O₃. Picloram also decreased slightly the adsorption of Cu²⁺ on Ca-montmorillonite by means of complexing with Cu²⁺. However, it did not influence obviously the adsorption of Cu²⁺ on δ-Al₂O₃. Chlordimeform decreased the Cu²⁺ adsorption on Ca-montmorillonite through competing for the adsorption sites with Cu²⁺ ions while it showed no effect on Cu²⁺ adsorption on δ-Al₂O₃.

Abstract:Water-repellent soils are difficult to wet and cause crop production losses and land erosion by wind and runoff. Research programs on soil water repellency have been conducted in Australia, the Netherlands, New Zealand and America for many years. Because wetting patterns in water-repellent soils are quite irregular and incomplete, there has been no successful model for heat and water movement in water-repellent soils. Based on our tillage research work in water-repellent soils in Western Australia, the water movement in furrow sown water-repellent sandy soils is quite regular. As making furrows, the extremely water-repellent surface soils are moved to form the ridges with dry cores. This leads to rainfall runoff from the ridge and infiltration into furrow. Furrow tillage not only increased the gemination, but also make it possible to develop a model. A numerical model of heat and water movement in furrow sown water-repellent sand was developed and validated by the authors in Western Australia in 1991.

Abstract:Based on the experimential data obtained from winter wheat and corn in field and growth box, the differences of hydraulic resistance between steady water flow and unsteady water flow in the soil winter wheat and soil-corn system were studied in this work. The results indicated that under unsteady environmental conditions the model of steady water flow was not accurate, but, instead, the model of unsteady water flow should be valued.

Abstract:The study on characters of phosphorus supply and response to phosphatic fertilizer showed that inorganic p and organic P accounted for 91.12% and 8.87% respectively. In the former Ca-P,O-P, Al-P and Fe-P accounted for 86.1%,9.6%, 3.0% and 1.3% respectively. The relation between inorganic-P forms and rapidly available phosphorus (RAP) could be described by y(RAP)=49.30x_1(AL-P)+21.8547x_4(Ca-P)-3.4209, which indicated the significance of Al-P and Ca-P to RAP and the feasibility that iron and aluminum phosphates and calcium phosphates served as soures to soil P. The growth and decline of total P and available P deponded on P balance in soils. The changes of P forms in fertilizers aapplied relied on soil properties. The great effect of fertilizer P occurred at the early growth stage of plants. At the middle and late stages, plant took up more soil P. P-fertilizer efficiency in coarse and fine sand soils was 41.1% and 17.7% respectively, higher, than that in light sand soil.

Abstract:The results from a nine years' field experiment on a calsic cinnamon soil indicated that the annual input of P 14.4kg/ha which is a little lower than the phosphorus harvested each year, had not only keeped higher crop yields but also maintained the soil total phosphorus pool and with a little increase of soil organic phosphorus in cultivated layer. In the treatment with nutrinents in 80% of harvested products recycled every year through a feeding-compesting cycle combined with phosphrous fertilizer applied, the crop yields and the soil organic phosphorus content both considerably increased after nine years. There was a significant decrease of soil total phosphorus from the plot receiving nitrogen but no phosphorus fertilizer, a large propotion of phosphorus provided to crops was from soil non-labile phosphorus pool, but only 12% of phosphorus from labile phosphorus pool when the soil is lack of phosphorus. Calculation indicated that about 90% of the P taken up by crops was from soil cultivated layer.

Abstract:An anaerobic bacterium strain isolated from activated sludge showed a strong ecological effect on the degradation of PM residues after inoculation into the PM-polluted soil. The results showed that in the pot experiment, the yellowing degree of rice leaves of bacterium treatment was remarkably slighter than that of control. The PM residues in rice of the bacterium treatment reduced by 82.2-100%. In the field experiment, no PM residues were found in rice of the bacterium treatments. But the PM content of control was over 0.065mg/kg, which exceeded the national standard of 0.05mg/kg.

Abstract:The climate index about the soil zonal distribution of China, R=exp(-0.08T)[1-exp(-0.005P)], is first put forward. Based on the climatic data from 659 observational stations in China, R distributions of a forest soil sequence and a steppe soil sequence are given, and a map of climatic soil zonal distribution in the monsoon region of the eastern part of China is obtained by the climatic index R, which is in general agreement with the Soil Map of China and the Soil Regionalization Map of China. Meanwhile, the directions of soil zonal evolution are analyzed, then a formula for the altitudinal zonal spectrum of a forest soil sequence is derived, which is demonstrated to be in quite well agreement with the actual situation. Finally, a possibility of determining the delay time of soil zonal change with climate change is pointed out.

Abstract:The total Se contents of soils in Guizhou Province range from 0.064mg/kg to 1.326mg/kg, with an average of 0.369mg/kg, tending to increase as the terrian decends from north to south east. The whole province can be divided into four Se regions: (1) the region of low Se content; (2) the region of medium-low Se content; (3) the region of medium Se content; and (4) the region of medium-high Se content. In general, most of the soils in Guizhou have a medium Se level, and only a small part belong to Se-rich soils. Besides, there exists some distribution of low Se content soils in Guizhou province.

Abstract:This paper briefly introduces the nature conditions, salinization and current amelioration situation of alkalized soils in the Hetao irrigation district, Nei Mongol. Formation, properties and characteristics of the alkalized soil in the district are revealed in the paper Formation of alkalized soils in the district are summarized as follows: 1. Most of the seriously alkalized soils in the district were formed due to large quantity of residual sodium carbonate and intense evaporation of ground water under arid climatic conditions, being characterized by high degree of alkalization of whole soil profile. 2. Sodium ions contained in ground and surface water were concentrated by absorbing complexs in the soils under the influences of various factors. The soil surface are commonly found with a high degree of alkalization. 3. Some low-lying land soils were alkalized as a result of biological actions.

Abstract:The investigation on the salt tolerance of potato grown on sand dunes and its management with saline water drip irrigation was carried out in the Negev Experimental Station for Saline Water Irrigation from Feb. to Jul. 1993. Potatoes were irrigated with ECw 1.2 dS/m (National Water Carrier) and ECw 6.2 dS/m (Local Well) water at three frequencies: 1 time/day, 3 times/day, and 6 times/day. A series of physiological and growing determination and salt accumulation measurement of the soil under drip irrigation were conducted during the trial. It was found that saline water irrigation reduced potato production by 12% compared with fresh water irrigation at the frequency of 1 time/day, while there were no significant differences between saline and fresh water irrigation at frequencies of 3 times/day and 6 times/day. However, saline water increased tuber weight and dry weight ratio. Plant height, growth and dry matter accumulation of potatoes decreased in case of saline water irrigation. Potatoes of high yield and quality can be produced on sand dunes only by adequate irrigation. We believed that the high permeability of sandy soli could allow the use of saline water with drip irrigation, thus, the natural resources (water and nutrients) can be controlled for the requirement of plant growth.

Abstract:In this paper, the research work concerning the resources, structure, composition and nutritional functions of organic fertilizer,and the mechanisms of organic fertilizers in improving soil fertility and enhancing the quality of crop products, done in China since 1986 are reviewed. The relationship between the combined application of organic fertilizers with chemical fertilizers and the development of sustainable agriculture and the establishment of optimum environmental ecology are discussed. The perspective of future research on organic fertilizers should be the utilization of organic fertilizer resources as much as possible, put them into agricultural fields and let them join in the nutrients recycling in agricultural system. The cycling and re-utilization of carbon, potassium, and micronutrients would be the major research targets of cycling of organic fertilizers, so as to protect environmental quality and improve nutrient balance in food chain as well as agroecological system.

Abstract:作物幼苗期的供肥状况,对以后的生长发育将产生重要影响。肥料型种子包被是播种前种子处理的一种方法^[1],将少量的速效性肥料包裹在种子外层,为作物幼苗早期提供所需要的养分,有利于培育壮苗,增强幼苗的抗逆能力和与杂草的竞争能力。

Abstract:本文是依据油菜不同生育期缺氮缺磷水培试验和氮、磷肥施用量(两因素五水平不完全设计¹⁾)田间试验的资料拟写而成的,旨在揭示油菜氮、磷缺素症状的特征及其含量变化与产量的关系;建立氮、磷营养回归方程,提高营养化学诊断的定量度和精度以及诊断水平;借助施肥数学模型,以“插值法”取代“误差检验法”分析精确施肥量指导施肥,达到提高产量,节省肥源,减少污染,降低成本,增加收人的目的。

Abstract:暖温带黑粘土是我国变性土纲的一个主要类型,在淮北平原、南阳盆地、山东胶莱平原和苏北平原均有较大面积的分布。黑粘土虽然有机质含量一般,但土壤颜色深暗,在耕层之下,有一棱柱状结构的残留黑土层,色调尤深。同时,黑粘土土壤肥力较低,是一种急待改良的土壤。黑粘土的这些特点,与其有机质的特性不无关系。本文就该种十壤的腐殖质组成、胡敏酸的光密度指数及其沿剖面的分异特征进行了分析,发现了一些特点和规律。并对其暗色的成因、剖面分异原因以及腐殖质特性与卜壤肥力的关系等进行了探讨。