Abstract:The characteristies of K⁺ adsorbing-desorbing kinetics of five loessial soils were studied by the liquid flow technique. The results indicated that:①K⁺ adsorption and desorption equilibrated in 16-24 and 24-60 min, respectively, and the time and the capacity of K⁺ equilibrium adsorption were closely related with soil clay content and CEC;②there was a linear relationship between the K⁺ adsorbing-desorbing velocity and the reaction time lnt, and the slop of reaction velocity regression equation and K⁺ desorbing percentage regression equation, the original reaction velocity and the original desorbing percentage were closely related with soil clay and CEC;③First-order and Elovich equations were the best modles for K⁺ adsorption and desorption, respectively;④it is demonstrated that there were dif ferent energy level sites of K⁺ adsorption at the surface of soil colloid by the fast, medium and slow reactions of K⁺ adsorbing-desorbing;and ⑤the K⁺ adsorption and desorption were controlled by the diffussion process.

Abstract:Adsorption of phosphate by different types of soils with variable charge and the changes of negative and positive charges of soil after phosphate adsorption as well as the effect of pH and free iron oxides on the changes of soils were studied. The resalts showed that phosphate was all adsorbed by soils when a smaller amount phosphate was added, and the amount of phosphate adsorbed accounted for 40-85% of phophate added. Phosphate adsorption by soils was closely related with free iron oxides in soils.The positive charge decreased but negative charge increased after phosphate adsorption by soils. The increment and decrement of charges were larger at lower phosphate adsorption. The charges of soils have a parabola relation with phosphate adsorbed. The contribution of phosphate adsorbed to net negative charge of soils ranged between 0.3-1.0 mole per mole phosphate, being the smallest in latosol and the largest in yellow soil.The increment of negative charge of latosol after phosphate adsorption was lower at low pH, but increased with pH increase. For red soil and yellow soil, increment of negative charge after phosphate adsorption was not affected obviously by pH value, The free iron oxides in soils caused a decreased contribution of phosphate adsorbed to negative charge of soils.

Abstract:To efficiently improve planosols in Sanjiang Plain in the northeastern part of China, the physical chemical properties of planosols have been investigated since 1986. The results showed that the AW layer, about 18-40cm in depth, was the key problem in planosol. In the subsoil layer, the water regime is poor with only 5.39% available water. The soil permeability is only 6.08×10^-5cm/s in saturation. Meanwhile, the soil hardness in over 25kg/cm². Because the Aw layer is so close to the surface soil that many problems occur in the ploughing layer, such as shallow available soil layer for crop roots, heavy water logging and drought. When this layer was ploughed into surface soil, the mixed soil could became harder and tighter than before. Nearly 65% of total phosphorus was observed to be organic phosphorus in Ap layer and the contents of p fractions are in the order: Fe-P > Al-P > Ca-P. During the soil incubation, 50%-60%, 10%-20% and 2%-10% of the applied p were changed into Ca-P, Al-P and Fe-P, respectively. According to above-mentioned results, emphasis of the soil improvement should be placed on the Aw layer.

Abstract:Through a 15-year field monitoring location experiment, the nutrients supplying characteristics of yellow fluvo-aquic soil and their changes in the different fertilization systems were studied. The results indicated that fertilizer structure affected greatly crop yields. Under the rotation system of wheat and maize, the average yields of various treatments were in the order of MNPK > MNP > MN > NPK > NP > N > M > CK. The soil without application of fertilizer in the long-term rotation was poor in the nutrients supplying ability, thus resulting in the decreasing of crop yields year by year. The contribution rate of soil basic fertility and fertilizers to crop yields arveraged 37.2% and 62.8%, respectively. In the contribution of fertilizers to crop yield, 25.2% was attributed to organic manure and 74.8% to chemical fertilizers in which N, P and K fertilizers accounted for 64.6%, 27.2% and 8.2%, respectively. Organic manure played an important role in improving soil fertility, improved the soil physical properties and enhanced the adverse resistance and steady high yields of crops. The soil available K deficiency appeared in all of the fertilization treatments. So, attention must be paid to the applying of potash fertilizer so as to maintain potassium balance in the soil.

Abstract:By means of ¹⁵N tracer technigue, the nitrogen absorption of wheat in different ways of soil fertility improvement was studied in purple soils of the Sichuan Basin. The results indicated that the utilization rates of different treatments were in the order of ordinary cultivation with surface layer fertilization (the fertilization depth of 1-2cm) >cultivation by gathering soil with deep layer fertilization (45cm) >cultivation by gathering soil with subsurface layer fertilization (25cm) >cultivation by gathering soil with surface layer fertilization(1-2cm), in which the most high rate was up to 23.78%, and 38.7-44.1% of nitrogen during wheat growth came from nitrogen fertilizer. Before wheat jointing stage. NDFF values of wheat above ground in the treatment of surface layer fertilization were much higher than those in the treatments of subsurface and deep layer fertilization. Some improvement ways including ordinary cultivation with surface layer fertilization and cultivation by gathering soil with deep and subsurface layer fertilization could significantly increase the yield of wheat.

Abstract:The typical and representative purple soils in Sichuan Basin are red purple soil (acidic), gray-brown purple soil Oeutral), and red-brown purple soil (calcareous). The total selenium in the soils ranged from 79.57 to 289.45μg/kg, averaged 212.32μg/kg. The content of selenium was observed to be the highest in the red-brown purple soils and the lowest in the red purple soils. The gray-brown purple soils had a selenium content between the above two soils. Moreover, less difference in the selenium content was found in the red-brown purple soils than in the other two types of purple soils. The distribution of total soil selenium was observed to be similar in the profiles of the three purple soils, being in the order of parent material> cultivated horizon > subsoil horizon > bottom borizon. Higher contents of Ca-Se were found in the calcareous purple soils, while higher contents of Fe-Se in the acidic purple soils. Water soluble Se was very low in the siols, ranged from 1 to 3% of total soil Se. And more than 95% of water-soluble Se existed in the forms of selenate,with only a small part in selenite. A positive correlation (r=0.9835^**) appeared between Se in wheat plants and K₂SO₄-extractable Se in the soils, suggested that K₂SO₄-extractable Se was available for the plants. The degrees of soil factors correlated with K₂SO₄-extractable Se were in the sequence: silt > CaCO₃> organic matter>available Fe > CEC > clay > pH.

Abstract:The temperature effect on water retention curves for four typical soils in Shaanxi Province were studied quantitatively in the work. The results showed that the temperature coefficients of water potential increased with the increase of soil clay content and decreased with the increase of soil water content; there were larger temperature coefficients of water potential in the drying process than in the wetting; in the low temperature range (5℃-20℃),the temperature coefficients of water potential were greater than the high temperature range (20℃-50℃);the hysteresis effect on water retention curves tended to decrease with increasing temperature; for the light texture soils, the effect of temperature on the soil water potential can be explained with the STVF model; for fine-textured soil include the light texture soils), the Gain factor model seemed to perform satisfactorily.

Abstract:This paper deals with the particle fraction, chemical properties, the total chemical composition of fine earth and clay fractions, and the patterns of clay minerals in eight soil profiles on the north slope of Mt. Dabie in Henan Province. The results indicated that the basic belt of soil in the region of Mt. Dabie is that of yellow-brown soils, and the soils sequence going upwards from the mountain foot is in the order of yellow-brown soils→acid brown soils→dark yellow-brown soils→acid brown soils→mountain shrubby meadow soils. According to the Chinese Soil Taxonomic Classification, the soils are indentified and classified.

Abstract:Field and pot experiments were made to study the effect of K nutrition on the morphology, activity and nutrient uptake of rice roots. Results showed that K application based on N and P fertilization can promote the growth of rice roots. The effect of K on root growth was influenced by a number of factors such as the K-supplying potential, kinds of K fertilizer and the K-absorbing characteristics of different cultivars of rice. The strongly K-absorbing cultivar grown on acid soils deficient in K showed the most beneficial effect of K application on root growth. K fertilization increased the amount of roots thinner than 0.2mm in diameter, enhanced the regrowth capability of rice roots, and encouraged the uptake of nutrients such as N, P, K, Ca and Mg, as well as influenced the nutrient distribution in the aerial and underground parts of the plants. As a result of K application, the K concentration in the aerial part increased while the plant root increased, whereas it was reduced in the aerial part of plants grown on Mg-deficient soils. The K-supplying potential in soil had no marked effect on the Ca content in the aerial part and roots of the plant.K application on soils low in K can also encourage the rice root to oxidize α-naphthamine and ferrous ion, thus increasing the activity of the root.

Abstract:Monitoring and predicting technology was studied in the present work. Water and salt movement history in a reclaimed salt soil was obtained by using the method combining field observation with numerical simulation. At the field site, monitored parameters include groundwater table and mineralization, soil salt and water content as well a sevapotranspiration. The numerical simulation was employed for the field conditions. In the work, mobile-immobile water concepts and absorption were taken into account. The results indicated that under the present natural and cultural conditions, soil salt in the test field can be kept balanc dynamically, so that the revival of soil salinization can be avoided.

Abstract:A study was conducted to determine the influence of L-TRP(L-tryptophan) applied to soil on the yield and nurtient uptake of cabbage (Brassica olercea Var. capitata L.)in a pot experiment. The results showed that L-TRP applied to soil a week before transplanting might obviously increase the cabbage yield, dry matter accumulation and the uptake of nitrogen, phosphorus and potassium of cabbage plants, Nitrogen and phosphorus distributed in the head leaves increased but potassium decreased.

Abstract:During 1985-1990 we conducted 4 field experiments on N, P and K to ginseng on solis of Changbai County and Gongzhuling City. All the results showed that nitrogen retarded plant growth and decreased yield of ginseng mostly at 5% sigificance level and even to the level of 1% when the rate of N doubled. By successive study, we found that the nitrate reductase acitvity (NRA) of ginseng was so low that the NO₃ absorded could not be.reduced promptly and was accumulated in the tissues, and that, compared with control, the N, Si, Cu> Zn> Fe and Mn contents incrased in N fertilized ginseng tissues, P and such cations as Ca, Mg, K and Na decreased, and the respiration rate of ginseng shoot accelerated (44.8% over control) by N top dressing. These have ever been described as N toxicity in literature. In this paper we tentatively refer to this physiological toxicity as ‘N excess',which is caused by the fact that the N supply is too much to transfer instantly by low NRA.

Abstract:Study on the eight magnetic parameters including magnetic susceptibility, frequency dependent susceptibility, saturation remanence, etc.) of soils derived from carbonate rock in Guizhou showed that the magnetic properties and changing characteristics of soil were significantly affected by the pedogenic environment and process, and these properties were of important environmental sigificance. On the basis of high-gradient magnetic separation of iron oxide minerals from the soils, systematic studies have been made on the soil magnetic properties and magnetic minerals by using X-ray diffraction, microprobe analysis, transaction electron microscope and Mossbauer spectrum.

Abstract:在盐渍土改良中,碱土与碱化土壤的改良比较困难。国内不少的文献都专门讨论了碱土与碱化土壤的改良,大多为采用石膏、磷石膏结合施用有机肥和翻压绿肥等措施^[1-5]。国外对改良碱化土壤亦有报道,多用化学方法进行改良^[7-10]。1990年美国盐上实验室Rhoades和澳大利亚CSIRO Loveday专门评述碱化土壤(SodicSoil)的改良^[11],指出碱化土壤的改良需加入含钙物质来置换土壤胶体表面吸附的钢或采用加酸或酸性物质的方法改良。