Study On Properties Of Water And Nutrient Conservation Of Peat And Effects Of Different Amended Models On Root-Zone Of Grape

The conflicts between population and food and between resource and environment in the World are becoming sharper. How to improve water and fertilizer using efficiency was an important research task of the agricultural sustainable development in China. It was a key research for horticulturists to study on root-zone environment of fruit tree and soil improvement of orchard. Investigations showed that properly irrigating and fertilizing in partial root-zone could offer plant growth. "Theory of nutrition center", "Local supply"and "Handy supply"were rules which come into being at plant growth process. In order to solve the problems of drought and poverty, saving water and fertilizer was significant for the sustainable development of fruit tree produce. Peat had many properties, including deducing bulk density, increasing porosity and holding water and fertilizer. Peat resource in China was very abundance, and price was low. There are many reports about peat in foreign countries. But researches on hydro-physical properties of peat were infrequent in China. Researches about properties of preserving fertilizer were limited to some qualitative dissertates. In research of soil amendments using peat, a lot of them were the mixed style, which was a kind of the waste of resource. Some researches showed that using peat in a concentrated way could improve its using efficiency, but these studies were very scarce. Therefore, studies on the characters of water and nutrient retention of peat and its using styles had significance on extensive application in horticulture and environmental protection. This experiments systemically and extensively researched the properties of water and nutrient conservation of peat,sandy soil and loamy soil. At the same time, the living environment of root system was locally amended in a centralized way. Adjusting and using "Theory of nutrition center", "Locally supply", properties of water and nutrient conservation of different amended styles and their effects on grape growth were generally and systemically studied. The main results were as follows. 1. Water character curve of peat, sandy soil and loamy soil were comparatively studied. Fitting equations of 3 kinds of soil were obtained. Farther, sandy soil was amended by peat, their hydro physical properties were deeply discussed. Under the same pressure, water content of peat was higher than sandy soil's and loamy soil's. van Genuchte and Zhang—van Genuchten models could preferably describe water character curve of 3 kinds of soil. Brooks-Corey could commendably describe sandy soil's and loamy soil's, but could inaptly describe peat's. Utilizing low-humified sphagnum peat to amend sandy soil, the total porosity, field capacity, saturated capacity was increased, and water retention of the medium was improved. The degree of medium shrinkage was increasing with peat content in media. Irrigation frequency had effect on the evaporation and water potential of different medium. The higher the peat content was, the higher the mean daily evaporation was from the medium surface, along with the increase of irrigation frequency. Using infrequently irrigation,the pure peat retained the more available water for the plant growth. 2. The absorption characteristics of NPK were studied under constant temperature condition, by selecting peat, sandy soil, loamy soil and the mixed soil as experimental material. Meanwhile, the optimal model was selected to fit the adsorption isotherms, adsorption and desorption kinetics. Results showed that conserving ability of peat to N and P was significantly higher than others, and conservation to K was insignificant; Freundlich and Temkin model might fit NH4+ adsorption isotherm, Freundlich model might fit K and P adsorption isotherms. By selecting Ca2+-saturated and NH4+-saturated soil, NH4+ adsorption and desorption kinetics, and phosphorus desorption kinetics were studied, and optimal model to fit adsorption and desorption kinetics of different soil was obtained. 3. Under the mixed amendment condition, Logistic model was employed to fit grape growth process; the grey relation degree analysis was used to investigate the relationship of grape growth, peat content and physical properties; the relation between grape root growth and basic properties in different typical soil was analyzed by using path analysis. Meanwhile, the optimal ratio of peat amendment and the optimal physical and chemical properties of soil were obtained. Peat added in soil increased significantly total porosity and physical clay content, and improved water and nutrients conservation of soil. When Logistic model was employed to fit the process of grape growth, it's relative coefficient was above 0.98. According to the Logistic model, the growth process of one-year grape shoot might be divided into three periods, including earlier stage of growth, rapid growth stage and later stage of growth. The results showed that the effect of physical clay content and total porosity on one-year grape shoots was significant; the effect of special gravity was insignificant. In different treatments, 15% peat added in soil might improve root growth of grape significantly. Path analysis was used to investigate the relationship between growth of root and soil basic properties which involved bulk density, total porosity, physical clay content, total phosphorus, total potassiumand organic matter, and results showed that total porosity, physical clay content, total nitrogen, total phosphor, total potassium and organic matter were primary factors which effected on different typical root growth. At last, the bridge regression was employed to build correlative mathematic equation, and the optimal ratios of peat amendment in sandy and loamy soil were respectively 8.8 and 12.1 percentage. 4. Peat was applied to root-zone in layered style. Effects of localized amendment on the grape growth were studied in detail. The results showed that localized treatments of peat accelerated the grape growth, and effects of 7.5% and 15% were best in all treatments. For example, height, diameter, node length, chlorophyll contents and photosynthesis rate of grape shoot, root activity and dry weight increased all. Effects on root dry weight in every soil layers were significant, root density and root activity in peat layer were significantly higher than one in no peat layer, and root activity was still keeping high in growth latter phase. Growth of grape was restrained under the insufficient irrigation, but making use of peat could reduce the damage of drought. Applying urea increased total weight, chlorophyll contents, photosynthesis rate, transpiration, deduced root/shoot, and improved efficiently root activity, and can retain long-playing activity in peat layers. 5 we studied characters of holding water and fertilizer of two kinds of amended style and their effects on grape growth. Results showed that the effect of localized amendment was optimal, and its biologic effects were very significant. Peat added in soils increased capacity of water and nutrients conservation of reconstituted soils, and efficiently stimulated the grape growth. Soil amendment increased total biomass, the concentration of chlorophyII, photosynthesis, transpiration, root dry weight, root activity, and ZA,IAA and GA content, and reduced ABA content. The capacity of holding water and fertilizer and biologic effects on grape growth of localized amendment were more significant than the mixed amendment. Length per vine,daily elongation rate were higher after bud break 50-60 d. Total masses of the localized amendment in sandy soil were higher 145 % and 40 % than the control and the mixed amendment respectively. Its leaf photosynthesis, transpiration, and chlorophyII concentration were higher than the mixed amendment and the control. The localized amendment improved root activity and dry weight, and promoted effectively the balanced growth of root and shoot.