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Effect of Water Dynamic Process and Strength on Nutrient Availability in Loess Plateau

Author: ZhuYongLi
Tutor: WangYiQuan；LiuJun
School: Northwest University of Science and Technology
Course: Soil
Keywords: Water Potassium Chloride ion Partition coefficient Diffusion coefficient
CLC: S152
Type: Master's thesis
Year: 2002
Downloads: 294
Quote: 5
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Abstract

Loess Plateau is dry, the humidity of the complex and ever-changing weather conditions led to a certain depth in the soil surface in the area time and space changes very dramatic; Moreover, the structural and pore continuity of the soil in the area is relatively poor, hard to reach the surface of the deep soil moisture, making soil surface in a recurring alternate wetting and drying process of change. Complicated and changeable such dynamic changes of soil moisture on nutrient availability has rarely been studied. Therefore, this study by the dynamic changes of the indoor simulated soil moisture, the moisture change process (wet and dry) and changes in the intensity of nutrient availability alternately ongoing, nutrient ions in different water potential state distribution relationship between the solid and liquid discussed, as well as the diffusion of nutrients under different water conditions migration of. Its purpose is to reveal the mechanism of soil moisture and nutrients role relationship further enrich the relationship between water and fertilizer coupling theory, improve the utilization of soil water and nutrient resources provide a theoretical basis for scientific fertilization. The results are as follows: 1. Water characteristic curves of the four major agricultural soils in the Loess Plateau, there is no clear platform or inflection point, its relationship with the Garden empirical equation (W = AS ^{-B ) were fitted. Thus proving that the soil structure of the area is not very obvious. Water-holding porosity is mainly affected by soil texture traits significant impact. 2. Soil moisture dynamic process (number of alternating wet and dry), and changes in intensity (temperature change) the effectiveness of four types of soil potassium in the Loess Plateau. In the case of potassium content of 200mg/kg, alternating wet and dry impact on the validity of the four kinds of soil potassium in descending order: Lou soil, black loam, loess soil, wind sand. With the increase in the number of alternate wetting and drying, a fixed amount of soil potassium increases, the rate of increase gradually stabilized. Alternate wetting and drying has y = a blogx functional relationship between the number of available potassium. Elevated temperatures, to enhance the intensity of the alternating wet and dry, to significantly increase the soil a fixed amount of potassium, and reduces the effectiveness of the potassium fertilizer. And in accordance with the the soil basic traits and soil K fixation capacity equation to reflect the number of alternate wetting and drying, the relationship among fixed amount of the soil physical clay and clay content ratio of potassium. The experiment shows that the potash deep application to the more stable soil moisture in the soil is very necessary. 3. Different water content (or water suction) under the conditions of the distribution ratio of potassium ions in the solid-liquid and white, is caused by ions migrate at different rates in different water conditions the root cause. With the increase of water suction, the decline in the ratio of the solid phase of potassium ions (Cs), the liquid potassium ion ratio is gradually increased, and the distribution coefficient K decreases. In the the water suction approximately 1.5 × 10 ^{5 PA four soil potassium ions in the distribution of the solid-liquid interphase reaches the stable, the distribution coefficient is minimum. Soil texture, different variations of the amount of solid and liquid ion. Lighter texture than the sand soil fluctuated, sticky texture of the soil is relatively small. K and soil organic matter, CEC, clay content, clay content of the physical, as well as the basis of soil samples effective potassium content basically was a significant correlation between. Also exist in the soil dryness obvious potassium invalid phenomenon. This is further evidence that any dehydration cases K ^{is fixed may have. 4. Under conditions of no flow of water, over time, the nutrient ions (Cl ^{- and K ^{, ) diffusion peak only in the concentration gradient of the role by the soil surface to the lower layer significantly movement. Available semi-logarithmic equation * II a + bLnz) fits two from the dynamic process of diffusion in the soil profile, where C is the raising separated from content the Qin pair g) / the soil depth Ren), c, b intended aggregate parameter. 5.25C, a non-saturated conditions, four soil O, defined diffusion coefficients increase with the water content increases, the former increased linearly with the water content, which increases exponentially increased or the power function. With the extension of the diffusion time, the chloride ion diffusion is significantly faster than the potassium ion. 6. The semi logarithmic equation (f = a + bLnW) is the best relationship fit the soil the tortuous coefficient even) with water content (W%). 7. Potassium, chloride ion diffusion coefficient and soil Yang ion exchange amount (CEC), the physical clay and clay content was a significant negative correlation or positive correlation. This fully proves that the soil texture, and * a justice electrical differences affect ion mobility status of one of the main reasons for BU described conclusion is further proof of the water status of various from the diffusion migration, and its effectiveness. The dramatic changes of soil moisture are also important factors that affect the maintenance separation effectiveness. The nutrient moderately deep application to a certain humidity level, and the humidity is relatively stable soil, is one of the measures to improve the efficiency of nutrient utilization in arid regions.}}}}}

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