Spatio-temporal Distribution Of Physical And Chemical Properties Of The Purple Soil Surface With Perturbations On Different Slope Lengths

With the continuous development of social economy, the projects about agriculture, forestry, municipal engineering are everywhere. Increase the destruction of the earth’s surface and intensity of erosion on the soil surface. Artificial surface disturbance will cause loose bare soil surface and exacerbate soil erosion. Slope length is an important factor of affecting soil erosion, slope length factor research on prevention of soil erosion is important. In order to explore artificial disturbance surface in different slope lengths to the influence of soil physical and chemical properties in purple soil area, set 20,40,60 m three runoff plots and weed regularly in manual and set the corresponding natural slope length as a control measure. By determining soil physical and chemical properties in from 2013 to 2015 rainy season on each slope length. Analysis of artificial disturbance surface under different slope length effects on soil properties, and evaluate the influence of soil quality in the disturbance of surface and the slope length factor. Provide reference for the future of projects about agriculture, forestry municipal engineering to disturbance on the surface of the soil properties. Research indicates:(1) Changes of soil nutrients were obvious in 2013 to 2015, the soil nutrients in the natural slope were greater than the disturbed surface, below the surface. In 2015, with the increase of slope length the soil organic matter were gradually increasing, rule: 60> 40> 20 m, and with the change of slope length, the rangeability of soil organic matter was greater. With the change of years, soil organic matter was a growing state. Soil total nitrogen in the natural slope was greater than the disturbed surface, total nitrogen content of soil in disturbance surface was no significant difference, the rule of total nitrogen content in soil slope length was 2014> 2015> 2013. In 2015, soil available nitrogen in the same process increased with the slope length increasing.(2) Soil total phosphorus in 2015 was between 0.37-0.42 g / kg and trend was not obvious. Over time, in addition to 20, 60 m of surface disturbance measures, soil total phosphorus content was declining in other treatments in the test area. In 2015, changes in the magnitude of the disturbance surface soil available phosphorus content in soil was greater than the natural slope. In from 2013 to 2015, soil total potassium content under the surface disturbance was less than the natural slope length. In 2015, soil phosphorus content under the surface disturbance was higher than the natural slope length, the slope was longer,the difference was obvious. Soil total potassium content in 2014 was lower than 2013 and 2015. Soil available potassium in natural slope was higher than the disturbance of soil under the surface.(3) In from 2013 to 2015, the overall variation of soil bulk density was 2013 <2014 <2015. Under the same treatment the rule to soil bulk density was 20> 40> 60 m and the longer slope length, soil bulk density decreased. The rule of total soil porosity was 2013> 2014> 2015, with the change time the total soil porosity was reduced. The rule of soil capillary porosity was 2014> 2013> 2015. In from 2013 to 2015, non-capillary porosity in the natural slope length was higher than the surface under 20,40 m long slope of soil disturbance. In 2015, the maximum retention of soil water storage with increasing slope length increased. In from 2013 to 2015, maximum retention pondage and saturated soil pondage changes over time maximum retention pondage and saturated soil pondage gradually reduced.(4) In 2014, the soil infiltration curve steep dropped by a big margin, in 2013 and 2015 soil infiltration curve was less magnitude. In from 2013 to 2015, each infiltration rate changed over time and gradually reduced. Through the soil infiltration process simulation, Horton equation model fitted best, Kostiakov equation model fitted less, and Philip equation model fitted worst. Correlation analysis showed that soil organic matter, soil bulk density, soil initial water content, non-capillary porosity and total porosity were the main indicators of the impact of soil infiltration capability.(5) Soil particle-size distribution in the dominant aggregates was 0.05-0.25 mm, the content was 33.21-22.55%. Soil micro-aggregates in the dominant aggregates was 0.05-0.25 mm, a secondary advantage was 0.05-0.01 mm. The fractal dimension under disturbance surface was less than the fractal dimension under natural slope length, slope length was longer, the fractal dimension was higher. Soil nutrient content of the longer slope length was higher : 60> 40> 20 m, soil nutrients under disturbance surface were less than soil nutrients under natural slope length in three slope length. Positive correlation between soil fractal dimension with the soil bulk density was significant(P<0.01), with soil total nutrient was significantly associated(P<0.01), the dimension of soil fractal under disturbance surface with soil porosity were significant or very significantly correlated(P<0.01 or P<0.05). The fractal dimension of soil micro-aggregate and particle-size distribution can better reflect physical and chemical structure of soil in the purple soil area and more intuitively reflect the changing of soil structure and physical and chemical properties after the disturbance, prove a scientific basis which is soil quality evaluation and Agricultural Assessment in purple soil area.(6) Through the soil physical and chemical properties correlation analysis showed that total nitrogen and nitrogen and potassium were significantly correlated(P<0.01), nitrogen with potassium was significantly correlated(P<0.01), among other chemical indicators did not reach significant correlation. Soil air permeability majorly impacted on soil physical indicators about soil bulk density, porosity and initial water content and so on. Principal component analysis method to comprehensive evaluation of soil quality: With the change of the year, a downward trend in soil quality. In 2013 ~ 2015 under the natural slope length of soil quality are better than disturbance under the surface of the soil quality. Soil quality was increased under the same process with increasing slope length, illustrating the longer slope length, the better soil quality.