| Soil erosion is an important ecological and environmental problem.Soil erosion will destroy land structure,reduce soil fertility and lead to the decline of agricultural productivity.At present,the research on soil erosion is mainly divided into two directions:macro-calculus and indoor simulation.However,little research has been done on the morphological characteristics of soil erosion on the scale of land blocks.Especially after land consolidation,the soil quality of newly-added cultivated land is relatively loose,and soil erosion is more likely to occur under the action of rainfall.By studying the soil erosion of new cultivated land and preventing soil erosion,we can effectively protect regional ecological security and promote regional development.Tangxian County is located in the key control area of soil and water loss in Taihang Mountains.It is mainly affected by hydraulic erosion.At the same time,a large number of unused land in Tangxian County has been developed into arable land.The soil texture of newly-added arable land is relatively loose,and soil erosion is very easy to occur.Therefore,this paper takes Baishan Village Development Zone,a typical development area in Tangxian County,as the research area,and takes the newly-added cultivated land as the research object,combines field investigation and indoor analysis to study the variation law of soil erosion intensity and morphological characteristics of newly-added cultivated land,and analyses the physical and chemical properties of newly-added cultivated land in different topographic and erosion areas,with the aim of rationalizing the unused land.Development,prevention and control of soil erosion and protection of regional ecological environment provide a theoretical basis.The main research results are as follows:?1?The soil erosion modulus of new cultivated land reached 9683.76 t?km-2,and the erosion modulus of new cultivated land in valleys and ridges were 11999.77 t?km-2,8114.98 t?km-2,respectively.The channel density was 0.05 m?m-2 and 0.03 m?m-2,and the channel splitting degree was 0.03 and 0.13,respectively.The erosion intensity of newly-added cultivated land decreases gradually with the decrease of field surface,which shows a wave-like trend of first decreasing,then strengthening and then decreasing.In the first stage,the field surface is directly subjected to upper water flow and rainfall erosion,and the soil erosion degree is larger,but it has played a certain role of storage.The soil erosion degree decreases gradually with the decrease of field surface.With the concentration of soil and water,the water impact ability gradually exceeds that of the second stage field.With the limit of surface storage capacity,soil erosion increases again,and so on,with the terrace field from high to low,the erosion intensity shows a wave erosion state that first decreases and then increases,then decreases and then enhances.?2?Under the condition of no-tillage,the physical properties of the newly-added cultivated land in the study area changed greatly compared with the soil source.The field water holding capacity,total soil porosity and non-capillary porosity of the newly-added cultivated land decreased,the soil bulk density increased,the capillary porosity of the soil was basically the same as that of the soil source,and the difference between the valley and the ridge was not obvious.The size of soil aggregates in dry-screening of newly-added cultivated land mainly distributes in two grades of particle size>5 mm and<0.25 mm.The order of soil resistance to runoff erosion and mechanical damage is as follows:new cultivated land in valley area>new cultivated land in ridge area>soil source.The soil mechanical composition and soil aggregation structure of new cultivated land in different topographic areas changed greatly under the action of soil erosion.The loss of fine sand and coarse silt in new cultivated land was significant?P<0.05?.The content of fine sand and coarse silt in ridge area decreased by 3.64%and 2.00%respectively compared with that of soil source.The content of fine sand and coarse silt in valley area decreased by5.41%and 5.99%respectively compared with that of soil source,and the content of fine sand and coarse silt in valley area decreased by 5.41%and 5.99%respectively.Under the condition of dry screening,the content of soil aggregates with diameter less than 0.25 mm was significantly lower than that of soil sources?P<0.05?,and the content of soil aggregates with diameter less than 0.25 mm was significantly lower than that of new cultivated land in valleys and ridges,respectively,28.92%and 11.84%.Under the condition of wet screening,the content of soil water-stable aggregates with diameter less than 0.25 mm was significantly lower than that of soil sources?P<0.05?,valleys and mountains.The ridge area decreased by 10.97%and 3.40%respectively.?3?Under the action of soil erosion,the soil nutrient content of newly-added arable land in the study area changed greatly compared with the soil source.The soil pH value and total nitrogen content were basically the same as the soil source,the soil organic matter and available potassium content were increased,and the soil available phosphorus content was decreased.The organic matter content of surface soil in valley increased 12.10 g?kg-1,deep soil increased 12.53 g?kg-1,surface soil organic matter content in ridge increased 9.24g?kg-1,deep soil increased 12.10 g?kg-1,available potassium content in surface soil in valley increased 25.96 mg?kg-1,deep soil increased 11.26 mg?kg-1,and available potassium content in ridge soil increased 9.24 g?kg-1,respectively.The available phosphorus content in the surface soil of the newly-added cultivated land valley increased by 4.51 mg?kg-1compared with that of the soil source,the available phosphorus content in the deep soil decreased by 2.89 mg?kg-1,the available phosphorus content in the surface soil of the ridge decreased by 1.92 mg?kg-1 compared with that of the soil source,and the deep soil decreased by 4.58 mg?kg-1.?4?The field water holding capacity,total porosity,capillary porosity and non-capillary porosity of newly-added cultivated land in non-erosion area decreased by3.22%,8.04%,0.97%and 7.07%respectively,while the soil bulk density increased by0.21 g?cm-3 compared with the soil source.Soil bulk density is non-erosion area>sedimentary area>gully erosion area,total soil porosity is gully erosion area>sedimentary area>non-erosion area,which is consistent with the size of capillary porosity,while non-capillary soil porosity is non-erosion area>sedimentary area>gully erosion area.Soil nutrients in non-eroded area increased in varying degrees compared with those in guest soil.Organic matter,total nitrogen,available phosphorus and available potassium increased by 235.13%,15.64%,21.97%and 49.73%respectively compared with guest soil,and pH changed slightly before and after land development.The contents of organic matter,available potassium and total nitrogen in different eroded areas were as follows:non-eroded area>sedimentary area>gully erosion area,and available phosphorus.In summary,from the point of view of erosion intensity and morphological characteristics,the regularity of soil erosion morphological characteristics of newly-added cultivated land is analyzed.At the same time,the influence of soil erosion on soil physical and chemical properties is analyzed from two angles of different topographic and erosion sites,which has important reference value for guiding the prevention and control of soil and water loss of newly-added cultivated land. |
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