Effects Of Barren Grassland Development On Soilphysical And Chemical Properties And Water Conservation Ability In Tangxian Of Hebei Province

In order to alleviate the contradiction between people and land caused by the rapid development of industrialization and urbanization,China has carried out large-scale unutilized land development and arrangement in an orderly manner in the late 1990s.Barren grassland is the main source of arable land reserve resources,which accounts for a large proportion of unused land development and had better soil quality.The development and utilization of barren grassland has increased the area of effective cultivated land,which plays an important role in realizing the balance between the occupation and compensation of cultivated land and ensuring food security.The large-scale development of barren grassland has changed the soil site conditions and land use patterns,thus affecting the physical and chemical properties,fertility status and ecological functions of the soil.Soil physical and chemical properties,especially soil bulk density,aggregates,porosity,water content,nutrients and soil water conservation ability,are important indicators to measure the quality of newly cultivated soil.Land use patterns and utilization years are the key factors affecting these soil physical and chemical indicators and soil functions.Therefore,this paper takes the development of barren grassland in hilly and mountainous areas of Tangxian County,Hebei Province as the research object.Through field investigation and laboratory experiment on cultivated land with different utilization modes and different utilization years after its development,the paper discusses the influence and the change characteristics of different land utilization modes and different utilization years on the physical and chemical properties of barren grassland in this region.This paper establishes the quantitative relationship between soil physical and chemical properties and water conservation ability,evaluates soil water conservation ability comprehensively,and provides scientific suggestions for further improvement,rational development and utilization of land and efficient soil management.The main research conclusions are as follows:1.The study of soil physical and chemical properties under different utilization modes showed that the soil total porosity,capillary porosity,saturated water content,capillary water holding ability and field water holding ability of 0-10 cm cultivated land were the largest,and the physical properties of cultivated land soil were better than those of forest land and garden land.The soil aggregates,total porosity,non-capillary pore,saturated water content and field water holding ability of the 10-20 and 20-40 cm garden plots were the largest,and the physical properties of the garden soil were better than that of the forest land and the cultivated land.There was no significant difference in pH change under different utilization methods from 0 to 40 cm,and soil nutrient content decreased with the deepening of soil depth.The organic matter and total nitrogen content of forest land were higher than those of garden land and arable land,and the available potassium and phosphorus contents of arable land were higher than those in the garden land and forest land.2.The comprehensive ability of soil water conservation under different utilization modes showed that soil water storage ability was positively correlated with total soil porosity,saturated water content and field moisture ability,whereas it was negatively correlated with soil bulk density.Soil saturated water content,total porosity and non-capillary porosity were the key indicators affecting water conservation ability.The order of soil effective water storage ability was garden land>forest land>cultivated land,garden land was increased by 203.54 t/hm~2 and 240.49 t/hm~2,compared with arable land and woodland,respectively.The comprehensive ability of soil water conservation was the best in garden land,forest land and arable land.3.The study of soil physical and chemical properties under different utilization years of cultivated land showed that with the increase of utilization years,the total soil porosity,non-capillary porosity,saturated water content,field water holding ability and other physical indicators generally had a trend of decreasing-increasing-decreasing-increasing,while the variation of bulk density was opposite.The contents of organic matter and total nitrogen gradually increased with the increasing of the utilization years.The variations of available phosphorus and potassium in different utilization years were not obvious.4.The comprehensive ability of soil water conservation under different utilization years of cultivated land showed that soil water storage ability was positively correlated with total soil porosity,saturated water content and field moisture ability,whereas it was negatively correlated with soil bulk density.Soil saturated water content,total porosity,non-capillary porosity and field moisture ability were the key indicators affecting water conservation ability.Soil effective water storage ability was the largest in the 20th year and the smallest in the 3rd year.The maximum annual change range of effective storage ability in the third year was-18.96%,and the minimum was 1.15%in the 10th year.After the third year of utilization,it increased with the increasing of the number of years,and after the 10th year of utilization,the change range became small,gradually reaching a stable state.The comprehensive ability of soil water conservation was 20 years>15 years>10years>5 years>1 year>3 years.The comprehensive ability of soil water conservation was the lowest in the third year of utilization and the highest in the 20th year.In summary,this study revealed the changing rules of soil physical and chemical properties such as soil porosity,bulk density and saturated water content from the two perspectives of different utilization modes and different utilization years of cultivated land,and comprehensively evaluated the comprehensive ability of soil water conservation,and provided scientific basis for the development and consolidation of wasteland,the protection of cultivated land,ecological restoration and sustainable development.