Study On Soil Erosion And Soil Fertility Under Typical Land Use In Hilly Red Soil Region Of South Jiangxi

In recent years,the ecological environment effect caused by land use change have attracted much attention.This paper takes Nanfeng County-the hometown of Chinese tangerines-as the research area,and selects a small watershed in Danyang Village,Taihe Town,southeast of Nanfeng County as the sampling area.Based on the high-resolution remote sensing images of 2003 and 2016,combined with geo-statistics,the temporal and spatial variation characteristics of land use in Taihe town in the past 14 years were analyzed.The paddy fields,orange orchards,rice field orange orchards?orange gardens transformed from paddy fields?,artificial fir forests,wetland pine forests,shrubs,bamboo forests,and navel orange orchards were selected as sample plots in the sampling area.The characteristics of soil erosion and soil fertility change under eight land use patterns were studied,and the effects of soil erosion on soil nutrient loss and soil comprehensive fertility were discussed,in order to provide theoretical basis for land use management and ecological restoration in the region.The main conclusions are as follows:?1?From 2003 to 2016,because of the brand effect of Nanfeng orange and the driving force of economic benefits,the planting areas of orange orchard in Taihe town was rapidly expanding,mainly manifested in the conversion of forest and farmland to orange orchard,and the increasing area of orange orchard has already reached 57.25km².Meanwhile,during the period of research,the water body of Taihe town has significantly increased,because the study area is also a famous turtle town in China,and the turtle breeding scale is large.With the study time period,4.759km² of farmland was converted into turtle breeding base.In addition,with the rapid urbanization,the area of urban and rural residential areas and industrial and mining land in Taihe town also showed a significant increase trend.?2?In different land use,slash pine forest,bamboo forest,shrub forest,navel orange orchard and orange orchard are all affected by erosion.The order of erosion modulus from large to small is:slash pine forest>bamboo forest>shrub forest>navel orange orchard>orange orchard.Paddy fields and orange orchard in paddy fields are affected by sedimentation because they are located in valleys of the small watershed,and artificial fir forests are also affected by sedimentation because of their cascade planting patterns and high canopy density.On the whole,the erosion of cultivated land is small or deposited,while the non-cultivated land is large.The land use patterns of four kinds of sloping land in orange orchard,artificial fir forest,slash pine forest and bamboo forest all showed serious erosion on the uphill slope,and the erosion on the lower slope was small or affected by sedimentation.The results showed that the sediment will be collected from high to low with the flow of water.?3?The order of soil fertility index under different land use patterns was paddy field>paddy field orange orchard>artificial fir forest>Orange Orchard>slash pine forest>bamboo forest>navel orange orchard>shrub forest.Generally speaking,the soil fertility index of cultivated land is larger than non-cultivated land.Among the four types of slope land use patterns of orange orchard,artificial fir forest,slash pine forest and bamboo forest,Soil organic matter,total nitrogen,alkali-hydrolyzed nitrogen,available phosphorus,available potassium and comprehensive soil fertility index of slash pine forests and bamboo forest were affected by runoff erosion at different slope positions,showing a trend of convergence at downhill positions.The nutrients of orange orchard and artificial fir forests were affected by cascade planting pattern and artificial fertilization.There is no obvious tendency for elements to converge downhill.?4?The correlation analysis showed that there was a significant difference in the correlation between ¹³⁷Cs and nutrient elements in cultivated land and non-cultivated land in small watershed sloping land.The effect of artificial fertilization on nutrient elements in cultivated land was not correlated with ¹³⁷Cs,while ¹³⁷Cs in non-arable land was significantly correlated with soil total nitrogen,alkali-hydrolyzed nitrogen,available phosphorus and organic matter.In addition,¹³⁷Cs in valley soil of small watershed was correlated with organic matter,total nitrogen,alkali-hydrolyzed nitrogen,organic matter,available phosphorus and pH;¹³⁷Cs tracer soil erosion was significantly positively correlated with soil comprehensive fertility index.The results showedthat soil comprehensive fertility quality in the study area was affected by soil erosion,and the aggravation of soil erosion would cause the degradation of soil fertility quality.