Soil erosion on sloping field has led to a lot of environmental prob lems. In order to reveal the seriousness of the damage of soil erosion on slopin g fields 137Cs tracer method was used to estimate soil erosion rate...Soil erosion on sloping field has led to a lot of environmental prob lems. In order to reveal the seriousness of the damage of soil erosion on slopin g fields 137Cs tracer method was used to estimate soil erosion rate. 137Cs refer ence inventory of 2200Bq/m2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivated soil was established in order t o avoid overestimating soil erosion rates. Then based on the soil erosion rates and measured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further discussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts we re that soil layer became thin, soil structure was deteriorated and soil nutrien ts decreased. The off-site impacts were that water bodies were polluted. The in direct impacts of soil erosion on environment were the increase of fertilizer ap plication and energy consumption, and change of adaptability of land uses. Altho ugh erosion intensity was not serious in the study area, its environmental impac ts should not be ignored because of great soil nutrient loss and coarseness of s oil particles.展开更多
Using data from the farm household survey conducted in 2009,arable land use intensity(ALUI)and its influence factors at farm household level were investigated by the Tobit model.Suyu District of Suqian City and Taixin...Using data from the farm household survey conducted in 2009,arable land use intensity(ALUI)and its influence factors at farm household level were investigated by the Tobit model.Suyu District of Suqian City and Taixing City of Jiansu Province,China were chosen as the regions for comparison.The results show that:1)On the average, the ALUI,labor intensity,yield-increasing input,and labor-saving input are 15 238.14 yuan(RMB)/ha,192 d/ha, 7233.01 yuan/ha,and 2451.32 yuan/ha in the less economically developed Suyu District,and 13 020.65 yuan/ha,181 d/ha,5871.82 yuan/ha,and 2625.97 yuan/ha in more economically developed Taixing City.The figures indicate that Suyu District has higher ALUI and labor intensity input but lower labor-saving input.2)Comparing all the influence factors,the total arable land area in available and average plot size have bigger effects on arable land intensive use;to a small degree,family′s non-farm income affects labor intensity,yield-increasing input,and labor-saving input;the yield-increasing input decreases significantly when the householder has higher education attainment;the commercialization rates of agricultural products and the planting proportion of cash crops both have unstable influence on ALUI; the share of arable land rented in has few impacts on labor intensity,yield-increasing input,and labor-saving input. 3)There are no differences found in the internal impact mechanism of influence factors on the arable land intensive use behaviors of farm households.However,there are conspicuous disparities in the impact degrees and statistical significance based on varying economic levels.4)Using the results as bases,this study proposes that the government should implement land management and agricultural policies according to local condition.And these policies should decrease land fragmentation to promote scale management of land and arable land use intensification.展开更多
Based on archaeological excavations, 217 samples were collected from the Luotuodun Site. Of them 63 samples from the section plane of the site layer were used for identification analysis of foraminifera, plant debris ...Based on archaeological excavations, 217 samples were collected from the Luotuodun Site. Of them 63 samples from the section plane of the site layer were used for identification analysis of foraminifera, plant debris and seed fossils, and four samples were used for 14C dating and relevant analysis. Through many kinds of experiments, we have drawn some conclusions. Firstly, benthic foraminifera, such as Ammonia compressiuscula and Ammonia cff. sobrina, are found in the lOth layer, indicating that between 7500 and 5400 BC, i.e. before the emergence of the Majiabang Culture, Luotuodun Site and its nearby regions had ever experienced a marine transgression event. Secondly, we have found 450 plant fossils in this site, such as Polygonum sp., Scripus sp., Najas sp., Physalis sp., which indicated lacustrine or swamp environment.展开更多
文摘Soil erosion on sloping field has led to a lot of environmental prob lems. In order to reveal the seriousness of the damage of soil erosion on slopin g fields 137Cs tracer method was used to estimate soil erosion rate. 137Cs refer ence inventory of 2200Bq/m2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivated soil was established in order t o avoid overestimating soil erosion rates. Then based on the soil erosion rates and measured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further discussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts we re that soil layer became thin, soil structure was deteriorated and soil nutrien ts decreased. The off-site impacts were that water bodies were polluted. The in direct impacts of soil erosion on environment were the increase of fertilizer ap plication and energy consumption, and change of adaptability of land uses. Altho ugh erosion intensity was not serious in the study area, its environmental impac ts should not be ignored because of great soil nutrient loss and coarseness of s oil particles.
基金Under the auspices of National Natural Science Foundation of China(No.40971104,40801063,41101160)National Social Science Foundation of China(No.10ZD&M030)Non-profit Industry Financial Program of Ministry of Land and Resources of China(No.200811033)
文摘Using data from the farm household survey conducted in 2009,arable land use intensity(ALUI)and its influence factors at farm household level were investigated by the Tobit model.Suyu District of Suqian City and Taixing City of Jiansu Province,China were chosen as the regions for comparison.The results show that:1)On the average, the ALUI,labor intensity,yield-increasing input,and labor-saving input are 15 238.14 yuan(RMB)/ha,192 d/ha, 7233.01 yuan/ha,and 2451.32 yuan/ha in the less economically developed Suyu District,and 13 020.65 yuan/ha,181 d/ha,5871.82 yuan/ha,and 2625.97 yuan/ha in more economically developed Taixing City.The figures indicate that Suyu District has higher ALUI and labor intensity input but lower labor-saving input.2)Comparing all the influence factors,the total arable land area in available and average plot size have bigger effects on arable land intensive use;to a small degree,family′s non-farm income affects labor intensity,yield-increasing input,and labor-saving input;the yield-increasing input decreases significantly when the householder has higher education attainment;the commercialization rates of agricultural products and the planting proportion of cash crops both have unstable influence on ALUI; the share of arable land rented in has few impacts on labor intensity,yield-increasing input,and labor-saving input. 3)There are no differences found in the internal impact mechanism of influence factors on the arable land intensive use behaviors of farm households.However,there are conspicuous disparities in the impact degrees and statistical significance based on varying economic levels.4)Using the results as bases,this study proposes that the government should implement land management and agricultural policies according to local condition.And these policies should decrease land fragmentation to promote scale management of land and arable land use intensification.
基金National Science and Technology Project, No.2006BAK21B02The Open Foundation of the State Key Laboratory of Loess and Quaternary Geology from the Institute of Earth Environment, CAS, No.SKLLQG0817+2 种基金The Training Foundation of National Basis of Talents, No.J0630535Foundation of Doc-toral Program, No.20050284011Test Foundation of Modern Analyses Center of Nanjing University, No.0209001309
文摘Based on archaeological excavations, 217 samples were collected from the Luotuodun Site. Of them 63 samples from the section plane of the site layer were used for identification analysis of foraminifera, plant debris and seed fossils, and four samples were used for 14C dating and relevant analysis. Through many kinds of experiments, we have drawn some conclusions. Firstly, benthic foraminifera, such as Ammonia compressiuscula and Ammonia cff. sobrina, are found in the lOth layer, indicating that between 7500 and 5400 BC, i.e. before the emergence of the Majiabang Culture, Luotuodun Site and its nearby regions had ever experienced a marine transgression event. Secondly, we have found 450 plant fossils in this site, such as Polygonum sp., Scripus sp., Najas sp., Physalis sp., which indicated lacustrine or swamp environment.
