According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out ...According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out from the perspective of task,technique,necessities and effect on China's grain security of the second national land survey.Through analysis,it can be deemed that data of the second national land survey are reliable.It overcomes defects of traditional survey projects and will be of profound significance for grasping current situations of farmland resources in China.Farmers are grain production entities,while the grain yield survey of farmers is calculated through sampling survey of per unit area yield and the sown area.Therefore,the increase in farmland area may indicate underestimation of the grain yield,and the grain security risk of China will decline accordingly.展开更多
To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second ...To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization.展开更多
文摘According to the data of the second national land survey,the farmland area of China at the end of 2009 was 200 million mu more than the original statistical data.This raises widespread concern.Analysis is carried out from the perspective of task,technique,necessities and effect on China's grain security of the second national land survey.Through analysis,it can be deemed that data of the second national land survey are reliable.It overcomes defects of traditional survey projects and will be of profound significance for grasping current situations of farmland resources in China.Farmers are grain production entities,while the grain yield survey of farmers is calculated through sampling survey of per unit area yield and the sown area.Therefore,the increase in farmland area may indicate underestimation of the grain yield,and the grain security risk of China will decline accordingly.
基金supported by China Geological Survey(DD20230554,DD20230089)the Strategic Priority Research Program of the Chinese Academy of Science(XDA28020302)the funding project of Northeast Geological S&T Innovation Center of China Geological Survey(QCJJ2022-40).
文摘To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization.