The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical mod...The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical models based on partial least squares （PLS） regression were defined from the measured reflectance spectra （0.4 to 2.4 μm）. Here, reliable estimates were obtained for nitrogen content, but prediction accuracy was only moderate for organic carbon. For nitrogen, the real spatial pattern of within-field variability was reproduced with high accuracy. The results indicate the potential of this method as a quick screening tool for the spatial assessment of nitrogen and organic carbon, and therefore an appropriate alternative to time- and cost-intensive chemical analysis in the laboratory.展开更多
The large shift of surplus labor from agriculture to industry and services is seen in many countries around the world as well as in Vietnam in the process of industrialization and modernization of the country that has...The large shift of surplus labor from agriculture to industry and services is seen in many countries around the world as well as in Vietnam in the process of industrialization and modernization of the country that has set questions about the sustainability of rural surplus labor： is there still a source of surplus labor in rural areas？ If so, how large is the source of surplus labor and how long it can be lasting？ These questions were hotly debated in the literature abroad. But in Vietnam there is very little or hardly exchanged opinions about the concepts and methods of measurement of surplus labor in general and surplus labor in agriculture in particular. This article refers to the measurement approach of surplus labor in agriculture in Vietnam.展开更多
Salinity is a well known phenomenon throughout the agricultural fields of Algeria, where irrigation uses poor quality waters. This paper describes the results of a survey of farmers＇ perception of salinity with regar...Salinity is a well known phenomenon throughout the agricultural fields of Algeria, where irrigation uses poor quality waters. This paper describes the results of a survey of farmers＇ perception of salinity with regard to salinity assessment. In the lower Cheliff plain, 42 farmers were interviewed using semi-structured questionnaires, and simultaneously, water and soil＇s salinity were measured in the laboratory. The results from this sample analysis were compared to the farmers＇ individual opinion on soil and water salinity. Conclusions point to a positive agreement between the two approaches because farmers are familiar with techniques and strategies to mitigate salinity effects. However, they do not perceive the risk of newly changing irrigation water source, which open up to soil degradation hazard.展开更多
The improved analytic hierachy process method was utilized in this paper,and a variety of factors influencing the food production were classified into several interrelated orderly objectives layers;based on the works ...The improved analytic hierachy process method was utilized in this paper,and a variety of factors influencing the food production were classified into several interrelated orderly objectives layers;based on the works above,this paper made an scientific assessment on the influencing factors of food production and production potential of the various regions in the Songnen Plain.The weights and composite indices were calculated with the method of solving weight by AHP's accumulation factor sequence evaluating data,and were processed by single-level sorting and general sorting.The result showed that,the region of Changchun had the biggest potential for improving food production,but smallest for Heihe region.The key reason for the food production discrepancy of a variety of regions in Songnen Plain is the differences in scale of production and climatic conditions,the weight coefficients of which are 0.3654 and 0.2742;however,the weight coefficients of agricultural science and technology investment is very low just 0.1703,which should be increasted in the future.展开更多
文摘The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical models based on partial least squares （PLS） regression were defined from the measured reflectance spectra （0.4 to 2.4 μm）. Here, reliable estimates were obtained for nitrogen content, but prediction accuracy was only moderate for organic carbon. For nitrogen, the real spatial pattern of within-field variability was reproduced with high accuracy. The results indicate the potential of this method as a quick screening tool for the spatial assessment of nitrogen and organic carbon, and therefore an appropriate alternative to time- and cost-intensive chemical analysis in the laboratory.
文摘The large shift of surplus labor from agriculture to industry and services is seen in many countries around the world as well as in Vietnam in the process of industrialization and modernization of the country that has set questions about the sustainability of rural surplus labor： is there still a source of surplus labor in rural areas？ If so, how large is the source of surplus labor and how long it can be lasting？ These questions were hotly debated in the literature abroad. But in Vietnam there is very little or hardly exchanged opinions about the concepts and methods of measurement of surplus labor in general and surplus labor in agriculture in particular. This article refers to the measurement approach of surplus labor in agriculture in Vietnam.
文摘Salinity is a well known phenomenon throughout the agricultural fields of Algeria, where irrigation uses poor quality waters. This paper describes the results of a survey of farmers＇ perception of salinity with regard to salinity assessment. In the lower Cheliff plain, 42 farmers were interviewed using semi-structured questionnaires, and simultaneously, water and soil＇s salinity were measured in the laboratory. The results from this sample analysis were compared to the farmers＇ individual opinion on soil and water salinity. Conclusions point to a positive agreement between the two approaches because farmers are familiar with techniques and strategies to mitigate salinity effects. However, they do not perceive the risk of newly changing irrigation water source, which open up to soil degradation hazard.
文摘The improved analytic hierachy process method was utilized in this paper,and a variety of factors influencing the food production were classified into several interrelated orderly objectives layers;based on the works above,this paper made an scientific assessment on the influencing factors of food production and production potential of the various regions in the Songnen Plain.The weights and composite indices were calculated with the method of solving weight by AHP's accumulation factor sequence evaluating data,and were processed by single-level sorting and general sorting.The result showed that,the region of Changchun had the biggest potential for improving food production,but smallest for Heihe region.The key reason for the food production discrepancy of a variety of regions in Songnen Plain is the differences in scale of production and climatic conditions,the weight coefficients of which are 0.3654 and 0.2742;however,the weight coefficients of agricultural science and technology investment is very low just 0.1703,which should be increasted in the future.
