It is not understood well that how the effects of land use and fish farming on the contents of alkali metals (Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and Na<sup>+</...It is not understood well that how the effects of land use and fish farming on the contents of alkali metals (Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and Na<sup>+</sup>) in small water bodies of pond and reservoir ecosystems at the watershed scale. In this study, the concentrations of Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and Na<sup>+</sup> in water bodies were measured for 103 ponds and reservoirs used as fish farming or surrounded by different agricultural land use types in the subtropical hilly watershed of Jinjing (105 km<sup>2</sup>), China. The two important environmental factors of fishing farming and agricultural land use influenced the spatial variation the contents of alkali metals. The ponds and reservoirs in residential area had significantly higher concentrations of Ca<sup>2+</sup> and Na<sup>+</sup> than those with other land use types, reflecting the influence of domestic wastewater. Compared with those of natural ponds with non-fish farming, no significant increase of alkali metal contents occurred in fish farming ponds, due to the regular cleaning of ponds by farmers. However, the effect of fish culture on alkali metal contents was still supported indirectly by the fact that the alkali metal contents significantly correlated with nitrate contents in fish farming ponds and but high related with that of DIP in natural ponds. The suitability assessment for irrigation on the pond water indicated that almost all of ponds were suitable for irrigation except some ponds surrounded by residential area and tea plantation. Generally, our results demonstrated that fish farming and agricultural land use affected the contents of alkali metals in ponds and reservoirs. The agricultural water irrigation would be with caution from the ponds with tea plantation and residential area in the subtropical hilly watershed.展开更多
By means of combining auto-extraction with manual interpretation, the current distribution information about cultivated land is obtained. The distribution information of 1992 is extracted from the dynamic polygons of ...By means of combining auto-extraction with manual interpretation, the current distribution information about cultivated land is obtained. The distribution information of 1992 is extracted from the dynamic polygons of 2002. The monitoring mini-system of the cultivated slope land is established. In the system, detailed surveys, focused on the resources of cultivated slope land, are carried out. The results indicate that the area of the cultivated slope land is very large. Meanwhile, there are lots of cultivated steep slopes with gradient above 35°. The areas of steep land cultivated had been slowly reduced from 1992 to 2002. At the same time, the pressures of returning farm land to forestry are great in all counties. The conflicts between population growth, insufficient grain supply and stagnant economic development sharpen increasingly. It is inevitable to improve the agricultural structure.展开更多
Fenlong farming technology was introduced. It has characteristics of very deep tillage and evenly smashing soil,and can evenly smash soil without disturbing soil layers to complete the task of soil preparation. It can...Fenlong farming technology was introduced. It has characteristics of very deep tillage and evenly smashing soil,and can evenly smash soil without disturbing soil layers to complete the task of soil preparation. It can be widely used in cultivated land,saline-alkali land,lime concretion black soil,degraded grassland,etc. After the application of the technology in 34 crops in 24 provinces,it can increase yield by 10%-50% and improve quality by above 5%. Fenlong technology can increase soil reservoir capacity,enhance the infiltration rate of rainwater in soil and make " surplus" effect obvious. If the country plans and promotes the technology in 160 million hm^2 of land( including 67 million hm^2 of cultivated land,20 million hm^2 of saline-alkali land,6. 7 million hm^2 of marginal land and 67 million hm^2 of degraded grassland),the total volume of loosened soil in arable land will increase from 198. 1 billion to 840. 0 billion m^3,and the capacity of a " underground reservoir" will increase by 675 million m^3,while natural precipitation reserves will increase by 162 billion m^3. It can effectively solve food security problems and water resource problems such as drought,floods,and industrial,agricultural and domestic water shortages,as well as serious disaster hazards caused by groundwater that has been evacuated in China.展开更多
文摘It is not understood well that how the effects of land use and fish farming on the contents of alkali metals (Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and Na<sup>+</sup>) in small water bodies of pond and reservoir ecosystems at the watershed scale. In this study, the concentrations of Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup> and Na<sup>+</sup> in water bodies were measured for 103 ponds and reservoirs used as fish farming or surrounded by different agricultural land use types in the subtropical hilly watershed of Jinjing (105 km<sup>2</sup>), China. The two important environmental factors of fishing farming and agricultural land use influenced the spatial variation the contents of alkali metals. The ponds and reservoirs in residential area had significantly higher concentrations of Ca<sup>2+</sup> and Na<sup>+</sup> than those with other land use types, reflecting the influence of domestic wastewater. Compared with those of natural ponds with non-fish farming, no significant increase of alkali metal contents occurred in fish farming ponds, due to the regular cleaning of ponds by farmers. However, the effect of fish culture on alkali metal contents was still supported indirectly by the fact that the alkali metal contents significantly correlated with nitrate contents in fish farming ponds and but high related with that of DIP in natural ponds. The suitability assessment for irrigation on the pond water indicated that almost all of ponds were suitable for irrigation except some ponds surrounded by residential area and tea plantation. Generally, our results demonstrated that fish farming and agricultural land use affected the contents of alkali metals in ponds and reservoirs. The agricultural water irrigation would be with caution from the ponds with tea plantation and residential area in the subtropical hilly watershed.
文摘By means of combining auto-extraction with manual interpretation, the current distribution information about cultivated land is obtained. The distribution information of 1992 is extracted from the dynamic polygons of 2002. The monitoring mini-system of the cultivated slope land is established. In the system, detailed surveys, focused on the resources of cultivated slope land, are carried out. The results indicate that the area of the cultivated slope land is very large. Meanwhile, there are lots of cultivated steep slopes with gradient above 35°. The areas of steep land cultivated had been slowly reduced from 1992 to 2002. At the same time, the pressures of returning farm land to forestry are great in all counties. The conflicts between population growth, insufficient grain supply and stagnant economic development sharpen increasingly. It is inevitable to improve the agricultural structure.
基金Supported by the Special Project for Innovation-driven Development of Guangxi(Guike AA17204037)
文摘Fenlong farming technology was introduced. It has characteristics of very deep tillage and evenly smashing soil,and can evenly smash soil without disturbing soil layers to complete the task of soil preparation. It can be widely used in cultivated land,saline-alkali land,lime concretion black soil,degraded grassland,etc. After the application of the technology in 34 crops in 24 provinces,it can increase yield by 10%-50% and improve quality by above 5%. Fenlong technology can increase soil reservoir capacity,enhance the infiltration rate of rainwater in soil and make " surplus" effect obvious. If the country plans and promotes the technology in 160 million hm^2 of land( including 67 million hm^2 of cultivated land,20 million hm^2 of saline-alkali land,6. 7 million hm^2 of marginal land and 67 million hm^2 of degraded grassland),the total volume of loosened soil in arable land will increase from 198. 1 billion to 840. 0 billion m^3,and the capacity of a " underground reservoir" will increase by 675 million m^3,while natural precipitation reserves will increase by 162 billion m^3. It can effectively solve food security problems and water resource problems such as drought,floods,and industrial,agricultural and domestic water shortages,as well as serious disaster hazards caused by groundwater that has been evacuated in China.
