There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to furthe...There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to further acidification under current agricultural use. However, there appear to be differences in the rate of acidification, as measured by soil pH change, between soils under perennial pastures in the higher rainfall areas of southern Victoria and soils under annual pastures in the sheep-wheat areas of the north-east. Measurements made on representative soils from both regions showed that the southern soils generally had a higher pH buffer capacity, which was primarily determined by the organic carbon content. There was a consistent relationship between the short-term buffer capacity (measured by titration) and the long-term buffer capacity (measured by incubation), irrespective of the origin of the soils. Exchangeable Al, measured in 0.01 mol·L -1 CaCl 2 , was strongly negatively correlated with pH and the relationship for all soils suggested that Al was adsorbed as a cation with an average charge of 1.2展开更多
In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturb...In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturbance, a grazing trail was carried out during a 21-year period from 1974 at a sown grassland of the National Grassland Research Institute, located in Nishinasuno, the central area of Japan. The data sets of biomass for each mouth(from April to November)of the 21 year period were analyzed in this paper. The botanical composition of aboveground biomass varied greatly with both season and year. The biomass ratio of improved herbage species to invaded native plants gradually decreased each year. This may have been owing to meteorological factors, such as low air-temperature in winter, dry and hot summers, grassland management(including grazing intensity and fertilizer application), and inter-specific competition between native and introduced herbage plants.展开更多
文摘There are about 5 million ha of strongly acid soils (pH < 4.8 in 0.01 mol·L -1 CaCl 2 ) in Victoria and about 11 million ha of mildly acid soils (pH 4.8～5.5) that are considered susceptible to further acidification under current agricultural use. However, there appear to be differences in the rate of acidification, as measured by soil pH change, between soils under perennial pastures in the higher rainfall areas of southern Victoria and soils under annual pastures in the sheep-wheat areas of the north-east. Measurements made on representative soils from both regions showed that the southern soils generally had a higher pH buffer capacity, which was primarily determined by the organic carbon content. There was a consistent relationship between the short-term buffer capacity (measured by titration) and the long-term buffer capacity (measured by incubation), irrespective of the origin of the soils. Exchangeable Al, measured in 0.01 mol·L -1 CaCl 2 , was strongly negatively correlated with pH and the relationship for all soils suggested that Al was adsorbed as a cation with an average charge of 1.2
文摘In order to understand the temporal changes of botanical composition in grassland ecosystem, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturbance, a grazing trail was carried out during a 21-year period from 1974 at a sown grassland of the National Grassland Research Institute, located in Nishinasuno, the central area of Japan. The data sets of biomass for each mouth(from April to November)of the 21 year period were analyzed in this paper. The botanical composition of aboveground biomass varied greatly with both season and year. The biomass ratio of improved herbage species to invaded native plants gradually decreased each year. This may have been owing to meteorological factors, such as low air-temperature in winter, dry and hot summers, grassland management(including grazing intensity and fertilizer application), and inter-specific competition between native and introduced herbage plants.
