The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double...The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double-cropping systems are leading to large-scale non-point source pollution of aquifers. In an interdisciplinary approach, four-year (1995-1998) field trials were carried out in two representative areas (Jurong County and Wuxi City) of the Taihu Region. Five farmers' field sites were chosen in each of the 2 locations, with each site divided into 'standard' (farmers' practice) and 'reduced' (by 30%-40%) N fertilization. For both fertilization intensities, N balance surpluses and monetary returns from grain sales minus fertilizer expenditures were calculated in an economic assessment. Based on the field trials, the mineral N fertilizer application rates reduced by about 10% for rice and 20%-30% for wheat were recommended in 1999. Since 1999, the research focused on the trends in N fertilizer application rates and changes in grain and agricultural commodities prices.Summer rice N fertilizer use, in Wuxi City as of 2001, dropped by roughly 25%, while for winter wheat it decreased by 10%-20%, compared to the 1995-1998 period. This has been achieved not only by grain policy and price changes, but also by an increased environmental awareness from government officials. Nitrogen balance surpluses in Anzhen Town (of Wuxi City) have consequently diminished by 50%-75% in rice and by up to 40% in wheat, with reductions being achieved without concomitant decreases in physical grain yields or returns from sales minus fertilizer costs.展开更多
Rice production plays a crucial role in the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity...Rice production plays a crucial role in the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity. In this study, field sampling in a typical red soil region of subtropical China, Jiangxi Province, was used to observe changes in the soil physical, chemical, and biological properties in a cultivation chronosequence of paddy fields. After cultivation, clay (< 0.002 mm) content in the soil…展开更多
Xiangxiang 2A has an evident drawback, i.e., instability in male sterility under higher temperature conditions resulting from the existence of minor restoring genes in it, which greatly hampered the extension of its e...Xiangxiang 2A has an evident drawback, i.e., instability in male sterility under higher temperature conditions resulting from the existence of minor restoring genes in it, which greatly hampered the extension of its elite hybrid Xiangyou 63 with both high yield and fine quality in commercial production. To improve Xiangxiang 2A, the hybridization of Xiangxiang 2B with V20 B was made again in 1990. A new aromatic CMS line Xinxiang A was successfully developed in 1994. It not only retains the favorable characteristics of Xiangxiang 2A in grain quality and combining ability, but also expresses complete and stable male sterility and high seed production yield potential. Up to now, by using it as female parent, a series of quasi aromatic hybrids have been developed. Some of them have been released to farmers. Because such hybrids can not only yield higher or as high as but also possess a better grain quality than the current common high yielding hybrid rice varieties,so that they are preferred and well welcome by the farmers in China. The planting area under these hybrids is increasing rapidly in China.展开更多
基金Project supported by the Volkswagen-Foundation, Germany (No. Ⅱ/69 948) the Institute of Soil Science, Chinese Academy of Sciences.
文摘The Taihu Region in eastern China is one of China's most intensive agricultural regions and also one of the economically most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double-cropping systems are leading to large-scale non-point source pollution of aquifers. In an interdisciplinary approach, four-year (1995-1998) field trials were carried out in two representative areas (Jurong County and Wuxi City) of the Taihu Region. Five farmers' field sites were chosen in each of the 2 locations, with each site divided into 'standard' (farmers' practice) and 'reduced' (by 30%-40%) N fertilization. For both fertilization intensities, N balance surpluses and monetary returns from grain sales minus fertilizer expenditures were calculated in an economic assessment. Based on the field trials, the mineral N fertilizer application rates reduced by about 10% for rice and 20%-30% for wheat were recommended in 1999. Since 1999, the research focused on the trends in N fertilizer application rates and changes in grain and agricultural commodities prices.Summer rice N fertilizer use, in Wuxi City as of 2001, dropped by roughly 25%, while for winter wheat it decreased by 10%-20%, compared to the 1995-1998 period. This has been achieved not only by grain policy and price changes, but also by an increased environmental awareness from government officials. Nitrogen balance surpluses in Anzhen Town (of Wuxi City) have consequently diminished by 50%-75% in rice and by up to 40% in wheat, with reductions being achieved without concomitant decreases in physical grain yields or returns from sales minus fertilizer costs.
文摘Rice production plays a crucial role in the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity. In this study, field sampling in a typical red soil region of subtropical China, Jiangxi Province, was used to observe changes in the soil physical, chemical, and biological properties in a cultivation chronosequence of paddy fields. After cultivation, clay (< 0.002 mm) content in the soil…
文摘Xiangxiang 2A has an evident drawback, i.e., instability in male sterility under higher temperature conditions resulting from the existence of minor restoring genes in it, which greatly hampered the extension of its elite hybrid Xiangyou 63 with both high yield and fine quality in commercial production. To improve Xiangxiang 2A, the hybridization of Xiangxiang 2B with V20 B was made again in 1990. A new aromatic CMS line Xinxiang A was successfully developed in 1994. It not only retains the favorable characteristics of Xiangxiang 2A in grain quality and combining ability, but also expresses complete and stable male sterility and high seed production yield potential. Up to now, by using it as female parent, a series of quasi aromatic hybrids have been developed. Some of them have been released to farmers. Because such hybrids can not only yield higher or as high as but also possess a better grain quality than the current common high yielding hybrid rice varieties,so that they are preferred and well welcome by the farmers in China. The planting area under these hybrids is increasing rapidly in China.
