Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carb...Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.展开更多
Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two question...Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.展开更多
Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the cas...Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.展开更多
We sampled the sediments of the East China Sea during 2005 and 2006, and analysed the contents of the biogenic matters: biogenic silica, organic carbon, and organic nitrogen. From the surface distribution we found the...We sampled the sediments of the East China Sea during 2005 and 2006, and analysed the contents of the biogenic matters: biogenic silica, organic carbon, and organic nitrogen. From the surface distribution we found the contents of these substances to be in the ranges of 0.72%-1.64%, 0.043%-0.82%, and 0.006%-0.11%, respectively. Their distributions were similar to each other, being high inside the Hangzhou Bay and low outside the bay. The vertical variations of the contents were also similar. In order to discuss the relation between them we analysed the variations of content with depth. They increased in the first 7 cm and then decreased with depth. The peaks were found at depths between 20 to 25 cm. The distribution of carbonate showed an opposite trend to that of biogenic matters. The content of total carbon was relatively stable with respect to depth, and the ratio of high organic carbon to carbonate showed a low burial efficiency of carbonate, which means that the main burial of carbon is organic carbon. In order to discuss the source of organic matters, the ratio of organic carbon to organic nitrogen was calculated, which was 8.01 to 9.65, indicating that the organic matter in the sediments was derived mainly from phytoplankton in the seawater.展开更多
Cover crop system has shown a potential approach to improving carbon sequestration and environmental quality. Six of each winter and summer cover crops were subsequently grown in two soils, Krome gravelly loam soil (K...Cover crop system has shown a potential approach to improving carbon sequestration and environmental quality. Six of each winter and summer cover crops were subsequently grown in two soils, Krome gravelly loam soil (KGL), and Quincy fine sandy soil (QFS), in phytotrons at 3 temperatures (10/20, 15/25, 25/30oC for winter/summer cover crops) to investigate their contributions for carbon (C) sequestration. Among winter cover crops, the highest and the lowest amounts of C accumulated were by bellbean (Vicia faba L.), 597 g/m2 and white clover (Trifolium repens), 149 g/m2, respectively, in the QFS soil. Among summer cover crops, sunn hemp (Crotalaria juncea L.) accumulated the largest quantity of C (481 g/m2), while that by castorbean (Ricinus communis) was 102 g/m2 at 30oC in the KGL soil. The mean net C remained in the residues following the 127 d decomposition were 187 g/m2 of C (73% of the total) and 91 g/m2 (52% of the total) for the winter and summer cover crops, respectively. Following a whole cycle of winter and summer cover crops grown, the mean soil organic C (SOC) increased by 13.8 and 39.1% in the KGL and QFS soil, respectively, compared to the respective soils before. The results suggest that triticale, ryegrass, and bellbean are the promising winter cover crops in the QFS soil, while sunn hemp, velvetbean (Mucuna pruriens), and sorghum sudangrass (Sorghum bicolor ×S. bicolor) are recommended summer cover crops for both soils under favorable temperatures.展开更多
文摘Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.
基金supported in part by the National Basic Research Program of China (2009CB421303)supported by National Natural Science Foundation of China (30970546)
文摘Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.
文摘Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.
基金supported by the National Key Basic Research Program (973) (Grant No. 2010CB428701)
文摘We sampled the sediments of the East China Sea during 2005 and 2006, and analysed the contents of the biogenic matters: biogenic silica, organic carbon, and organic nitrogen. From the surface distribution we found the contents of these substances to be in the ranges of 0.72%-1.64%, 0.043%-0.82%, and 0.006%-0.11%, respectively. Their distributions were similar to each other, being high inside the Hangzhou Bay and low outside the bay. The vertical variations of the contents were also similar. In order to discuss the relation between them we analysed the variations of content with depth. They increased in the first 7 cm and then decreased with depth. The peaks were found at depths between 20 to 25 cm. The distribution of carbonate showed an opposite trend to that of biogenic matters. The content of total carbon was relatively stable with respect to depth, and the ratio of high organic carbon to carbonate showed a low burial efficiency of carbonate, which means that the main burial of carbon is organic carbon. In order to discuss the source of organic matters, the ratio of organic carbon to organic nitrogen was calculated, which was 8.01 to 9.65, indicating that the organic matter in the sediments was derived mainly from phytoplankton in the seawater.
文摘Cover crop system has shown a potential approach to improving carbon sequestration and environmental quality. Six of each winter and summer cover crops were subsequently grown in two soils, Krome gravelly loam soil (KGL), and Quincy fine sandy soil (QFS), in phytotrons at 3 temperatures (10/20, 15/25, 25/30oC for winter/summer cover crops) to investigate their contributions for carbon (C) sequestration. Among winter cover crops, the highest and the lowest amounts of C accumulated were by bellbean (Vicia faba L.), 597 g/m2 and white clover (Trifolium repens), 149 g/m2, respectively, in the QFS soil. Among summer cover crops, sunn hemp (Crotalaria juncea L.) accumulated the largest quantity of C (481 g/m2), while that by castorbean (Ricinus communis) was 102 g/m2 at 30oC in the KGL soil. The mean net C remained in the residues following the 127 d decomposition were 187 g/m2 of C (73% of the total) and 91 g/m2 (52% of the total) for the winter and summer cover crops, respectively. Following a whole cycle of winter and summer cover crops grown, the mean soil organic C (SOC) increased by 13.8 and 39.1% in the KGL and QFS soil, respectively, compared to the respective soils before. The results suggest that triticale, ryegrass, and bellbean are the promising winter cover crops in the QFS soil, while sunn hemp, velvetbean (Mucuna pruriens), and sorghum sudangrass (Sorghum bicolor ×S. bicolor) are recommended summer cover crops for both soils under favorable temperatures.
