In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4+ and the resin adsorption of N was studied in a ...In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4+ and the resin adsorption of N was studied in a paddy soil, typical for Zhejiang Province, China. Oxalic and citric acids under low pH conditions, in combination with proton secretion, favored the mobilization of NH4+ ions and increased resin adsorption of N. The release of non-exchangeable NH4+ was associated with less formation of iron oxides. These could coat clay minerals and thus hinder the diffusion of NH4+ ions out of the interlayer. Protons enhanced the release of NH4+, and then they could enter the wedge zones of the clay minerals and displace non-exchangeable NH4+ ions.展开更多
Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement...Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.展开更多
In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan Co...In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan County, and the effects of the regulation of different ratios of basal to topdressed nitrogen on the yield of wheat and the contents of different forms of potassium in the soil were studied. The re- sults indicated that in the condition of straw-return, the yield of wheat was the high- est after the treatments of the ratios of basal to topdressed nitrogen of 7：3 and 6：4. As to the contents of different forms of potassium, the contents of water-soluble potassium, exchangeable potassium and total potassium treated by the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the highest, and the differences of non-exchangeable potassium among all treatments were not significant. Under the experiment condition, the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the best treatments, they can increase the wheat yield and the contents of available potassium and total potassium in the soil.展开更多
Sustainable potassium （K） management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses o...Sustainable potassium （K） management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses of grain yield of wheat （Triticum aestivurn L.） and maize （Zea mays L.）, K efficiency, and partial balance （difference between K input through fertilizer and K output in the aboveground biomass） during 15- （1990-2005） or 18-year （1990-2008） K fertilizations at five distinctive agroecologicai zones across China. Compared to the inorganic nitrogen （N） and phosphorus （P） fertilization, the inorganic NPK fertilization significantly increased grain yields of wheat （21%） and maize （16% 72%） at Qiyang and Changping, where soils have low exchangeable and non-exchangeable K contents, but not at Uriimqi, Yangling and Zhengzhou, where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants. Compared to the inorganic NPK fertilization, the inorganic NPK （30% N） and organic manure （70~~ N） fertilization （NPKM） increased grain yields of wheat （14%-40%） and maize （9%-6170） at four sites, but not at Zhengzhou. For a productivity of wheat at 2-5 t ha-1 or maize at 3-6 t ha 1, 13-26 or 9-17 kg K ha 1 were required to produce 1.0 t wheat or maize. The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha-1 year-1 less than the NPK fertilization, which accumulated 28 kg ha 1 year-1 less K than the NPKM fertilization. A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM t＇ertilization is urgently needed to increase both crop yield and K use efficiency at different agroecologicai zones across China.展开更多
Multivariate statistical technique was used to determine the potassium （K＋） status and to assess soil fertility and K leaching potential in some calcareous soils. Water-soluble K＋ （H20-K） and ammonium acetate-ex...Multivariate statistical technique was used to determine the potassium （K＋） status and to assess soil fertility and K leaching potential in some calcareous soils. Water-soluble K＋ （H20-K） and ammonium acetate-extractable K＋ （NHaOAc- K） ranged from 0.019 to 0.590 （mean value 0.095） and 0.390 to 3.320 （mean value 0.954） cmolc kg-1, respectively. The nitric acid-extractable K＋ （HNO3-K） varied from 1.03 to 13.63 （mean value 5.37） cmolc kg-1. The proportion of H20-K ranged from 0.34% to 14.8% of HNO3-K, and 2.2% to 53.2% of NHaOAc-K. The proportion of NHaOAc-K ranged from 5.8% to 80% of HNO3-K （mean value 23% of HNOa-K）. The tendency of the soil to lose K＋ by leaching was examined by determining K＋-Ca2＋ exchange isotherms. The soils mostly had moderate to high values of K＋ sorption capacity, ranging from 10% to 58% （mean value 28%） of added K＋. The Gapon coefficient varied widely from 1.1 to 12.0 （L mol-1）-1/2. Clay minerals were dominated by illite, smectites and vermiculite with small amounts of kaolinite. Principal component analysis （PCA） showed that the first four components accounted for 27.7%, 21.4%, 13.8%, and 8.9% of total variation, respectively. The non-hierarchical cluster analysis （k-means clustering） grouped 75 sampling sites into six clusters, based on the similarity of soil quality characteristics. The results suggested that such classes could form a basis for variable-rate application to maintain an adequate K＋ status for crop production and to reduce potential K＋ loss from soil by leaching.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30070428), the Research Foundation ofGermany, the Zhejiang Province Natural Science Foundation (No. 399485) and the Foundation for University PhD GrantingDiscipline by the Ministr
文摘In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4+ and the resin adsorption of N was studied in a paddy soil, typical for Zhejiang Province, China. Oxalic and citric acids under low pH conditions, in combination with proton secretion, favored the mobilization of NH4+ ions and increased resin adsorption of N. The release of non-exchangeable NH4+ was associated with less formation of iron oxides. These could coat clay minerals and thus hinder the diffusion of NH4+ ions out of the interlayer. Protons enhanced the release of NH4+, and then they could enter the wedge zones of the clay minerals and displace non-exchangeable NH4+ ions.
文摘Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.
基金Supported by the Project of National Science and Technology Support Plan-"Integration and Demonstration ration of Straw Resources Recycling Technologies in Huang-HuaiHai Plain Area"(2012BAD14B07)the Project of Major Application Technology Innovation of Agriculture in Shandong Province-"Study on Recycling Technology of Waste Resourcization in Large-scale Farm"+1 种基金the Foundation for Outstanding Young Scientist in Shandong Province-"Study on the Mechanism of the Effect of Drip Irrigation with Saline Water on Soil Environment and Its Crop Response"(BS2011NY017)the Project of National Natural Science Foundation-"Study on the Allocation Pattern and Interface Control of Salinity under the Condition of Brackish Water Irrigation"(51209130)~~
文摘In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan County, and the effects of the regulation of different ratios of basal to topdressed nitrogen on the yield of wheat and the contents of different forms of potassium in the soil were studied. The re- sults indicated that in the condition of straw-return, the yield of wheat was the high- est after the treatments of the ratios of basal to topdressed nitrogen of 7：3 and 6：4. As to the contents of different forms of potassium, the contents of water-soluble potassium, exchangeable potassium and total potassium treated by the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the highest, and the differences of non-exchangeable potassium among all treatments were not significant. Under the experiment condition, the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the best treatments, they can increase the wheat yield and the contents of available potassium and total potassium in the soil.
基金Supported by the National Basic Research Program (973 program) of China (Nos. 2011CB100501 and 2007CB309108)the National Natural Science Foundation of China (No. 41071200)
文摘Sustainable potassium （K） management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses of grain yield of wheat （Triticum aestivurn L.） and maize （Zea mays L.）, K efficiency, and partial balance （difference between K input through fertilizer and K output in the aboveground biomass） during 15- （1990-2005） or 18-year （1990-2008） K fertilizations at five distinctive agroecologicai zones across China. Compared to the inorganic nitrogen （N） and phosphorus （P） fertilization, the inorganic NPK fertilization significantly increased grain yields of wheat （21%） and maize （16% 72%） at Qiyang and Changping, where soils have low exchangeable and non-exchangeable K contents, but not at Uriimqi, Yangling and Zhengzhou, where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants. Compared to the inorganic NPK fertilization, the inorganic NPK （30% N） and organic manure （70~~ N） fertilization （NPKM） increased grain yields of wheat （14%-40%） and maize （9%-6170） at four sites, but not at Zhengzhou. For a productivity of wheat at 2-5 t ha-1 or maize at 3-6 t ha 1, 13-26 or 9-17 kg K ha 1 were required to produce 1.0 t wheat or maize. The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha-1 year-1 less than the NPK fertilization, which accumulated 28 kg ha 1 year-1 less K than the NPKM fertilization. A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM t＇ertilization is urgently needed to increase both crop yield and K use efficiency at different agroecologicai zones across China.
文摘Multivariate statistical technique was used to determine the potassium （K＋） status and to assess soil fertility and K leaching potential in some calcareous soils. Water-soluble K＋ （H20-K） and ammonium acetate-extractable K＋ （NHaOAc- K） ranged from 0.019 to 0.590 （mean value 0.095） and 0.390 to 3.320 （mean value 0.954） cmolc kg-1, respectively. The nitric acid-extractable K＋ （HNO3-K） varied from 1.03 to 13.63 （mean value 5.37） cmolc kg-1. The proportion of H20-K ranged from 0.34% to 14.8% of HNO3-K, and 2.2% to 53.2% of NHaOAc-K. The proportion of NHaOAc-K ranged from 5.8% to 80% of HNO3-K （mean value 23% of HNOa-K）. The tendency of the soil to lose K＋ by leaching was examined by determining K＋-Ca2＋ exchange isotherms. The soils mostly had moderate to high values of K＋ sorption capacity, ranging from 10% to 58% （mean value 28%） of added K＋. The Gapon coefficient varied widely from 1.1 to 12.0 （L mol-1）-1/2. Clay minerals were dominated by illite, smectites and vermiculite with small amounts of kaolinite. Principal component analysis （PCA） showed that the first four components accounted for 27.7%, 21.4%, 13.8%, and 8.9% of total variation, respectively. The non-hierarchical cluster analysis （k-means clustering） grouped 75 sampling sites into six clusters, based on the similarity of soil quality characteristics. The results suggested that such classes could form a basis for variable-rate application to maintain an adequate K＋ status for crop production and to reduce potential K＋ loss from soil by leaching.
