Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (E-oc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the...Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (E-oc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to Z mg/L. In comparing with existing methods of K-oc, SCLC possesses rapid, online and accurate characteristics.展开更多
Studying the relationship between climate factors and soil organic carbon （SOC） is vitally important. However, how SOC responses to climate （temperature and precipitation） at cohesive extents is poorly studied. Tw...Studying the relationship between climate factors and soil organic carbon （SOC） is vitally important. However, how SOC responses to climate （temperature and precipitation） at cohesive extents is poorly studied. Two transects of approximately the same length （transect P and transect T） were selected to examine the variation of SOC content in relation to mean annual temperature （MAT） and mean annual precipitation （MAP）. The coefficients of partial correlation between SOC density and MAT （Rt） and MAP （Rp） were determined to quantify the relationships between SOC density and the two climate factors. The results indicated that for transect T, Rt was statistically significant once the extent level was greater than or equal to two fundamental extent units, while for transect P, Rp showed statistical significance only at extent levels which were greater than two fundamental extent traits. At the same extent levels but in different transects, Rts exhibited no zonal difference, but Rps did once the extent level was greater than two fundamental extent units. Therefore, to study the relationship between SOC density and different climate factors, different minimum extent levels should be ex- amined. The results of this paper could deepen the understanding of the impacts that SOC pool has on terrestrial ecosystem and global carbon cycling.展开更多
Soil aggregates are an important controlling factor for the physico-chemical and biological processes such as ammonium(NH;) retention. Straw return to the field is increasingly recommended to promote soil carbon(C) se...Soil aggregates are an important controlling factor for the physico-chemical and biological processes such as ammonium(NH;) retention. Straw return to the field is increasingly recommended to promote soil carbon(C) sequestration and improve crop yields. However, the effects of straw return on NH;retention at soil aggregate level in agricultural soils have seldom been investigated. This study aimed to evaluate the influences of long-term straw return on NH;adsorption and fixation in microaggregates(<0.25 mm) with or without soil organic carbon(SOC) oxidization. Soil samples were collected from plots of three treatments, i.e., no fertilizer(CK), inorganic NPK fertilizers(NPK), and inorganic NPK fertilizers with rice straw return(NPKS), from a 20-year-old field trial with rice-wheat rotations in Taihu Lake Region, China. Soil aggregates were separated using wet-sieving method. The SOC of microaggregates was oxidized by H;O;. The results showed that longterm straw return significantly increased SOC and NH;adsorption, but inhibited NH;fixation in microaggregates. NH;adsorption potential and strength-obtained from adsorption isotherms-increased, but NH;fixation decreased along with increasing SOC in microaggregates, indicating the important role of SOC in NH;adsorption and fixation. This was verified by the SOC oxidization test that showed a relative decrease in NH;adsorption potential for the NPKS treatment and an increase in NH;fixation in all three treatments. Therefore, long-term straw return influences NH;adsorption and fixation by enhancing SOC content and could improve N availability for crop uptake and minimize applied N fertilizer losses in rice-wheat cropping systems.展开更多
基金Bayer AG and Chinese Academy of Agricultural Sciences for kindly supplying the pesticides.
文摘Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (E-oc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to Z mg/L. In comparing with existing methods of K-oc, SCLC possesses rapid, online and accurate characteristics.
基金Under the auspices of Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues of Chinese Academy of Sciences(No.XDA05050503)National Key Technology Research and Development Program of China(No.2013BAD11B00)National Natural Science Foundation of China(No.41301242)
文摘Studying the relationship between climate factors and soil organic carbon （SOC） is vitally important. However, how SOC responses to climate （temperature and precipitation） at cohesive extents is poorly studied. Two transects of approximately the same length （transect P and transect T） were selected to examine the variation of SOC content in relation to mean annual temperature （MAT） and mean annual precipitation （MAP）. The coefficients of partial correlation between SOC density and MAT （Rt） and MAP （Rp） were determined to quantify the relationships between SOC density and the two climate factors. The results indicated that for transect T, Rt was statistically significant once the extent level was greater than or equal to two fundamental extent units, while for transect P, Rp showed statistical significance only at extent levels which were greater than two fundamental extent traits. At the same extent levels but in different transects, Rts exhibited no zonal difference, but Rps did once the extent level was greater than two fundamental extent units. Therefore, to study the relationship between SOC density and different climate factors, different minimum extent levels should be ex- amined. The results of this paper could deepen the understanding of the impacts that SOC pool has on terrestrial ecosystem and global carbon cycling.
基金funded by the National Key Research and Development Program of China(2016YFD0200307 and 2016YFD0200108)the National Natural Science Foundation of China(41401295 and 41271309)。
文摘Soil aggregates are an important controlling factor for the physico-chemical and biological processes such as ammonium(NH;) retention. Straw return to the field is increasingly recommended to promote soil carbon(C) sequestration and improve crop yields. However, the effects of straw return on NH;retention at soil aggregate level in agricultural soils have seldom been investigated. This study aimed to evaluate the influences of long-term straw return on NH;adsorption and fixation in microaggregates(<0.25 mm) with or without soil organic carbon(SOC) oxidization. Soil samples were collected from plots of three treatments, i.e., no fertilizer(CK), inorganic NPK fertilizers(NPK), and inorganic NPK fertilizers with rice straw return(NPKS), from a 20-year-old field trial with rice-wheat rotations in Taihu Lake Region, China. Soil aggregates were separated using wet-sieving method. The SOC of microaggregates was oxidized by H;O;. The results showed that longterm straw return significantly increased SOC and NH;adsorption, but inhibited NH;fixation in microaggregates. NH;adsorption potential and strength-obtained from adsorption isotherms-increased, but NH;fixation decreased along with increasing SOC in microaggregates, indicating the important role of SOC in NH;adsorption and fixation. This was verified by the SOC oxidization test that showed a relative decrease in NH;adsorption potential for the NPKS treatment and an increase in NH;fixation in all three treatments. Therefore, long-term straw return influences NH;adsorption and fixation by enhancing SOC content and could improve N availability for crop uptake and minimize applied N fertilizer losses in rice-wheat cropping systems.
