Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying pro...Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying processes for straw and manure combined application is relatively poor.In this study,rice straw(carbon(C)/nitrogen(N)ratio of 63),green manure(hairy vetch,C/N ratio of 14),and their mixtures(C/N ratio of 25 and 35)were added into a paddy soil,and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment.All plant residue treatments significantly enhanced C〇2 and CH4 emissions,but decreased N2O emission.Dissolved organic C(DOC)and N(DON)and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment,and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments.Changes in plant residue C/N ratio,DOC/DON ratio,and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil.Additionally,the treatment with green manure alone yielded the largest C and N losses,and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential(nGWP)among the amended treatments.In conclusion,the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw(N immobilization)or the sole application of leguminous green manure(high C and N losses),and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.展开更多
The study was to determine the long-term effects of subtropical monoculture and rotational cropping systems and fertilization on soil enzyme activities and soil C, N, and P levels. Cropping systems included continuous...The study was to determine the long-term effects of subtropical monoculture and rotational cropping systems and fertilization on soil enzyme activities and soil C, N, and P levels. Cropping systems included continuous sorghum(Sorghum bicolor L.), cotton(Gossypium hirsutum L.), corn(Zea mays L.), and cotton/sorghum rotations after 26 years of treatment imposition. Soil under continuous sorghum and continuous corn had 15% and 11%, respectively, greater C concentrations than soil under continuous cotton.Organic C was 10% higher at 0–7.5 cm than at 7.5–15 cm. Total N followed similar trends with soil depth as organic C. Continuous sorghum had 19% higher total N than other crop species and rotations. With fertilization, continuous cotton had the highest total P at 0–7.5 cm and sorghum had the highest at 7.5–15 cm. Soil total P was 14% higher at 0–7.5 than at 7.5–15 cm, and fertilization increased 15% total P compared to unfertilized soil. Arylsulfatase, alkaline phosphatase, and β-d-glucosidase activity were the highest for sorghum and the lowest for cotton. Rotation increased enzyme activities compared to continuous cotton but not for continuous sorghum. Of all crop species and rotations, continuous cotton generally showed the lowest levels of organic matter and enzyme activities after 26 years. Fertilization significantly increased the yields for all cropping systems, but rotation had no significant effect on either sorghum or cotton lint yield compared to each crop grown in monoculture. Long-term cropping did not increase soil organic matter levels beyond short-term gains, indicating the difficulty in promoting C sequestration in subtropical soils.展开更多
基金This work was supported by the China Agriculture Research System-Green Manure,the Virtual Joint Nitrogen Centre(N-Circle)(No.B B/N 013484/1)the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(2013-2017)the Chinese Outstanding Talents Program in Agricultural Science.
文摘Returning rice straw and leguminous green manure alone or in combination to soil is effective in improving soil fertility in South China.Despite the popularity of this practice,our understanding o f the underlying processes for straw and manure combined application is relatively poor.In this study,rice straw(carbon(C)/nitrogen(N)ratio of 63),green manure(hairy vetch,C/N ratio of 14),and their mixtures(C/N ratio of 25 and 35)were added into a paddy soil,and their effects on soil N availability and C or N loss under waterlogged conditions were evaluated in a 100-d incubation experiment.All plant residue treatments significantly enhanced C〇2 and CH4 emissions,but decreased N2O emission.Dissolved organic C(DOC)and N(DON)and microbial biomass C in soil and water-soluble organic C and N and mineral N in the upper aqueous layer above soil were also enhanced by all the plant residue treatments except the rice straw treatment,and soil microbial biomass N and mineral N were lower in the rice straw treatment than in the other treatments.Changes in plant residue C/N ratio,DOC/DON ratio,and cellulose content significantly affected greenhouse gas emissions and active C and N concentrations in soil.Additionally,the treatment with green manure alone yielded the largest C and N losses,and incorporation of the plant residue mixture with a C/N ratio of 35 caused the largest net global warming potential(nGWP)among the amended treatments.In conclusion,the co-incorporation of rice straw and green manure can alleviate the limitation resulting from only applying rice straw(N immobilization)or the sole application of leguminous green manure(high C and N losses),and the residue mixture with a C/N ratio of 25 is a better option because of lower nGWP.
文摘The study was to determine the long-term effects of subtropical monoculture and rotational cropping systems and fertilization on soil enzyme activities and soil C, N, and P levels. Cropping systems included continuous sorghum(Sorghum bicolor L.), cotton(Gossypium hirsutum L.), corn(Zea mays L.), and cotton/sorghum rotations after 26 years of treatment imposition. Soil under continuous sorghum and continuous corn had 15% and 11%, respectively, greater C concentrations than soil under continuous cotton.Organic C was 10% higher at 0–7.5 cm than at 7.5–15 cm. Total N followed similar trends with soil depth as organic C. Continuous sorghum had 19% higher total N than other crop species and rotations. With fertilization, continuous cotton had the highest total P at 0–7.5 cm and sorghum had the highest at 7.5–15 cm. Soil total P was 14% higher at 0–7.5 than at 7.5–15 cm, and fertilization increased 15% total P compared to unfertilized soil. Arylsulfatase, alkaline phosphatase, and β-d-glucosidase activity were the highest for sorghum and the lowest for cotton. Rotation increased enzyme activities compared to continuous cotton but not for continuous sorghum. Of all crop species and rotations, continuous cotton generally showed the lowest levels of organic matter and enzyme activities after 26 years. Fertilization significantly increased the yields for all cropping systems, but rotation had no significant effect on either sorghum or cotton lint yield compared to each crop grown in monoculture. Long-term cropping did not increase soil organic matter levels beyond short-term gains, indicating the difficulty in promoting C sequestration in subtropical soils.
