Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,t...Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.Therefore,a four-year (2015–2018) field experiment was conducted with four levels (i.e.,0,6,12and 18 Mg ha~(–1)) of straw returned as an interlayer.Compared with no straw interlayer (CK),straw addition increased SOC concentration by 14–32 and 11–57%in the 20–40 and 40–60 cm soil layers,respectively.The increases in soil TN concentration (8–22 and 6–34%in the 20–40 and 40–60 cm soil layers,respectively) were lower than that for SOC concentration,which led to increased soil C:N ratio in the 20–60 cm soil depth.Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm),which promoted uniform distributions of SOC and TN in the soil profile.Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.Generally,compared with other treatments,the application of 12 Mg ha~(–1) straw had higher SOC,TN and C:N ratio,and lower soil stratification ratio in the2015–2017 period.The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years,and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.展开更多
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
Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total ni...Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.展开更多
Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incom...Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.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
Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20...Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20,25,30,35 and 40]on apple growth and nitrogen utilization and loss by using15N trace technique. The results showed that,with the increasing of soil C/N ratio,apple shoot length and fresh weight increased at first,and then decreased; the higher apple shoot length and fresh weight appeared in C/N = 15,20 and 25 treatments,and there were no significant differences among these three treatments,but significantly higher than the other treatments. Statistical analysis revealed that there was significant difference in nitrogen utilization rate between the different treatments,the highest N utilization rate was occurred in soil C/N = 25 treatment which value was 22. 87%,and there was no significant difference between soil C/N = 25 and C/N = 20 treatments,but both the two treatments were significantly higher than the other treatments; Soil C/N = 40 had the lowest N utilization rate which value was 15. 43%,and this value was less than CK( 16. 65%). The proportion of plant absorption nitrogen from fertilizer was much higher when the value of soil C/N ratio in the range of 15- 25,but the percentage of plant absorption nitrogen from soil was much higher when the soil C/N ratio was too low( < 15) or high( < 25). Amount of residual nitrogen in soil increased gradually with the soil C/N ratio increasing,the amount of residual nitrogen in C/N = 40 treatment was 1. 32 times than that in CK. With the increasing of soil C/N ratio,fertilizer nitrogen loss decreased at first,and then increased,fertilizer nitrogen loss was the minimum in C/N = 25 treatments( 49. 87%) and the maximum were occurred in CK( 61. 54%). Therefore,regarding the apple growth and nitrogen balance situation,the value of soil C/N ratio in the range of 15- 25 would be favorable for apple growth and could increase effectively nitrogen fixed by soil,reduce nitrogen loss,and improve the nitrogen utilization ratio.展开更多
The effect of Ti(C,N) on properties of low-carbon MgO-C bricks was investigated.The phase composition and the microstructure of the matrix of low-carbon MgO-C brick containing Ti(C,N) were studied by XRD and SEM analy...The effect of Ti(C,N) on properties of low-carbon MgO-C bricks was investigated.The phase composition and the microstructure of the matrix of low-carbon MgO-C brick containing Ti(C,N) were studied by XRD and SEM analysis together with EDS.The results showed that Ti(C,N) distributed in the matrix of low-carbon MgO-C brick uniformly after being treated at 1 600 ℃ for 3 h in coke powder bed,and Ti(C,N) and MgO formed a solid solution.After the treatment at 1 600 ℃ for 3 h in coke powder bed,the bulk density and cold crushing strength of low-carbon MgO-C brick with Ti(C,N) decreased,and the apparent porosity and linear change rate of specimens increased.The oxidation resistance of low-carbon MgO-C brick with Ti(C,N) was superior to that of low-carbon MgO-C brick with no additives,but inferior to that of low-carbon MgO-C brick with Al powder.The slag resistance of the specimen with Ti(C,N) was excellent as well.展开更多
基金funded by the National Natural Science Foundation of China (31871584)the Agricultural Science and Technology Innovation Program, Chinese Academy of Agricultural Sciences (CAAS-ZDRW202201)+2 种基金the Fundamental Research Funds for Central Non-profit Scientific Institution, China (1610132020011)the “Open the list” in charge of the Science and Technology Project of Ordos, Center for Agro-pastoral Ecology and Resource Conservation of Ordos City, Inner Mongolia, China (JBGS2021-001)the Inner Mongolia Autonomous Region Research Project (2021EEDSCXSFQZD011)。
文摘Soil salinization is a critical environmental issue restricting agricultural production.Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress.However,the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive.Therefore,a four-year (2015–2018) field experiment was conducted with four levels (i.e.,0,6,12and 18 Mg ha~(–1)) of straw returned as an interlayer.Compared with no straw interlayer (CK),straw addition increased SOC concentration by 14–32 and 11–57%in the 20–40 and 40–60 cm soil layers,respectively.The increases in soil TN concentration (8–22 and 6–34%in the 20–40 and 40–60 cm soil layers,respectively) were lower than that for SOC concentration,which led to increased soil C:N ratio in the 20–60 cm soil depth.Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm),which promoted uniform distributions of SOC and TN in the soil profile.Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield.Generally,compared with other treatments,the application of 12 Mg ha~(–1) straw had higher SOC,TN and C:N ratio,and lower soil stratification ratio in the2015–2017 period.The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years,and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.
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Under the auspices of the National Natural Science Foundation of China (No. 40171053)
文摘Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.
文摘Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.
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.
基金Special Fund for Agro-scientific Research in the Public Interest(201103003)the Earmarked Fund for China Agriculture ResearchSystem(CARS-28)
文摘Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20,25,30,35 and 40]on apple growth and nitrogen utilization and loss by using15N trace technique. The results showed that,with the increasing of soil C/N ratio,apple shoot length and fresh weight increased at first,and then decreased; the higher apple shoot length and fresh weight appeared in C/N = 15,20 and 25 treatments,and there were no significant differences among these three treatments,but significantly higher than the other treatments. Statistical analysis revealed that there was significant difference in nitrogen utilization rate between the different treatments,the highest N utilization rate was occurred in soil C/N = 25 treatment which value was 22. 87%,and there was no significant difference between soil C/N = 25 and C/N = 20 treatments,but both the two treatments were significantly higher than the other treatments; Soil C/N = 40 had the lowest N utilization rate which value was 15. 43%,and this value was less than CK( 16. 65%). The proportion of plant absorption nitrogen from fertilizer was much higher when the value of soil C/N ratio in the range of 15- 25,but the percentage of plant absorption nitrogen from soil was much higher when the soil C/N ratio was too low( < 15) or high( < 25). Amount of residual nitrogen in soil increased gradually with the soil C/N ratio increasing,the amount of residual nitrogen in C/N = 40 treatment was 1. 32 times than that in CK. With the increasing of soil C/N ratio,fertilizer nitrogen loss decreased at first,and then increased,fertilizer nitrogen loss was the minimum in C/N = 25 treatments( 49. 87%) and the maximum were occurred in CK( 61. 54%). Therefore,regarding the apple growth and nitrogen balance situation,the value of soil C/N ratio in the range of 15- 25 would be favorable for apple growth and could increase effectively nitrogen fixed by soil,reduce nitrogen loss,and improve the nitrogen utilization ratio.
文摘The effect of Ti(C,N) on properties of low-carbon MgO-C bricks was investigated.The phase composition and the microstructure of the matrix of low-carbon MgO-C brick containing Ti(C,N) were studied by XRD and SEM analysis together with EDS.The results showed that Ti(C,N) distributed in the matrix of low-carbon MgO-C brick uniformly after being treated at 1 600 ℃ for 3 h in coke powder bed,and Ti(C,N) and MgO formed a solid solution.After the treatment at 1 600 ℃ for 3 h in coke powder bed,the bulk density and cold crushing strength of low-carbon MgO-C brick with Ti(C,N) decreased,and the apparent porosity and linear change rate of specimens increased.The oxidation resistance of low-carbon MgO-C brick with Ti(C,N) was superior to that of low-carbon MgO-C brick with no additives,but inferior to that of low-carbon MgO-C brick with Al powder.The slag resistance of the specimen with Ti(C,N) was excellent as well.
