Soil organic carbon （C） and total nitrogen （N） pools of a Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） （CF） forest, and an evergreen broadleaf （EB） forest located in mid-subtropical, southeastern Ch...Soil organic carbon （C） and total nitrogen （N） pools of a Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） （CF） forest, and an evergreen broadleaf （EB） forest located in mid-subtropical, southeastern China, were compared before clearcutting, with the effect of slash burning on organic C and total N in the top 10 cm of soil before and after burning also being evaluated. Prior to clearcutting CF forest had significantly lower （P 〈0.05） organic C and total N in the soil （0-100 cm） compared to EB forest with approximately 60% of the C and N at the two forest sites stored at the 0 to 40 cm soil. In post-burn samples of the 0-10 cm depth at 5 days, 1 year, and 5 years for CF and EB forests, significantly lower levels （P 〈0.05） of organic C and total N than those in the pre-burn samples were observed. Compared to the pre-burn levels, at post-burn year 5, surface soil organic C storage was only 85% in CF forest and 72% in EB forest, while total N storage was 77% for CF forest and 73% for EB forest. Slash burning caused marked long-term changes in surface soil C and N in the two forest types.展开更多
Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged c...Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged conditions. Greater amounts of C and N from azolla were retained in soils throughout the 10-year experimental period compared to those from the other plant materials. The residual C Of all the plant materials in the two soils under upland conditions mineralized st rates corresponding to half-lives between 4.4-6.6 years,while the corresponding figures for thine under submerged conditions were between 6.5-13.1 years. Minerallization of residual organic N followed the same pattern as residual C. Compared to residual C, however, the mineralization rates of residual organic N in most cases were significantly lower and the percentages of added N regained in sons were higher. More N from plat materials was retained in the yellow-brown soil than in the red soil, but no consistent differences in the amounts of C from plant materials and in the mineralization rates of both residual C and residual organic N between the two soils could be found.展开更多
Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the s...Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon（SOC）, total nitrogen（TN）, microbial biomass carbon（MBC）, microbial biomass nitrogen（MBN） and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site（3700 m to 4300 m area） in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon（SMBC） and soil microbial biomass nitrogen（SMBN）were positively correlated with SOC. The content of easily oxidized carbon（EOC）, particulate organic carbon（POC） and light fraction organic carbon（LFOC） decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth.The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents weredifferent with the changes of SOC（p＆lt;0.05）,meanwhile, both LFOC and POC were related to total SOC（p＆lt;0.05）. The physical and chemical properties of soil, including temperature, humidity, and altitude,were involved in the regulation of SOC, TN, MBC,MBN and LFOC contents in the Sygera Mountains,Tibetan Plateau.展开更多
The use of plant materials as soil amendments is an uncommon practice amongst major farming communities in Ghana, although it is necessary for soil fertility improvement. An examination of the effects of soil amendmen...The use of plant materials as soil amendments is an uncommon practice amongst major farming communities in Ghana, although it is necessary for soil fertility improvement. An examination of the effects of soil amendments is necessary to encourage the use of under-utilized organic resources in Ghana. Thus, a field experiment was conducted using 8 different tropical plant materials mixed with chicken manure as soil amendments for growth of tomato as a test crop. The plant materials included Leucaena leueocephala, Centrosema pubescens, Sesbania sesban, Gliricidia sepium, Mucuna pruriens, Pueraria phaseoloides, Azadirachta indiea, and Theo- broma cacao. There were two other treatments： one with equivalent amounts of chemical fertilizers and the other with no-fertilizer input （control）. Plant materials were mixed with chicken manure to obtain a uniform carbon-to-nitrogen （C：N） ratio of 5：1. Except the no-fertilizer control, all treatments received the same amount of nitrogen （N）. To clarify the decomposition pattern of the plant materials in soil, an incubation experiment was conducted using only the plant materials before the field experiment. The Glirieidia treatment released significantly more mineral N than the other plant materials in the incubation experiment. However, the tomato fruit yield was not enhanced in the Gliricidia treatment in the field experiment. The known quality parameters of the tested plant materials, such as total N, total carbon （C）, C：N ratio, and total polyphenols, had minimal effects on their mineralization dynamics. Azadirachta showed the best synergistic effect with chicken manure through significantly increasing soil microbial biomass and fruit yield of tomato. This result provides insights into the possible adoption of Azadirachta in combination with chicken manure as a soil amendment in small-scale agricultural holdings.展开更多
It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effe...It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30170770).
文摘Soil organic carbon （C） and total nitrogen （N） pools of a Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） （CF） forest, and an evergreen broadleaf （EB） forest located in mid-subtropical, southeastern China, were compared before clearcutting, with the effect of slash burning on organic C and total N in the top 10 cm of soil before and after burning also being evaluated. Prior to clearcutting CF forest had significantly lower （P 〈0.05） organic C and total N in the soil （0-100 cm） compared to EB forest with approximately 60% of the C and N at the two forest sites stored at the 0 to 40 cm soil. In post-burn samples of the 0-10 cm depth at 5 days, 1 year, and 5 years for CF and EB forests, significantly lower levels （P 〈0.05） of organic C and total N than those in the pre-burn samples were observed. Compared to the pre-burn levels, at post-burn year 5, surface soil organic C storage was only 85% in CF forest and 72% in EB forest, while total N storage was 77% for CF forest and 73% for EB forest. Slash burning caused marked long-term changes in surface soil C and N in the two forest types.
文摘Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged conditions. Greater amounts of C and N from azolla were retained in soils throughout the 10-year experimental period compared to those from the other plant materials. The residual C Of all the plant materials in the two soils under upland conditions mineralized st rates corresponding to half-lives between 4.4-6.6 years,while the corresponding figures for thine under submerged conditions were between 6.5-13.1 years. Minerallization of residual organic N followed the same pattern as residual C. Compared to residual C, however, the mineralization rates of residual organic N in most cases were significantly lower and the percentages of added N regained in sons were higher. More N from plat materials was retained in the yellow-brown soil than in the red soil, but no consistent differences in the amounts of C from plant materials and in the mineralization rates of both residual C and residual organic N between the two soils could be found.
基金supported by CFERN & GENE Award Funds on Ecological Paper
文摘Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon（SOC）, total nitrogen（TN）, microbial biomass carbon（MBC）, microbial biomass nitrogen（MBN） and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site（3700 m to 4300 m area） in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon（SMBC） and soil microbial biomass nitrogen（SMBN）were positively correlated with SOC. The content of easily oxidized carbon（EOC）, particulate organic carbon（POC） and light fraction organic carbon（LFOC） decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth.The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents weredifferent with the changes of SOC（p＆lt;0.05）,meanwhile, both LFOC and POC were related to total SOC（p＆lt;0.05）. The physical and chemical properties of soil, including temperature, humidity, and altitude,were involved in the regulation of SOC, TN, MBC,MBN and LFOC contents in the Sygera Mountains,Tibetan Plateau.
文摘The use of plant materials as soil amendments is an uncommon practice amongst major farming communities in Ghana, although it is necessary for soil fertility improvement. An examination of the effects of soil amendments is necessary to encourage the use of under-utilized organic resources in Ghana. Thus, a field experiment was conducted using 8 different tropical plant materials mixed with chicken manure as soil amendments for growth of tomato as a test crop. The plant materials included Leucaena leueocephala, Centrosema pubescens, Sesbania sesban, Gliricidia sepium, Mucuna pruriens, Pueraria phaseoloides, Azadirachta indiea, and Theo- broma cacao. There were two other treatments： one with equivalent amounts of chemical fertilizers and the other with no-fertilizer input （control）. Plant materials were mixed with chicken manure to obtain a uniform carbon-to-nitrogen （C：N） ratio of 5：1. Except the no-fertilizer control, all treatments received the same amount of nitrogen （N）. To clarify the decomposition pattern of the plant materials in soil, an incubation experiment was conducted using only the plant materials before the field experiment. The Glirieidia treatment released significantly more mineral N than the other plant materials in the incubation experiment. However, the tomato fruit yield was not enhanced in the Gliricidia treatment in the field experiment. The known quality parameters of the tested plant materials, such as total N, total carbon （C）, C：N ratio, and total polyphenols, had minimal effects on their mineralization dynamics. Azadirachta showed the best synergistic effect with chicken manure through significantly increasing soil microbial biomass and fruit yield of tomato. This result provides insights into the possible adoption of Azadirachta in combination with chicken manure as a soil amendment in small-scale agricultural holdings.
基金supported by the Venezuelan Institute for Scientific Research to the first author
文摘It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.
