微观世界
土壤水分
单作
土壤碳
溶解有机碳
底土
农学
土壤有机质
化学
环境科学
总有机碳
环境化学
土壤科学
生物
作者
B. John,Bernard Ludwig,Heiner Flessa
标识
DOI:10.1016/s0038-0717(03)00180-9
摘要
Understanding carbon dynamics in soil is the key to managing soil organic matter. Our objective was to quantify the carbon dynamics in microcosm experiments with soils from long-term rye and maize monocultures using natural 13C abundance. Microcosms with undisturbed soil columns from the surface soil (0–25 cm) and subsoil (25–50 cm) of plots cultivated with rye (C3-plant) since 1878 and maize (C4-plant) since 1961 with and without NPK fertilization from the long-term experiment ‘Ewiger Roggen’ in Halle, Germany, were incubated for 230 days at 8 °C and irrigated with 2 mm 10−2 M CaCl2 per day. Younger, C4-derived and older, C3-derived percentages of soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass (Cmic) and CO2 from heterothropic respiration were determined by natural 13C abundance. The percentage of maize-derived carbon was highest in CO2 (42–79%), followed by Cmic (23–46%), DOC (5–30%) and SOC (5–14%) in the surface soils and subsoils of the maize plots. The percentage of maize-derived C was higher for the NPK plot than for the unfertilized plot and higher for the surface soils than for the subsoils. Specific production rates of DOC, CO2-C and Cmic from the maize-derived SOC were 0.06–0.08% for DOC, 1.6–2.6% for CO2-C and 1.9–2.7% for Cmic, respectively, and specific production rates from rye-derived SOC of the continuous maize plot were 0.03–0.05% for DOC, 0.1–0.2% for CO2-C and 0.3–0.5% for Cmic. NPK fertilization did not affect the specific production rates. Strong correlations were found between C4-derived Cmic and C4-derived SOC, DOC and CO2-C (r≥0.90), whereas the relationship between C3-derived Cmic and C3-derived SOC, DOC and CO2-C was not as pronounced (r≤0.67). The results stress the different importance of former (older than 40 years) and recent (younger than 40 years) litter C inputs for the formation of different C pools in the soil.
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