Humus accumulation and microbial activities in calcari-epigleyic fluvisols under grassland and forest diked in for 30 years [An article from: Soil Biology and Biochemistry]

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Description:
The accumulation and transformation of organic matter during soil development is rarely investigated although such processes are relevant when discussing about carbon sequestration in soil. Here, we investigated soils under grassland and forest close to the North Sea that began its genesis under terrestrial conditions 30 years ago after dikes were closed. Organic C contents of up to 99mgg^-^1 soil were found until 6cm soil depth. The humus consisted mainly of the fraction lighter than 1.6gcm^-^3 which refers to poorly degraded organic carbon. High microbial respiratory activity was determined with values between 1.57 and 1.17@mg CO"2-Cg^-^1 soil h^-^1 at 22^oC and 40 to 70% water-holding capacity for the grassland and forest topsoils, respectively. The microbial C to organic C ratio showed values up to 20mg C"m"i"cg^-^1 C"o"r"g. Although up to 2.69kg Cm^-^2 were estimated to be sequestered during 30 years, the microbial indicators showed intensive colonisation and high transformation rates under both forest and grassland which were higher than those determined in agricultural and forest topsoils in Northern Germany.