Hot-water-soluble C as a simple measure of labile soil organic matter: The relationship with microbial biomass C

• Published in: Soil biology & biochemistry 1998-09, Vol.30 (10), p.1469-1472
• Main Authors: Sparling, G, Vojvodić-Vuković, Maja, Schipper, L.A
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(98)00040-6

Many monitoring programs advocate that soil organic matter contents should be measured to assess effects of land use on soil quality. Rates of change in the total organic pool are relatively slow and other more labile soil C pools, such as soil microbial C, have been suggested as more sensitive indices to monitor longer-term trends in organic matter. The fumigation-extraction methods to determine microbial C are relatively complex and time-consuming, which could limit their inclusion in routine monitoring programs. In contrast, water extracts of moist and air-dried soils are simple to obtain and can provide a labile C fraction. Cold-water extracts from moist soil contain very little C derived from microbial cells, and there is poor agreement between the microbial biomass C and amounts of soluble C extracted from moist soils. However, extracts from dried, fumigated or partially-sterilized soil contain much greater amounts of soluble C, some of which is derived from killed microbial cells used soil desiccation as an alternative to fumigation to release microbial C and, on a very limited range of soils, Sikora et al. found good agreement between microbial biomass measured by the desiccation method, by fumigation-extraction or the substrate-induced respiration methods.