Influence of macroclimate on soil microbial biomass

• Published in: Soil biology & biochemistry Vol. 21; no. 2; pp. 211 - 221
• Main Authors: Insam, H., Parkinson, D., Domsch, K.H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1989; New York, NY Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; 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; Organic carbon; Climate; Organic matter; Long term test; United States; Cropping system; Evaporation; North America; Microbial biomass; Field experiment; Canada; Soils; Crop rotation; America; Atmospheric precipitation
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(89)90097-7

Soils from 12 agricultural long-term experimental fields located in contrasting climatic regions were used to assess the influence of macroclimate on soil microbial biomass (C micr). C micr was measured using the substrate-induced respiration technique. When C micr was calculated on the basis of soil dry mass (mg C micr g −1 soil d.m.), only poor correlations with climatic variables were found. However, when C micr was calculated based on organic carbon (mg C micr g −1 C org), close relationships with climatic variables were found. Especially, integrative climatic variables which reflected not only the temperature regime but also the moisture conditions, were found to be good predictors of the C micr-to-C org ratio. The best predictor was the precipitation-evaporation quotient which accounted for 68% of the variance. With a stepwise, multiple-linear regression procedure, the clay content and pH of the soils were found to account for another 2 and 3% of the variance, respectively. Parts of the remaining variance could be accounted for by differences in fertilization, crops, tillage practices or residue returns. The C micr-to-C org ratio of monocultures was significantly lower than that of crop rotations, and so was that of mineral fertilized compared to organically manured plots. The organic matter content of the soils studied were at or near the equilibrium level. An equilibrium function for the C micr-to-C org ratio was calculated: y = 18.18+ 108.3-e −6.728 x , where x = precipitation/ evaporation. Deviation from this equilibrium line would indicate that a certain soil is losing or accumulating organic matter.