Assessment of Methods for Measuring Soil Microbial Biomass Carbon in Temperate Fruit Tree-Based Ecosystems

ABSTRACT

We investigated the potential of three methods of quantifying microbial biomass carbon (MBC), viz., chloroform fumigation-extraction (CFE) following organic C estimation through Vance method (CFE-V) and Snyder–Trofymow method (CFE-ST), and substrate-induced respiration (SIR) method in soils under various temperate fruit crops along with a control (no plantation) at 0–20 and 21–40 cm soil depths. CFE methods have shown significant (p < 0.05) increase in chloroform labile C in all orchards over the control in surface soil. The interaction between the fruit crops and methods, although significant (p < 0.01), indicated that CFE-ST and SIR methods were statistically at par with each other within the same fruit crop, except peach plantation (CEF-ST significantly lower than SIR) in 0–20 cm soil depth. The coefficient of variation recorded for chloroform labile organic C estimates by CFE-ST method makes it more precise than CFE-V method, especially in 0–20 cm soil depth. The very close agreement between the methods suggests that over this narrower range (i.e., smaller geographical area) all methods are appropriate for assessing MBC. However, SIR, being most sensitive to orchard plantations and strongly correlated with various soil chemical properties, could preferably be recommended for estimation of MBC in such soils. As an alternative to CFE-V method, CFE-ST may also be used for estimation of chloroform labile organic C in these soils.

KEYWORDS:

• Microbial biomass C
• methods
• soil depth
• temperate fruit crops

Acknowledgments

This research work was carried out under “Professional Attachment Training” as a part of the revised module of FOCARS training, and for that the authors are thankful to Indian Council of Agricultural Research (ICAR), New Delhi. The help and support provided by Dr. S.C. Kaushik throughout the study is also gratefully acknowledged. The first author is also grateful to Prof. Nazeer Ahmed and Dr. Sarvendra Kumar for their effort. Thanks to the anonymous reviewer for the critical remarks and suggestions on this article.