Interference from plant roots in the estimation of soil microbial ATP, C, N and P

• Published in: Soil biology & biochemistry 1985, Vol.17 (3), p.275-278
• Main Authors: Sparling, G.P., West, A.W., Whale, Karina N.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Lolium perenne; measurement; Microbial ecology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; roots; Soil; soil chemistry; soil organic matter; Soil science; Zea mays
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(85)90060-4

Excised, solution-grown roots of maize or ryegrass added to two pasture soils at the rate of 6.0mg g −1 and 13.8 mg g −, respectively, increased the flush (fumigated minus control values) of CO 2-C by up to 1.89-fold, KCl extractable N by up to 1.88-fold, and NaHCO 3 extractable P by 3.28-fold. The ATP content of the soil was increased by up to 1.42-fold. Because of high variability the effect of the roots on the C and N flushes was not significant at P < 0.05. Incubation of the root-amended soils for 7 days at 25°C prior to fumigation much decreased the contribution from the roots to the C and N flush, and to the ATP content. There was, however, still a large significant effect of the roots on the P-flush, this being up to 3 times greater than the equivalent soil without roots. In soil samples with a high viable root density (> 6mg g −1) such as may occur in dense pastures, greenhouse pot experiments or rhizosphere soil samples, it is recommended that they be incubated for 7 days prior to fumigation and analyses. Without such prior incubation there is the risk that root material may be included in the “microbial” biomass estimations.