The problems of standardization of methods in use in microbiological soil research
Netherlands Journal of Agricultural Science
A symposium organized by the International Association of Soil Science, Commission III -Soil Biology, was held at Louvain from 3 to 5 June 1957. The subject of this symposium was a discussion of the methods used in soil microbiology, the ultimate object being to tandardize the methods used in various laboratories. The subjects discussed were presented in a number of general reports, viz. : 1 the sampling of soils (ZIEMIECKA, Pologne), 2 the determination of biological activity (MISHOUSTINE,
... y (MISHOUSTINE, U.R.S.S.), 3 the study and counting of soil bacteria (POCHON, France), 4 the study and counting of soil fungi (VERONA, Italy and SIMONART, Bel gium), and 5 a report on the descriptive chart of standard methods used in the bio logical examination of the soil to be given by the present author. I felt my task was rather an onerous one, especially as I believe that stan dardization in so complex a subject as soil microbiology is impracticable in view of our present knowledge. A great deal of research will have to be done before standard methods are acceptable. The biological activity of the soil is substantially of an enzymatic kind, the enzymes being produced by the living microflora and fauna. Hence the num bers of micro-organisms and their activity determine the biological activity of the soil. The factors mentioned depend on the fertility of the soil. Soil fertility in its turn is a very complex conception. In its most simple form we may regard it as the property of the soil to produce a crop, the most fertile soil being that which produces the largest crop for the least outlay and labour. The factors that determine fertility are numerous. We may mention, for example, the texture of the soil, which determines the interdependent rates of the 3 soil phases : solid substance, liquid, and gas, and which in turn depends on the soil colloids, both organic and inorganic. The colloidal soil complex is at the same time a most important factor for the presence and availibility of plant nutrients ; it controls the buffering capacity against acid and alkali and regulates the fluctuations in pH. It is the task of the farmer to maintain a good texture. Good maintenace will do a great deal ; regular dressings of organic matter will nearly always be neces sary. Abnormal maintenance will lead to abnormal composition of the micro biological activity in the soil. For us this means that a descriptive chart should include standardized methods for estimating soil texture, water capacity, pH and buffering capacity.