Determinations of parameters on soil biological activities: V. Complex interactions between test factors and experimental variants

Abstract

Summary In this 5th and last information on a series for determination of soil micro-biological activity parameters, complex studies — in dependence of the results reported in the former publications — on the interaction between the test factors: oats yield, Aspergillus niger growth, bacterial, actinomycetes, and fungal population, soil respiration, fermenting activity, and crumble stability were carried through with three steps each in the following test variants: soil, water level, temperature level, rate of fertilizing, degree of humus, pH stage, and seasons. With the first discussed reaction standards of the test factors with regard to the steps of the trial variants it could be demonstrated that the differentiating influence of water level, soil, and temperature level is especially high in all the test factors. Less distinct was the differentiating influence of the trial variants seasons, pH, degree of humus, and rates of fertilizing. Attention is called to some peculiarities. This discussion was followed by the investigation of the parallel or opposite, positive or negative deviations from the experimental mean value in the order of the results according to the three steps of the trial variants; here the probable edaphic cause is considered. Several ways of behaviour, up to now considered isolated only, could now be explained in a complex manner. Further, the repeatedly raised question of a possible interrelation between the plant yield of the soil (soil fertility) and its micro-biological activity was investigated by comparing the obtained oats yield on each step of the respective trial variant with the micro-biological results achieved in this study. Here it is evidenced that all the examined soil micro-biological characteristics — as well as the oats yield — were improved by the intensity of fertilizing. Also the relation with the humus content steps is analogous to a high degree. All the other environmental influences give evidence of specific interactions, partly in the same direction, partly opposite, between oats yield and activity for the soil micro-organisms. Of the micro-biological test factors shows the growth of Aspergillus niger the greatest similarity to the oats yield (Aspergillus test according to NIKLAS). Finally, the complex interactions between the characteristics of ecological site and biological activity of a soil are grouped in a simplified manner in a tabulated arrangement for practical purposes as “activity expectation”.