The efficiency of collecting soil arthropods from the froth by flotation method at different intervals of counting

Abstract

The importance of the accurate estimation of soil organisms in the ecosystem has been emphasised by the International Biological Programme for productivity studies. Hence the method for a precise estimation of soil fauna receives greater attention. In an extensive study Edwards and Fletcher (1970) stated that no single method was ideal for all groups of soil invertebrates. Singh and Sharma (in prep.) studied the comparative efficacy of flotation method and Tullgren funnel and concluded that the former was much more efficient then the latter especially in the case of arable soil with lower organic matter content. Macfadyen(1962) also showed the distinct advantages of flotation method for arthropod extraction. In quantitative studies larger sample units will give more accurate data and these can be easily processed with the flotation method. Another advantage is that the quiescent stages of arthropods can also be extracted by flotation technique as this method is not dependent on the behavioural characteristics of soil arthropods. Mukharji and Singh (1970) and again Singh and Mukharji (1971) successfully used flotation method for extraction of soil arthropods in their studies. The present authors tried Tullgren funnels but failed to obtain satisfactory results from the soil at Varanasi (India) which is sandy loam and very poor in organic content (O.M. 0.5 — 1.26%). The number of micro-arthropods obtained from Tullgren funnels was considerably lower and as such it had to be abandoned and the flotation method had to be resorted to.