A comparison of the effects of Lotus and white clover on some nutrient cycling factors

Abstract

In a laboratory test, nitrification rates were lower in soil incubated with dried Lotus herbage than in the same soil incubated with white clover herbage. Nitrification rates in soil amended with dried Lotus herbage were higher in soil that had grown Lotus for the previous three years, than in soil that had only one year in Lotus. This was interpreted as evidence for progressive selection for soil microorganisms that can readily decompose Lotus. This conclusion was supported by observation of rapid availability of nitrogen from Lotus herbage and dung when they were added to a hill soil that had grown Lotus for at least 6 years. Field sampling showed higher earthworm numbers under white clover pasture, than under Lotus pasture or ryegrass pasture, which had the lowest number. Dung from animals grazing Lotus pasture was incorporated more rapidly by earthworms than dung from white clover or ryegrass pastures, in laboratory and field experiments. This demonstrated preferences by earthworms among dungs derived from different pasture species. Further work is required to determine the effects on nutrient cycling processes of the different dung incorporation rates that were measured. Keywords: condensed tannins, earthworms, Lotus, nitrogen, nutrient cycling, soil micro-organisms, white clover