Inhibition of nitrifiers by grass root extracts.

Published online
28 Aug 1967
Content type
Journal article
Journal title
Journal of Applied Ecology

Munro, P. E.

Publication language
Africa South of Sahara & Southern Africa


Extracts of the roots of Hyparrhenia filipéndula and other grasses were tested against soil enrichment cultures of NH3-and NO2 oxidizers, by measuring nitrite production or consumption during short incubations. The roots of H. filipéndula contained a water-soluble heat-labile dialysable substance which inhibited nitrifying bacteria. Water extracts of these roots quickly lost their inhibitory activity when stored in a refrigerator under aseptic conditions; alcohol extracts contained inhibitors which appeared to be heat stable. Other common grass species of the Rhodesian Highveld also contained a heat-labile, water-soluble inhibitor. The water, in which roots of Eragrostis curvula roots had been growing for three weeks, contained a heat-labile inhibitor. Results do not oppose earlier suggestions that changes in availability of mineral N in soil are due to inhibition of nitrification by grass root exudates.

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