Inhibition of nitrifiers by grass root extracts.
Roots of Hyparrhenia filipéndula contained a water-soluble, heat-labile and dialysable substance which inhibited nitrifying bacteria. Alcohol extracts of the roots also contained inhibitors which were apparently not heat-labile. Evidence was found that a heat-labile inhibitor may be excreted by Eragrostis curvula roots in water culture. [See also H.A. 36: 477.]-R.B.