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Agronomy Journal Abstract -

Effects of N and Seeding Rate on Grass-Legume Mixtures on Coal Mine Spoils: Biomass Production, Soil Factors, and N2 Fixation1


This article in AJ

  1. Vol. 76 No. 6, p. 895-900
    Received: Sept 22, 1983

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  1. K. Yamanaka and
  2. F. B. Holl2



The importance of N2-fixing legume species in colonization and the development of stable ecosystems on reclaimed mineral spoils has long been recognized. In greenhouse experiments on coal mine spoils some of the factors affecting early plant performance have been evaluated. Applied N was rapidly taken up by plants or leached from the spoil material, such that N would be a limiting factor under similar field conditions. Total biomass production increased with increasing grass seeding rates and at high N fertility while N2 fixation was depressed at higher grass seeding rates and with high N fertility. In the same treatments, a significant (P < 0.01) grass − fertilizer interaction was reflected by an observed decrease in legume biomass. Changes in aboveground total biomass and N2 fixation were related to changes in the legume component and were largely independent of soil N. Optimum biomass production and N2-fixing activity were obtained by a treatment combination of 17.5 kg/ha grasses, 30 kg/ha legumes, and 50 kg/ha N.

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