Nutrient competition in plant associations
1950
Blaser, R.E. | Brady, N.C.
Experiments were designed to ascertain the effects of nitrogen and potassium fertilization on the productivity and botanical and chemical composition of Ladino clover and nonlegumes when grown in a mixture. Potassium fertilization stimulated the growth of Ladino clover, but did not directly affect the productivity of the nonleguminous plants in the association. The potassium content of all species in the mixture was increased as the potash application was increased. The chemical composition of the species differed, the grasses being higher in potassium content than the legumes and the weeds higher than the grasses. Nitrogen fertilizers increased the growth of grasses and decreased growth of the leguminous plants in a mixed association. As the growth of grasses was increased by nitrogen fertilization the amount of potassium removed by the grasses was increased. Hence, the concurrent and/or after-effect of nitrogen on reducing the leguminous associate was attributed to competition for potassium. Evidence that there is competition among the species for potassium is shown by the following: (1) High productivity of grasses in the first harvest after nitrogen fertilization did not reduce the growth of Ladino clover. In subsequent harvests where grass yields were similar the after-effect of nitrogen fertilization showed reduced clover yields. This was attributed to high potassium removal by the nonlegumes. (2) Nitrogen fertilization reduced the Ladino clover yields less with the higher application of potash than with the lower rate. The application of potassium nutrient competition to plant succession, desirable genotypes, and maintenance of leguminous plants is discussed.
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