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I T HAS been observed frequently that the productivity and quality of pasture and meadow mixtures degenerate with time. This degeneration is often associated with low production or depletion of legumes in the mixtures. Additional knowledge concerning the inter-relationships of physiological and ecological factors to the productivity and maintenance of legumes is of paramount importance.The productivity of leguminous plants in mixtures with grasses is known to be influenced by cultural, climatic, and biological factors. Since plant species do not react the same to a given combination of these factors, changes in the species which make up plant associations are characteristically of a dynamic nature. The species which tend to dominate in a given plant mixture are those that are affected most favorably by the imposed and natural factors which influence the ~rowth rate. Plan of ExperimentsEXPERIMENT I It has been established that luxury consumption of potassium oc~;urs with grasses as well as with legumes. The possibility exists, therefore, that luxury consumption of potassium by an associate species early in the year when the potassium supply is relatively high might result in definite competition for potassium later in the season.In order to investigate this problem an experiment was set up on an established Ladino clover-grass association. The effects of mixtures of nitrogen and potassium fertilizers on aftermath growth and nutrient uptake by the species were determined.The experimental site chosen was in its fourth production year and the productivity of the herbage was low. Originally, the area had been sown with a mixture of Ladino. red clover, alfalfa, and timothy. At the time the initial fertilizer applications were made, however, the herbage consisted of approximately 60o/o timothy, 20% Kentucky bluegrass, 10% quack grass, 5% Ladino clover, and 5% weeds. The herbage was cut for silage in June 1947 after which the following fertilizer treatments were applied on the surface.

LANTS receive metabolic energy through the action of P sunlight in the photosynthetic process. The rate of accu-