Biotic factors include grazing pressure, disease, and insects. Managing a pasture ecosystem requires balancing both abiotic and biotic factors. If these factors fall out of balance, desirable forage species are lost and replaced by less or undesirable ones such as broomsedge. At these soil fertility levels, desirable forage species will not survive under grazing and haying pressure. As a desirable forage plant dies, it leaves a void in the canopy, allowing additional light to penetrate the canopy and setting up an environment suitable for the germination and propagation of broomsedge.
Close grazing adds to the problem.
Grazing animals avoid eating broomsedge. This means desired grasses and legumes are being nipped off every seven or eight days. This shifts the environmental factors in favor of the broomsedge. Broomsedge is not competitive in a well-managed pasture. Begin with a simple soil test.