Factors Involved in the Decline of Annual Ryegrass Seeded on Burned Brushlands in California

Abstract

The effect of amount of mulch, nitrogen fertilizer, and clipping frequency was studied on herbage and seed production of annual ryegrass (Lolium multiflorum Lam.) seeded on a burned brushland in California. The experiment was continued for 2 years but, in the second year, actual grazing by meadow mice (Microtus californicus) was substituted for the clipping treatment. Available nitrogen in the soil was found deficient in both years but the deficiency was more pronounced in the relatively dry year. Meadow mice reduced herbage and seed yields significantly in the second year. It is concluded that the decline of annual ryegrass in burned brushlands is associated with a corresponding decline through immobilization of available soil nitrogen released by brush burning.