lmprovement of the subhumid Mediterranean natural dryland pasture through fertilization and time of grazing

Julia Avendaño R.1, Carlos Ovalle M.2

The effects of fertiliza-tion and time of grazing on dry matter yield, botanical composition and pastoral value (VP.) of a natural pasturewere evaluated during seven years.
Annual fertilization during seven years, produced significant increases on dry matter yield (annual means for seven years were 3,365 and 1 ,553 kg/ha for the annually fertilized and the non fertilized range, respectively). Besides, a modification of the botanical composition, towards the dominance of Lolium multiflorum and appearing legumes (Medicago híspida, principally) was observed, the pasture attaining a V.P. of about 46 units versus 16 units of the non fertilized, means of the last three years.
When fertilized only for the first four years, the range yielded as much as with continual annual fertilization and more than when not fertilized at all, only up to the year following the last fertilization (fifth year); also, the VP. (45.2 u) was similar to the one with continual annual fertilization (56.2) and higher to the one not fertilized (29.5 u), up to three years after the last application.
Time of grazing had a tendency to modify only the botanical composition. The higher VP. wereattained when the range was grazed after flowering and on the non grazed (defered). The range grazed before flowering presented the lowest VP.

1 Subestación Experimental Cauquenes (INIA), Casilla 165, Cauquenes, Chile.
2 Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.