Cattle Productivity and Nutrient Fluxes on an Amazon Pasture

Abstract

Cattle grazing, defecation and urination rates, growth, and mortality were studied on pasture formed from rain forest in the Amazon territory of Venezuela. Cattle consumed 12-16 percent of total aboveground plant productivity on two pasture sites. The nutrients in this vegetation were recycled to the soil in dung (N, P, Ca, and Mg) and in urine (N and K). Nutrients recycled in cattle excreta were more available to plants and more spatially concentrated than nutrients in litterfall. The stocking rates on two pasture sites were 0.43-0.89 animal units/ha, and cattle productivity ranged from 21 to 42 kg live wt/ha/yr. Nonharvested mortality was 20 percent per year, and there was no successful reproduction. The low growth rates, reproductive failure, and part of the mortality may result from low phosphorus concentration in the grass.