The cage method of sampling to assess herbage mass and herbage consumed on annual rangeland vegetation

Abstract

The cage method of sampling vegetation was used to estimate herbage mass and herbage consumed by sheep, grazing a pasture dominated by annual species, near Camawon, Western Australia. Using paired quadrats (2m x lm), one caged and the other open, herbage mass and herbage consumed were measured at five stocking rates on two soil types, on eight occasions between December 1983 and January 1985. The data were highly variable; nevertheless, some effects of season, soil type and stocking rate could be observed. The results showed clear seasonal trends. Some soil type x stocking rate interactions were detected during the dry periods of the year when herbage mass was low. Generally, the cage method tended to over-estimate herbage consuped. Sheep consumed approximately 119 to 116 of the available herbage at low and high stocking rates respectively when feed was plentiful; when feed was in short supply the corresponding figures were approximately 113 and 1/2. The limitations of the method are discussed and some suggestions made concerning its applicability in rangeland studies.