The effect of clipping on growth and nutrient uptake of Sahelian annual rangelands

Abstract

1. growth and nutrient-uptake responses of annual rangeland to defoliation were studied at 13 sandy range sites located across the Sahelian zone of mali between 1977 and 1989. 34 clipping experiments (site-years) were conducted using identical treatment designs with respect to the timing and frequency of clipping. 2. the effect of highly variable growing conditions (rainfall and nutrient availability) on the response to clipping was analysed through a series of regression analyses. 3. The growth response of vegetation to clipping is more related to variables associated with rainfall and growing condition than to clipping frequency. Total yields were lowered most during periods of rapid growth. 4. Nitrogen (N) and phosphorus (P) yields were not affected by growing condition while clipping consistently increased N and P yield. 5. Greater sink strength in clipped plants better explains the observed stimulation of modified soil water status after clipping. 6. The significance of these results for the ecological management of Sahelian rangelands is discussed.