Impact of livestock grazing systems on pasture production and species diversity in Kasolwe stock farm, Kamuli district

Abstract

Herbage production in grazing systems is regulated by environmental variables, pasture species diversity and characteristics of the sward or pasture. However, changes in biomass production and species diversity of pastures due to change in grazing systems remains unknown among farmers. This study therefore assessed the impact of rotation and continuous grazing systems on pasture biomass yield and species diversity in Kasolwe Stock Farm. A modified-Whittaker plot method was used in collecting the data. Pasture samples were harvested by cutting at ground level, all the pasture in each 0.5 X 2 meter plots to determine pasture species diversity and abundance. The harvested herbage was then dried and weighed to determine the biomass yield for each grazing system. Biomass yield of pastures under paddock grazing system was significantly (P<0.001) higher than that of continuously grazed pastures. Species diversity was significantly different (t= -1.0450) with continuously grazed valleys and gentle slopes exhibited high species richness and evenness, which was within the acceptable ranges of 1.9 – 3.5 for ecologically balanced ecosystems (Krebs, 1989) compared to continuously grazed hill tops and rotationally grazed paddocks. Continuously grazed pastures on the hill and gentle slope had more similar species with the highest Jaccard’s index of 0.4 while the lowest Jaccard’s index of 0.19 was registered for paddocked and valley pastures. The study therefore demonstrated that species diversity, richness and evenness was lower for rotational grazing system and compared to continuously grazed pastures yet rotational grazing system produced more biomass yield. The study recommended that increased efforts be invested in managing forage species diversity to take advantage of landscape variability and climate so as to enhance the multi-functionality, productivity and sustainability of pastures.