ASSESSMENT OF GRAZING LAND CONDITION, HERBACEOUS BIOMASS SPECIES AND CHEMICAL COMPOSITION IN ADAMI-TULLU JIDO-KOMBOLCHA AND ARSI NEGELLE WOREDAS, SOUTHERN ETHIOPIA

Abstract

This study was conducted in Adami-Tullu Jido-Kombolcha and Arsi Negelle woredas, Southern Ethiopia. The objectives of the study were: (1) To assess the effects of grazing pressure and altitude on range condition, herbaceous biomass and species composition in the study areas and (2) To evaluate the effects of grazing pressure and altitude on chemical composition of herbaceous plants in the study areas. In the assessment of rangeland condition: grass species composition, basal cover, litter cover, number of seedlings, age distribution of dominant grasses, soil erosion and compaction were considered. The data were analyzed using GLM procedure in SPSS 16.0 version, which was used for mean comparisons using post-hoc t-test that can be employed to compare mean differences for enclosure and open grazed areas. To test the effect of management and altitude on rangeland condition, biomass production, chemical composition of herbaceous species, mixed model analysis was used where site was used as a random variable while management and altitude were fixed variables. The rangeland condition assessment factors showed that grass species composition, basal cover, litter cover, age distribution, number of seedlings, soil erosion and compaction, and total range condition scores in the enclosed areas were significantly (p<0.05) higher than in the open grazed areas. A total of 28 herbaceous species were identified. Of the identified herbaceous species, 20 were grasses, 2 were legumes while 6 species were forbs. Among the recorded grass species, some were highly desirable, while others were in the category of intermediate in terms of desirability and less desirable. The total biomass production of grasses, forbs and legumes in the enclosure areas were significantly (p<0.05) higher than that of the open-grazed areas across the study sites. The dominant and common grass species included: Arstida adscensionis, Cenchrus ciliarus, Chloris gayana, Chloris roxburghiana, Bothriochloa insculpta, Entropogon, Eragrostis papposa, Heteropogon contorus, Panicum maximum, Bides pilos sida ovate,Indigofer spinosa, Tephrosia pumila, Sporobolus pyrmidalis, Themeda triandra, B. nigropedata, Ocimum basilicum, Amaranthus dubis, Tribulos terrestris and Achyrantes aspera. The chemical composition of herbaceous plants were evaluated for DM, CP, NDF, ADF, ADL and Ash between the two management systems and among three site of different altitude for grazing land condition. The average CP content in the open-grazed area was significantly (p<0.05) higher than that of enclosure grazing areas. This suggests that proper management of grazing lands in the study areas is required as part of the grassland monitoring activities and restoration programs. It is also suggested that the herbaceous forages were utilized at early stage of maturity to provide optimum nutrients for animals in the study area