Grass species composition, distribution, biomass production potential and nutritional value in three selected Communal Rangeland Areas under Msukaligwa Local Municipality, Mpumalanga province

Abstract

Veld condition is dependent on abiotic and biotic factors such as vegetation dynamics, climatic conditions and soil characteristics. Therefore, this study assessed the spatial variation of grass species composition, distribution, biomass production potential and nutritive value from selected communal rangelands in Msukaligwa municipality, South Africa. The communal rangelands covered three different soil types (Breyten= Hutton), (Davel= Avalon), and (Wesselton= Clovelly). Grass composition and distribution were assessed using a 100 m permanent line point method, replicated three times at 50 m intervals. Grass species were recorded at 1 m marked point intervals within a 10 cm radius. Life form, palatability, ecological status and abundance data were recorded for all grass species found in each site. Hutton soil had high (P<0.05) concentrations (mg/kg) of N-NO3, N-NHO4, C, P, Cu, and Al compared to the same minerals recorded from Avalon and Clovelly soil types which had similar (P<0.05) concentration values. Hutton soil type also had the highest (P<0.05) percentage of palatable grass species (9.6%) and the lowest (P<0.05) percentage of unpalatable grass species (3.50%) compared to the Avalon and Clovelly soil types which had a lower (P>0.05) percentage of palatable and the highest (P<0.05) unpalatable grass species. No significant difference (P>0.05) was observed in biomass (kg/ha) yield across the three soil types. A variety of 31 grass species were found in all the three soil types, but only 6 were classified as common and dominant and were (Aristida congesta, Digitaria eriantha, Eragrostis chloromelas, Eragrostis curvula, Eragrostis plana, and Eragrostis gummiflua). These species were distributed across all soil types and were thus considered for nutritional characterization. Digitaria eriantha, E. plana and E. gummiflua in Hutton soil type had the highest (P<0.05) N values (17.0, 12.8 and 10.5 g/kg DM, respectively) when compared to the same species in other soil types. Eragrostis chloromelas in Avalon soil type had the

highest (P<0.05) ADL concentration (189.3 g/kg DM) when compared to the same species in other soil types, which did not differ (P>0.05) significantly from each other. Digitaria eriantha on Hutton and Clovelly soil types had higher (P<0.05) Ca concentration (4.1 and 4.3 g/kg DM, respectively) when compared to all other species. Eragrostis chloromelas on Hutton and Clovelly soil types had higher (P<0.05) Fe concentration (259.2 and 186.3 g/kg DM, respectively) when compared to the same species on the Avalon soil type. With regards to in vitro ruminal fermentation, E. chloromelas on Clovelly soil had the highest (P<0.05) 36 h dry matter degradability (DMD) (649.3 g/kg DM) when compared to the same species on other soil types. Overall, the results showed that soil type did not affect the biomass yield. Although all communal study areas were not degraded, soil nutrient status such as C and N was lower on Avalon and Clovelly soil types. The results also indicate that soil type affected the chemical composition of grass. Nitrogen supplementation will be required for all soil types. This study provides farmers, researchers and agricultural advisors with information on grazing grass standards, rangeland conditions, species composition and, feeding value.