Evaluation of forage potential and utilization of a rangeland area west of the Ruvu floodplains, Bagamoyo district, Eastern Tanzania.

A study was conducted to determine the floristic composition, abundance, species diversity and nutritive value of the herbaceous species; and the soil fertility status of the rangeland area west of the Ruvu floodplains. A total of 100 plant species from 30 families were recorded within four study sites. The majority were grasses, followed by dicotyledonous herbs, sedges and a few immature woody shrub species. The family, Gramineae (Poaceae) had the highest species diversity with 23 perennials and 2 annuals. Only Sporobolus panicoides .A.Rich was of no grazing value. But the rest had varying grazing value and palatability at one or all growth stages. Species diversity values for the herbaceous layer ranged between 1.18 to 1.40 in the sites, with no significant differences (p>0.05). There were significant differences (p<0.05) in the floristic composition of the sites which were attributed to variations in range management practices. Perennial and palatable grass species were abundant indicating good range condition. The dominant perennial grasses were Panicum maximum Jacq., Panicum parvifolium Lam., Sporobolus pyramidalis P. Beauv., and Urochloa mosambicensis (Hack.) Dandy. Some grasses attained heights of 11/2m in many areas indicating that this rangeland is underutilized. The grass and browse species had adequate crude protein, crude fibre, phosphorus, calcium, and magnesium to support livestock growth and maintenance. They were, however, significantly different in their crude protein, crude fibre and mineral contents, with browse having higher nutritive value. Range management practices on the different study sites had no influence on the nutritive value of the grass species. Composite grass samples among the sites were not significantly different in their %CP, %CF, Ca, Mg, and P contents. Only calcium was strongly influenced by the soil's elemental content, while Mg and P were not. Soil texture was mostly loamy sand, with sandy clay found in some areas. The soils exhibited significant differences between sites in their pH, K, Na and total exchangeable bases. The sites were not significantly different in organic matter, available P, Ca, and Mg contents though variations were observed in the P, and Ca values within the sites. The implications of these results for rangeland utilization particularly for livestock production, and management are here discussed.