Yield and Nutritive Values of Grasses in Degraded Communal Savannas of Swaziland Surrounding Dip-tanks and Relationship with Soil and Herbaceous Structure

The use of dip–tanks to control ticks on Swaziland’s communal grazing lands represents an alteration of the natural state of savannas and may have long-lasting effects on the ecology of the surrounding areas. Few studies have explored the zone around dip–tank for gradients of animal impact on soil, forage biomass and nutritive value. Soil and plant samples were collected at 50, 100, 150, 300, 500, 700 and 900 m from dip–tanks in three soil types; deep pale brown old alluvium sandy (DPBS), deep yellow–red loamy (DYRL), and rock outcrops and stony ground (ROSG). All soil minerals except N showed differences among the soil types. Grass biomass was low (range: 126.7–240 kg ha^-1) and together with CP, ADF and NDF, did not show a gradient with distance from a dip–tank. Higher plant Ca, Mg, and P were evident closer to a dip–tank. The relationship between soil and forage mineral was not significant in most instances. The current study has concluded that animals may suffer from low nutrient intake during the growing season and therefore should be supplemented. Since grass production was low, a holistic communal based rangeland management programm and fodder flow interventions are needed to restore the productivity.