Screening of legumes for veld reinforcement.

Abstract

In order to test their suitability for veld reinforcement, Desmodium intortum, D. sandwicense, D. uncinatum, Glycine wightii, Listia heterophylla, Lotononis bainesii, Macroptilium atropurpureum, Stylosanthes fruticosa, S. humilis and three strains of S. guianensis were seeded in December 1970 in disced veld at Marandellas (sand) and near Mazoe (clay). Starting in December 1971 the legumes were grazed in common at two stocking intensities during the wet season only, the dry season only or year-round, using a simulated rotational grazing system. Legume seedling mortality was high on the sand and only M. atropurpureum and the five Stylosanthes lines had plant densities in the second season greater than 1 plant/m 2. On the clay establishment was better and all legumes except L. heterophylla had densities greater than 1 plant/m 2. Oxley fine-stem stylo was the only legume to persist and spread on the sand but on the clay a much wider range of legumes persisted, although all were adversely affected by a hot fire in July 1976. D. uncinatum, L. heterophylla and L. bainesii were the most persistent legumes on the clay and spread widely. Grazing treatment did not greatly affect the persistence or spread of the legumes. However, at both sites the frequency of the undesirable grass Sporobolus pyramidalis increased in the plots grazed during the wet season. On the clay this was associated with a reduction in the frequency of Hyparrhenia spp. The possible shortcomings and the applicability of this type of trial are discussed.

Keywords: botany; clay; desmodium intortum; desmodium sandwicense; desmodium uncinatum; establishment; fire; glycine wightii; grass; grasses; grazing; legumes; listia heterophylla; lotononis bainesii; macroptilium atropurpureum; marandellas; mazoe; mortality; persistence; plant density; rotational grazing; sand; season; sporobolus pyramidalis; stylosanthes fruticosa; stylosanthes guianensis; stylosanthes humilis; veld reinforcement; zimbabwe