The effect of depth of seeding, moisture stress, shading and mulching on the emergency of a number of sub?tropical pasture legumes was examined on two contrasting soil types in the greenhouse. The legume species used were Desmodium intortum, D. uncinatum, Glycine wightii, Macroptilium atropurpureum, Stylosanthes guianensis and Trifolium semipilosum. Two contrasting soils were used, a granite?derived sand and a silt?rich soil which forms a crust. Surface seeding was unsatisfactory on both soil types and the highest rate of emergence of all species was obtained with sowing depths of 5 or 10 mm. However, several of the legumes, including some with relatively small seeds, were tolerant of deeper sowing on the sandy soil. Differential moisture stress was induced by varying the amount and frequency of water application. These treatments were applied in combination with various shading and mulching treatments. Under conditions of moisture stress both shading and mulching incrsased seedling emergence. On the silt?rich soil where moisture was adequate, shade was beneficial but mulching was harmful. On the silty soil, seedling emergence was correlated with the strength of the crust. Crust strength was found to vary with time as the soil dried out, increasing initially but subsequently decreasing. Certain discontinuities in the pattern of water loss during drying were found in the silt?rich soil. These seem to be associated with cracking of the soil surface. This aspect warrants further investigation as does the apparently harmful effect of the mulch under conditions of adequate moisture.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.