Seasonal herbage production from two range types in southern Mozambique

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Estimating ideal stocking rates in southern Mozambique based on range productivity is difficult since forage and foggage production of range types receiving different amounts of rainfall have not been quantified to date. Exclosures were constructed in upland and alluvial range types in southern Mozambique and forage yields were measured over 6 years on sub-plots harvested when grasses reached 25% flower, in May or in October. Herbage yields were highly correlated (>0.90) to seasonal rainfall that varied from 498 to 837mm yr−1. Upland range produced an average 2.6Mg herbage DMha−1 yr−1 while alluvial soils averaged 6.4MgDMha−1 yr−1. The 25% flower subplots out-yielded (P>0.05) the other harvests only in the first season while the May harvests had greater herbage production (P<0.05) in all other seasons except the high rainfall year. Herbage phosphorus concentration was 13% greater in the alluvial range sites while acid detergent fibre and lignin concentrations were 21.7% and 47.9% higher, respectively, in the May harvests compared to the 25% flower treatments. Average nitrogen values were 35% lower in the May harvests than in the 25% flower harvests but did not decrease further in the October foggage. Harvest regime did not affect (P>0.10) the principal species' relative contribution to herbage from season one to season six. Urochloa mosambicensis decreased in the upland range over the trial, perhaps as a result of successive poor-rainfall seasons.