LEAF QUALITY OF SESBANIA-SESBAN, LEUCAENA-LEUCOCEPHALA AND BRACHYSTEGIA-SPICIFORMIS - POTENTIAL AGROFORESTRY SPECIES

A total of 75 trees were sampled for leaf nutrient content in January 1990, 15 each from Leucaena leucocephala var. cunningham and Sesbania sesban, and 45 from three age classes of Brachystegia spiciformis. For every three trees sampled per species or age class, the samples were thoroughly mixed and a composite sample was drawn which was oven-dried, ground and analysed for dry matter digestibility, acid detergent fibre, lignin, nitrogen, phosphorus, potassium, calcium and magnesium content. The highest leaf quality was recorded in S. sesban, this having significantly higher levels than L. leucocephala of phosphorus, calcium and in vitro dry matter digestibility, and a lower value for fibre. L. leucocephala was better than S. sesban only for nitrogen content of leaves. The lowest quality litter was recorded in B. spiciformis with generally lower levels of all nutrients, crude protein, in vitro dry matter digestibility, and highest levels of fibre and lipin. There were no consistent differences among the different age classes of B. spiciformis, with only a slight tendency for higher nitrogen and crude protein levels in coppice growth. To improve soil fertility on already cleared land, one option is to introduce S. sesban and L. leucocephala litter.