Introduction and management of vetch/barley forage mixtures in the rainfedareas of Pakistan - 2. Forage quality

The erects of a range of harvesting times and vetch/barley mixture ratios o n forage quality were investigated in Mediterranean-type environments at th e National Agricultural Research Centre (NARC), Islamabad, which has an ann ual rainfall of around 1000 mm, and at a much drier site at the Arid Zone R esearch Centre (AZRC) at Quetta in Pakistan, during 1994-97. Common vetch ( V), barley (B), and their mixtures at seed ratios of V75B25, V50B50, and V2 5B75 were sown, and 3 harvest time treatments (pre-flowering, full flowerin g, and maturity) were imposed. At NARC, there were significant differences (P < 0.01) in crude protein content, digestible dry matter (DDM), and metab olisable energy (ME) between crop mixture ratios and between different harv est times. Crude protein content in mixtures declined substantially as vetc h in the mixtures was replaced with barley. The treatment V75B25 had the hi ghest crude protein content (>1 t/ha), pure barley was least productive (<3 00 kg/ha), with pure vetch being intermediate in protein yield (700-800 kg/ ha). All 3 mixtures of vetch and barley had higher DDM (4-5 t/ha) and ME va lues of 5-6.5 x 10(4) MJ/ha (highest for treatment V75B25) compared with bo th of the sole crops. DDM and ME in mixtures declined as the proportion of barley in the seed ratio in the mixtures increased, but pure barley had sti ll somewhat more DDM (3.6 t/ha) and ME (43344 MJ/ha) than pure vetch (3.2 t DDM/ha and 42035 MJ ME/ha). At AZRC, the same trends as at NARC were obser ved but with lower yields because of the substantially lower and less well distributed rainfall and suboptimal temperatures.