Over a period of seven years farmers participated in trials in which common vetch (Vicia sativa (V)) or chickling (Lathyrus sativus (C)) replaced the fallow in a barley (Hordeum vulgare)±fallow rotation (F) or were introduced into continuous barley cropping (B) ± giving a total of four rotations, B±F, B±B, B±V and B±C. Trials on 4 ha, 2 ha per phase of each rotation, were replicated on 6±8 farms. Some vetch and chickling crops were grazed in spring. Mean seven-year dry matter yields were 2.91 t ha 71 for B±F, 4.82 t for B±B, 5.02 t for B±C and 5.32 t for B±V; total crude protein outputs were twice as high from rotations including legumes; and the B±V rotation yielded most metabolizable energy. Realizing the bene®t, farmers started to adopt vetch. In 1991 three farmers were growing vetch on 7 ha but by 1997 174 farmers in 15 villages were growing vetch on 420 ha. Forage legumes will not, however, become more widely grown until inexpensive and ecient mechanized methods of harvesting the mature crop are available in order to avoid the high cost of hand labour. Drought and cold tolerance, early maturation and high harvest index may also enhance farmers' interest in forage legumes.
Growing populations and intensification of land-use in West Asia and North Africa (WANA) are prompting a need for viable alternatives to fallow and cereal mono-cropping systems common in dry areas of this region. The sustainability and economic viability of such rotations can only be assessed accurately by using long-term trials. A two-course rotation experiment was established in 1986 in north-eastern Syria, comparing yields and profitability of wheat (Triticum aestivum L.) when grown after wheat, fallow, a grazed mixture of medic species (Medicago spp.) and common vetch (Vicia sativa L.) cut for hay, over 10 growing seasons. Lentils (Lens culinaris Medik.) were introduced into the experiment in 1990. On average over the course of the experiment, the highest wheat grain yields were obtained following fallow (2.57 t ha–1), the lowest in continuous wheat (1.14 t ha–1), and intermediate following medic and vetch (1.90–2.01 t ha–1). Compared with wheat grown after fallow, wheat grain yields declined following vetch, medic and lentils in only three of the 10 seasons, which were drier than average. Yields of wheat after lentils were generally lower (2.22 t ha–1) than after vetch (mean 2.56 t ha–1) and after medic (2.40 t ha–1). Inclusion of grain legumes in the rotations boosted profits considerably because of their high grain prices and valuable straw. Replacing fallow with vetch for hay production increased the average gross margin by US$126 ha–1 year–1, and growing vetch for hay in rotation with wheat produced greater profit than continuous wheat, by $254 ha–1 year–1. The wheat–vetch-for-grain and wheat–lentil rotations were especially profitable, at least twice as profitable as wheat–fallow and three times continuous wheat. This experiment adds to the growing body of field data in Syria and in Australia showing that forage and grain legumes are excellent alternatives to wheat–fallow rotation and continuous wheat production in areas that experience a Mediterranean-type climate, and help support more efficient and sustainable cropping systems.
S U M M A R YThree rates of phosphate (0, 25 and 60 kg/ha P 2 O 5 ) were applied for 7 years to phosphate-deficient grassland at Tel Hadya, north Syria. Liveweight, milk yield, wool production and supplementary feeding of Awassi sheep were monitored for six seasons (1985/86 to 1990/91). The experiment was grazed at low (0-8 sheep/ha per year) and high (1-7 sheep/ha per year) stocking rates from the second to the fourth season, while in the fifth to seventh seasons stocking rates were increased to 11 and 2-3 sheep/ha per year, respectively. The experimental site was typical of communally owned, degraded grasslands within the cereal zone of west Asia, where cropping is not possible because of shallow, stony soils and steep slopes.The results showed that annual applications of phosphate, even at 25 kg/ha, improved pasture and sheep productivity. Liveweights were higher on fertilized plots in five out of six years, significantly so in the last three. Milk production was also higher on phosphate-treated plots, and the need for supplementary feeding was reduced, especially in the last three years, when rainfall was below average. The results suggest that stocking rates can be significantly increased by annual applications of small amounts of superphospate, and that doing so is profitable.Use of the results depends on the presence of native legumes, the level of soil phosphate, and the ability of farmers to control grazing of these communally owned grasslands. A strategy to fulfil these criteria is suggested.
Ninety Awassi ewes managed at different levels were used to study the effect of live weight mating on fertility over 3 years in semi-arid north-west Syria. During the 56-day pre-mating period fertile ewes had higher daily live-weight gains than infertile ewes (P < 0·01), frequency of oestrous cycles increased as live weight increased (P < 0·001) and fertile ewes tended to have more frequent oestruses than infertile ewes (P > 0·05). Ewe fertility was related (r = 0·87) to live weight at mating and twinning reached a maximum (four per 100 ewes lambing) in 51· to 56-kg ewes then decreased fP > 0·05). Maximum fertility can be expected in Awassi ewes weighing over 48 kg at mating in north-west Syria.
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