Whole - farm model based on experimental flocks and crop rotations in northwest Syria

Four rainfed crop rotations - (1) barley-fallow, (2) barley-vetch, (3) wheat-lentil-watermelon, and (4) wheat-vetch-watermelon - were tested over a 6-year period to compare traditional rotations (1 and 3) with high input rotations (2 and 4) which incorporated vetch crops for pasture or hay. Experimental flocks of Awassi ewes provided nutrition-performance data; preliminary estimates were used for native pasture offtakes, with and without phosphate fertilizer; and a 1985 farm survey provided price data. The data were integrated using linear programming, and optimal solutions were computed for 36 resource and management scenarios. The high input rotations yielded greater profits under all comparable resource conditions and were associated with greater crop yields and sheep numbers. Profits and ewe numbers increased when native pasture was added to the farm, and increased further with fertilized pasture. Optimal ewe numbers declined with a change from low to high nutritional regimes, but farm profits were little affected. The analysis suggests that the replacement of fallow and lentils by vetch may, with judicious management, lead to more productive and profitable crop-livestock husbandry in similar environments. The programming model used by ICARDA is described in sufficient detail to enable others to repeat or modify the experiment. (Author abstract, modified)