In the early seventies, scientists in Israel and The Netherlands started a cooperative project on actual and potential production under semi-arid conditions. In Israel research concentrated on primary production of natural pastures and small grain crops, and on the associated secondary production of small ruminants. Most of the experimental work was carried out at the Migda Experimental Farm in the semi-desert of the northern Negev where the long­ term average annual rainfall is 250 mm. In The Netherlands existing facilities in Wageningen were used for measuring growth, photosynthesis and transpiration of Negev pasture plants and small grains under controlled conditions, both as individual plants and as simulated swards and crops. The joint research program was initiated by the late N.H. Tadmor and A. Dovrat from Israel and by C.T. de Wit and Th. Alberda from The Netherlands and conducted by various scientists from both countries, some of whom are among the authors of this book. The experimental results first served as a basis for the development, calibration and validation of simulation models of the growth and water use of pasture and crops. Subsequently, additional models were developed, allowing incorporation of socio-economic considerations, both at the farm and regional level, so harnessing the research results for analysis of regional development possibilities.

1. Introduction.- 1.1. In the current of change.- 1.2. The natural environment.- 1.3 Agro-pastoral systems.- 1.4. Perspectives for development.- 2. Structure and dynamics of grazing systems on seasonal pastures.- 2.1. Introduction.- 2.2. Within-season plant biomass dynamics under grazing.- 2.3. Between-season plant population dynamics and the effects of grazing.- 2.4. Conclusions.- 3. Moisture, nutrient availability and plant production in the semiarid region.- 3.1. Introduction.- 3.2. The water balance.- 3.3. The soil nitrogen balance.- 3.4. Plant production limited by weather, mainly water availability.- 3.5. Plant production limited by weather and nitrogen availability.- 3.6. Grain production in a semi-arid environment.- 3.7. Conclusions.- 4. Sheep husbandry for lamb production in a semi-arid mediterranean environment.- 4.1. The grazing environment.- 4.2. Breeds of sheep in Israel.- 4.3. Reproduction and breeding practice.- 4.4. Ewe nutrition.- 4.5. Lamb production.- 4.6. Flock management.- 4.7. Pasture productivity and systems of utilization.- 5. Description of a pasture system generator (PSG).- 5.1. General outline.- 5.2. Calculation of system inputs and outputs.- 5.3. Cropping systems.- 5.4. PSG activity table.- 5.5. Input and output values calculated by the PSG.- 6. Management of agro-pastoral systems at the farm level.- 6.1. Introduction.- 6.2. Short-term decisions.- 6.3. The agro-pastoral system model.- 6.4. Results of the agro-pastoral system model.- 6.5. Economic efficiency and technical efficiency.- 7. Modelling agricultural development strategy.- 7.1. Introduction.- 7.2. The multiperiod regional development model.- 7.3. Interactive multiple-goal planning.- 7.4. An example of the application.- 7.5. Discussion.- 7.6. Conclusions.- Model activities and constraints by categories.- 8. Summary.- 8.1. Introduction.- 8.2. Primary production.- 8.3. Secondary production.- 8.4. The matrix of production techniques.- 8.5. Management under uncertainty.- 8.6. Regional development.- References.