Economic significance of dry-land farming in the arid northern Negev of Israel

Abstract

Under arid conditions rainfall-wheat yield relationships analysed by means of simple and multiple regressions principal components and Fisher's orthogonal polynomial method all gave good results. Fisher's technique was then employed to estimate the effect on final yield of a unit change in rainfall. The response curve obtained was used to calculate wheat yields for a cross-section of the northern Negev, where mean annual rainfall varies from 200–411 mm. A 20% profit margin can probably be obtained in seven of every ten years only in an area where the mean annual rainfall is at least 300 mm. Where rainfall is below 300 mm additional irrigation is essential, for in an area of 240 mm 20% profit margins can only be obtained 3–4 times in every 10 years. Under local climatic and soil conditions and agrotechnical practices the highest average yield response to irrigation is obtained during the first 40 days after planting.