Five Euphorbiaceae species (Jatropha macrocarpa, J. hieronymi, J. excisa, Cnidoscolus tubulosus and Manihot guaranitica) were analysed for seed oil content and fatty acid profiles in order to evaluate their potential as sources of biodiesel. The five species are perennial shrubs adapted to arid and semi-arid environments of north-western Argentina. The seed oil content for all species ranged from 27.9 to 38.7% by dry weight. Fatty acid composition consisted mainly of linolenic, myristic, palmitic, stearic, arachidic, oleic and linoleic acids, with linoleic and oleic acid being the most abundant. Among the five species analysed, J. macrocarpa has the best potential to be used as a biodiesel source. The average total seed oil content (35.8%) and a high value of oleic acid (27.3%) together with the lowest values of linoleic acid (55.8%) make this species a promising crop as a source of biodiesel in arid and semi-arid regions.

Turkey is experiencing pressure to increase crop production per unit area to achieve self-reliance in food supply. The main production concern before 1970 was to increase crop yields to meet the national consumption of an ever-increasing population. During this time the country's capability to produce wheat was insufficient to meet the national demand. After the initiation of the National Wheat Research and Extension Project in 1969 the objectives of wheat production methods were changed to achieve not only higher but more economical yields per unit area. As a result the total area sown to wheat increased by only 9% between 1969 and 1990, whereas yields and total production increased 75 and 90%, respectively. This was due to developing or importing high-yielding varieties adapted to dry areas, increasing use of fertilizers and plant protection chemicals, and timely use of proper tillage made possible with modem equipment. Transferring research results to farmers and exchanging information with international scientists led Turkish scientists to establish the new goal of developing ecologically sound farming systems that could achieve higher, more economical yields per unit area. The key to this approach is to maintain or increase soil organic matter.

Agriculture in Israel is practiced throughout the country from the Arava Valley in the South, where average annual rainfall is less than 40 mm, to the Upper Galilee in the North, where annual rainfall exceeds 700 mm. Less than half the cultivated area used for field crops is irrigated. Much of the output is exponed, primarily to Europe, but some to the United States and Japan. In nonirrigated dry-farming areas, the main crops grown are wheat for grain and silage and several secondary crops, including sunflower, watermelons and hay legumes. Animal production is predominantly intensive dairying (mainly cows, but also sheep and goats), poultry production, and aquaculture, all of which use large quantities of imported feed grains. Beef production is largely from dairy bullocks, but includes an important rangeland beef sector. Problems that face Israeli agriculture in general and dryland agriculture in particular are primarily economic, including low prices for many traditional dryland crops, a small local market, and increasing input costs. The changing socioeconomic scene, reflected by decreasing employment in agriculture, has added to the problems of proper land use. There is an urgent need for more appropriate production systems and associated innovative research and development. This includes management for higher output/input ratios, conservation and enhancement of genetic resources, crop diversification, integration of crop and livestock production, and alternative land use options such as agroforestry, recreation, ecological refuges, and landscape enhancement. These challenges are common to most countries in the Middle East, and offer opportunities for regional and international collaboration to improve the sustainability of agriculture in the region.

An evaluation of agricultural systems often involves multidisciplinary teams that include crop scientists, animal scientists, soil scientists, pest control specialists, agricultural economists, and others. Agricultural economists can improve the technical quality and comprehe nsiveness of agricultural systems research in six major areas: budgeting and investment analyses; whole-farm and institutional factors; risk considerations; aggregate effects on crop and livestock prices; society-wide welfare effects of technical or policy changes; and economic values of environmental and other nonmarket effects. Economic analysis has been part of several successful multidisciplinary research efforts in the United States Pacific Northwest. These have covered soil conservation, integrated pest management, sustainable agriculture, crop rotation choice, and beef ranch management. As an example of institutional influences on economic outcomes, one study showed that the structure and selectivity of United States commodity programs have favored conventional over low-input rotations. Regarding risk management, an appropriate “package system” including conservation tillage, a diversified crop rotation, and adequate chemical weed management was shown both to sustain profitability and to reduce income fluctuations. Properly designed economic analysis can make similar contributions to identifying successful dryl and agricultural technologies throughout the world.

Sustainable rainfed cropping systems are needed in the Pacific Northwest of the United States to reduce or eliminate wind and water erosion, improve soil quality, and control weeds with reduced chemical inputs. A grass seed cropping system is excellent for improving soil quality and for controlling erosion, and can be grazed by sheep to produce meat and wool Tilla ge and residue management methods that create a rough surface to reduce wind and water erosion and increase water infiltration include: use of a chisel to create large clods; leaving residue on the surface; and use of the Paratill to shatter the soil to increase water infiltration with little disturbance of the soil surface. Including a legume in the rotation may help to break disease cycles, add N and C to the soil, and improve soil biological properties. The use of surface residues and tillage to control erosion and increase water infiltration may demand new approaches to weed contro I Rhizobacteria that attack the roots of weeds but not of wheat may reduce the need for chemica I herbicides. Research being conducted on these techniques in the Pacific Northwest of the United States and in other countries should soon result in guidelines for sustainable agricultural systems for the dryland, rainfed areas of the world.