Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-22T00:31:50.413Z Has data issue: false hasContentIssue false
  • English
  • Français

Improving Water use Efficiency of Annual Crops in the Rainfed Farming Systems of West Asia and North Africa

Published online by Cambridge University Press:  03 October 2008

P. J. M. Cooper ,
P. J. Gregory ,
D. Tully  and
H. C. Harris
P. J. M. Cooper
Affiliation:
Farming Systems Programme, ICARDA, PO Box 5466, Aleppo, Syria
P. J. Gregory
Affiliation:
Department of Soil Science, University of Reading, London Road, Reading, RG1 5AQ, England
D. Tully
Affiliation:
Farming Systems Programme, ICARDA, PO Box 5466, Aleppo, Syria
H. C. Harris
Affiliation:
Farming Systems Programme, ICARDA, PO Box 5466, Aleppo, Syria
Rights & Permissions [Opens in a new window]

Summary

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Farming systems in west Asia and north Africa have evolved to cope with the problems of highly variable and, frequently, chronically deficient rainfall. Cereals (mainly wheat and barley) are the dominant arable crops with food legumes (chickpea, lentil and faba bean) occupying only 5 to 10% of the area planted to cereals. Livestock is closely integrated into the farming system and crop production practices often reflect the importance of animals as a major source of income, particularly on the smaller farms. Soils of the region are predominantly calcareous, frequently phosphate deficient, and their depth and texture are important in determining the maximum amount of water that can be stored which, in turn, may determine the effective length of the growing season.

Rain falls mainly during the winter months so that crops must often rely on stored soil moisture when they are growing most rapidly. Analysis of equations relating crop growth and water use shows that there are three ways in which the ‘water use efficiency’ of dry matter production can be increased. First, the amount of dry matter produced per unit of water transpired might be increased; second, if the water supply is limited, the amount of water transpired might be increased relative to evaporation from the soil surface; and third, the total amount of water used might be increased to produce extra growth provided that this results in increased transpiration rather than simply increasing evaporation from the soil surface.

These three possible routes to increased crop growth are reviewed in relation to possible improvements in water management and crop genotypes in the Mediterranean environment. Scope for improving transpiration efficiency is limited although genotypic differences exist and may be useful in the future. More immediately, changes in crop management, such as applications of fertilizer, improved tillage and better weed control, will all increase the amount of water transpired. Application of mulches will also reduce evaporation from the soil surface but crop residues are usually eaten by livestock and are, therefore, often unavailable.

The barley/livestock farming system of west Asia is used as a case study to illustrate how the Fanning Systems Programme of ICARDA has developed on-farm research programmes of direct relevance to current farming systems. Research on experimental sites directed at improving water use efficiency has been developed into on-farm trials and into collaborative trials with the Syrian Soils Directorate.

Type
Research Article
Information
Experimental Agriculture , Volume 23 , Issue 2 , April 1987 , pp. 113 - 158
Copyright
Copyright © Cambridge University Press 1987

References

REFERENCES

Anderson, W. K. (1984). Plant populations for triticale in a Mediterranean environment. Field Crops Research 8:281–95.CrossRefGoogle Scholar
Anderson, W. K. (1985a). Production of green feed and grain from grazed barley in northern Syria. Field Crops Research 10:57–75.CrossRefGoogle Scholar
Anderson, W. K. (1985b). Grain yield responses of barley and durum wheat to split nitrogen applications under rainfed conditions in a Mediterranean environment. Field Crops Research 12:191–202.CrossRefGoogle Scholar
AOAD (Arab Organization for Agricultural Development, League of Arab States) (1984). 1983 Yearbook of Agricultural Statistics, Vol. 3. Khartoum: AOAD.Google Scholar
Aricanli, T. & Somel, K. (1979). Observations on developments in agriculture and land distribution in Turkey. (In Turkish). Studies in Development 6:91–110.Google Scholar
Aschmann, H. (1977). Historical development of agriculture in semi arid regions of winter precipitation. In Proceedings International Symposium on Rainfed Agriculture in Semi Arid Regions, Riverside, California, U.S.A., April 1977.Google Scholar
Bakhtri, N. (1979). Introduction of the medic/wheat rotation in the North African and Near East countries. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, 05 5–10, 1979, 118–125.Google Scholar
Benzaghou, M. M. (1979). Situation des cereales en Algerie. In Proceedings of the Fifth Regional Workshop, Ministry of Agriculture and Agrarian Revolution, Algeria; CIMMYT (Mexico City) and ICARDA (Aleppo, Syria), Algiers, 5–9 05 1979, Vol. 1, 15–21.Google Scholar
Bierhuizen, J. F. & Slatyer, R. O. (1965). Effect of atmospheric concentration of water vapour and CO2 in determining transpiration-photosynthesis relationships of cotton leaves. Agricultural Meteorology 2:259–70.CrossRefGoogle Scholar
Bolton, F. E. (1981). Optimizing the use of water and nitrogen through soil and crop management. Plant and Soil 58:231–248.CrossRefGoogle Scholar
Brichambaut, G. de & Wallen, G. (1963). A study of agroclimatology in the semi-arid and arid zones of the Near East. Technical Note 56. Geneva: WMO.Google Scholar
Bristow, K. L., Campbell, G. S., Papendick, R. I. & Elliott, L. F. (1986). Simulation of heat and moisture transfer through a surface residue-soil system. Agricultural and Forest Meteorology 36:193–214.CrossRefGoogle Scholar
Brouwer, R. (1963). Some physiological aspects of the influence of growth factors in the root medium on growth and dry matter production. Jaarb. Institute Biologic Scheik Onderz Landb Gewass, 1963, 11–30.Google Scholar
Brown, P. L. (1971). Water use and soil water depletion by dryland winter wheat as affected by nitrogen fertilization. Agronomy Journal 63:43–46.CrossRefGoogle Scholar
Brown, S. C., Keatinge, J. D. H., Gregory, P. J. & Cooper, P. J. M. (1987). Effects of fertilizer, variety and location on barley production under rainfed conditions in Northern Syria. 1. Root and shoot growth. Field Crops Research (In press).CrossRefGoogle Scholar
Campbell, R. R., Follet, R. H., Howell, H. B., Riddle, R., Stubbendieck, J. T. & Hamway, D. G. (1977). Applied agronomic research program for dryland farming in 200–400 mm rainfall zone of Morocco. Publication No. PN-AAF-329. Washington, D. C.: USAID.Google Scholar
Caprio, J. M., Grunwald, G. K. & Synder, R. D. (1985). Effect of standing stubble on soil water loss by evaporation. Agricultural and Forest Meteorology 34:129–144.CrossRefGoogle Scholar
Cooper, P. J. M. (1983). Crop management in rainfed agriculture with special reference to water use efficiency. In Proceedings of the 17th Colloquium of the International Potash Institute, Rabat, Morocco, 05 1983, 19–35.Google Scholar
Cooper, P. J. M., Allan, A. Y., Harmsen, K., Keatinge, J. D. H., Nygaard, D., Saxena, M. & Islam, R. (1981). Soil water and nutrient research. 1979–80. ICARDA Project Report No. 3. Aleppo, Syria: ICARDA.Google Scholar
Cooper, P. J. M., Gregory, P. J., Keatinge, J. D. H. & Brown, S. C. (1987). Effects of fertilizer, variety and location on barley production under rainfed conditions in northern Syria. 2. Soil water dynamics and crop water use. Field Crops Research (In press).CrossRefGoogle Scholar
Cooper, P. J. M., Keatinge, J. D. H. & Hughes, G. (1983). Crop evapotranspiration - a technique for calculation of its components by field measurements. Field Crops Research 7:299–312.CrossRefGoogle Scholar
Day, W., Legg, B. J., French, B. K.Johnstone, A. E., Lawlor, D. V. & de Jeffers, W. (1978). A drought experiment using mobile shelters: the effect of drought on barley yield, water use and nutrient uptake. Journal of Agricultural Science, Cambridge 91:599–623.CrossRefGoogle Scholar
Dennett, M. D., Rodgers, J. A. & Keatinge, J. D. H. (1983). Simulation of a rainfall record for the site of a new agricultural development: an example from Northern Syria. Agricultural Meteorology 29:247–58.CrossRefGoogle Scholar
Doren, D. M. van & Allmaras, R. R. (1978). Effect of residue management practices on the soil physical environment, microclimate and growth. In Crop Residue Management Systems, Agronomy Monograph No. 31, 49–83. Madison: American Society of Agronomy.Google Scholar
El-Fauly, M. M. (1983). Micronutrients in arid and semi arid areas: levels in soils and plants and the need for fertilizers with reference to Egypt. In Proceedings of the 17th Colloquium of the International Potash Institute, Rabat, Morocco, 05 1983, 163–174.Google Scholar
FAO (1978). Report on the agro-ecological zones project, Vol. 1. Methodology and results for Africa. World Soils Resources Report 48/1. Rome: FAO.Google Scholar
FAO (1979). Report on the agro-ecological zones project, Vol. 2. Results for South West Asia. World Soils Resources Report, 48/2. Rome: FAO.Google Scholar
FAO (1984). 1983 FAO Production Yearbook, VoL 37. Rome: FAO.Google Scholar
Farquhar, G. D. & Richards, R. A. (1984). Isotopic composition of plant carbon correlates with water-use efficiency of wheat genotypes. Australian Journal of Plant Physiology 11:539–52.Google Scholar
Fischer, R. A. (1981). Optimizing the use of water and nitrogen through the breeding of crops. Plant and Soil 58:249–78.CrossRefGoogle Scholar
Fischer, R. A. & Kohn, G. D. (1966). The relationship of grain yield to vegetative growth and post flowering leaf area in the wheat crop under conditions of limited soil moisture. Australian Joumal of Agricultural Research 17:281–295.CrossRefGoogle Scholar
French, R. J. & Schultz, F. E. (1984). Water use efficiency of wheat in a Mediterranean-type environment. 1. The relation between yield, water use and climate. Australian Journal of Agricultural Research 35:743–64.CrossRefGoogle Scholar
Ghanem, H., Amnai, L., Azzaoui, H., Bouksirat, H., El Gharous, M. & Oubakammou, S. (1983). Nitrogen, phosphate and potassium and management of arid and semi arid soils of Morocco & Preliminary results of a large scale project. In Proceedings of the 17th Colloquium of the International Potash Institute, Rabat, Morocco, 05 1983, 259–278.Google Scholar
Gibbon, D. (1981). Rainfed farming systems in the Mediterranean region. Plant and Soil 58:59–80.CrossRefGoogle Scholar
Goudriaan, J. & van Laar, H. H. (1978). Relations between leaf resistance, CO2-concentration, and CO2-assimilation in maize, beans, lalang grass and sunflower. Photosynthetica 12:241–249.Google Scholar
Gregory, P. J. (1984). Water availability and crop growth in arid regions. Outlook on Agriculture 13:208–215.CrossRefGoogle Scholar
Gregory, P. J., Shepherd, K. D. & Cooper, P. J. M. (1984). Effects of fertilizer on root growth and water use of barley in northern Syria. Journal of Agricultural Science, Cambridge 103:429–38.CrossRefGoogle Scholar
Grigg, D. (1974). Farming Systems of the World. Cambridge: Cambridge University Press.Google Scholar
Guler, M., Unver, I., Pala, M., Duratan, N. & Karaca, M. (1979). The fallow system and cereal production in the dryland areas of Turkey. In Proceedings of the Fifth Regional Workshop, Algiers, 5–9 May 1979. Ministry of Agriculture and Agrarian Revolution, Algeria; CIMMYT (Mexico City) and ICARDA (Aleppo, Syria). Vol 2, 75–86.Google Scholar
Haddad, G. A., Chaudhry, F. M., Haque, I. & Khan, G. A. (1979). Effect of micronutrient fertilization on various legumes and cereals in the Kufra Oasis. In Proceedings of 3rd Symposium of C.I.E.C. on Water and Fertilizer Use for Food Production in Arid and Semi-arid Zones, 303–308 (Ed. Weltze, E.). Gottingen: CIEC.Google Scholar
Harison, H., Borlaug, N. E. & Anderson, R. G. (1982). Wheat in the Third World. Boulder, Colorado: Westview.Google Scholar
Harmsen, K. (1984a). Dryland barley production in Northwest Syria. I. Soil conditions. In Proceedings of Soils Directorate/ICARDA Workshop on Fertilizer Use in Dry Areas, March 1984, Aleppo, Syria, 12–41.Google Scholar
Harmsen, K. (1984b). Dryland barley production in Northwest Syria. II. Chemistry and fixation of phosphorus in calcareous soils. In Proceedings of Soils Directorate/ICARDA Workshop on Fertilizer Use in Dry Areas, March 1984, Aleppo, Syria, 42–67.Google Scholar
Harmsen, K., (1984c). Nitrogen fertilizer use in rainfed agriculture. Fertilizer Research 5:371–382.CrossRefGoogle Scholar
Harmsen, K., Shepherd, K. D. & Allan, A. Y. (1983). Crop response to nitrogen and phosphorus in rain-fed agriculture. In Proceedings of the 1 7th Colloquium of the International Potash Institute, Rabat, Morocco, May 1983, 223–248.Google Scholar
Hepworth, H. M., Zinn, T. G. & Anderson, W. L. (1975). Improved Techniques for Dryland Agriculture Means More Wheat from Fallow Farming. (2nd Edition). Ankara, Turkey: USAID/Oregon State University Team.Google Scholar
Hogan, E. B., Furtick, W. R. & Grayzel, J. A. (1984). Morocco Increase in Cereal Production. Report to USAID, Washington, D. C.Google Scholar
ICARDA (1982). Annual Report, 1981. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
ICARDA (1983). Annual Report 1982. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
ICARDA (1984). Annual Report 1983. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
ICARDA (1985). Annual Report 1984. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
ICARDA (1986). Annual Report 1985. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Ismail, H. N. (1974). Water use efficiency of wheat, linseed and cotton grown in the central region of Iraq. Iraqi Journal of Agricultural Science 9:18–26.Google Scholar
Janssen, B. H. (1972). The significance of the fallow year in the dry-farming system of the Great Konya Basin, Turkey. Netherlands Journal of Agricultural Science 20:247–260.CrossRefGoogle Scholar
Jaubert, R. & Oglah, M. (1985). Farming systems management in the Bueda/Breda sub area 1983/84. ICARDA Research Report. Aleppo, Syria: ICARDA.Google Scholar
Jaubert, R. & Thomson, E. (1985). Sheep feeding strategies at Bueda, N.W. Syria. In ICARDA Annual Report 1984, 29–33. Aleppo, Syria: ICARDA.Google Scholar
Kallsen, C E., Sammis, T. W. & Gregory, E. J. (1984). Nitrogen and yield as related to water use of spring barley. Agronomy Journal 76:59–64.CrossRefGoogle Scholar
Karouzis, G. (1980). Report on Aspects of Land Tenure in Cyprus. (2nd Edition). Nicosia: Ministry of Agriculture and Natural Resources.Google Scholar
Kassam, A. H. (1981). Climate, soil and land resources in North Africa and West Asia. Plant and Soil 58:1–29.CrossRefGoogle Scholar
Keatinge, J. D. H. & Cooper, P. J. M. (1983). Kabuli chickpea as a winter sown crop in northern Syria: moisture relations and crop productivity. Journal of Agricultural Science, Cambridge 100:667–680.CrossRefGoogle Scholar
Keatinge, J. D. H., Dennett, M. D. & Rodgers, J. (1985). The influence of precipitation regime on the management of three course crop rotations in Northern Syria. Journal of Agricultural Science, Cambridge 104:281–287.CrossRefGoogle Scholar
Keatinge, J. D. H., Neate, P. J. H. & Shepherd, K. D. (1985). The role of fertilizer management in the development and expression of crop drought stress in cereals under Mediterranean environmental conditions. Experimental Agriculture 21:209–22.CrossRefGoogle Scholar
Ketata, H., Halila, H., Deghaies, M., Maamourie, A. & Harrabi, M. (1979). La productione cerealiere en Tunisie. In The Proceedings of the Fifth Regional Cereals Workshop. Algiers, 5–9 May 1979. Ministry of Agriculture and Agrarian Revolution: Algeria, CIMMYT (Mexico City), and ICARDA (Aleppo, Syria). Vol. 1, 53–59.Google Scholar
Keulen, H. van. (1977). On the role of nitrogen in semi-arid regions. Stikstof No. 20:23–28.Google Scholar
Lindstrom, M. J., Koehler, F. E. & Papendick, R. I. (1974). Tillage effects on fallow water storage in the eastern Washington dryland region. Agronomy Journal 66:312–316.CrossRefGoogle Scholar
Loizides, P. (1979). Crop rotations under rainfed conditions in a Mediterranean climate in relation to soil moisture and fertilizer requirements. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, 5–10 May 1979, 23–38.Google Scholar
Matar, A. (1986). Annual Report 1985. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Mazad, A. & Hallajian, M. (1983). Crop-livestock interactions: information from a barley survey in Syria. In ICARDA Regional Farming Systems Workshop, May 1983, Aleppo, Syria.Google Scholar
McWilliam, J. R. (1981). Prologue: context and scope. In Soil Water and Nitrogen in Mediterranean-type Environments. Plant and Soil 58:vii–x.Google Scholar
Meigs, P. (1964). Classification and occurrence of Mediterranean-type dry climates. In Land Use in Semi Arid Mediterranean Climates. Arid Zone Research 26. Paris: UNESCO.Google Scholar
Miladi, S., (1983). The state of food and nutrition in the Middle East. In Interfaces between Agriculture, Food Science and Nutrition, 35–54 (Eds Miladi, S., Mahgoub, S. and Neate, P.). Aleppo, Syria: ICARDA.Google Scholar
Mokbel, M. G. (1985). Evaluation of nutritionally relevant indicators in villages in Aleppo Province, Syria, and their relation to agricultural development. PhD Thesis, University of Massachusetts, USA.Google Scholar
Newburg, R., Sleeper, J., Eighmy, T., Hanafi, M., Ream, H., Segal, J. & Hyslop, J. (1982). Rainfed agriculture sub-sector strategy, technical appendices. Morocco CDSS, USAID, Washington D.C.Google Scholar
Nordblom, T. L. (1983). Livestock-crop interactions: the decision to harvest or to graze mature grain crops. Discussion Paper 10. FSP. Aleppo, Syria: ICARDA.Google Scholar
Oram, P. (1979). Crop production systems in the arid and semi arid warm temperate and Mediterranean zones. In Soil, Water and Crop Production, 193–228 (Eds Thorne, D. W. and Thorne, M. D.). Westport, Connecticut: AVI Publishing Co.Google Scholar
Papachristodoulou, S. (1979). Socio-economic aspects of rainfed agriculture in Cyprus. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, May 5–10, 1979, 327–337.Google Scholar
Papendick, R. I. & Campbell, G. S. (1974). Wheat-fallow agriculture: why, how, when? In Proceedings 2nd Regional Wheat Workshop. Ankara, Turkey, 1974.Google Scholar
Pearcy, R. W. & Ehleringer, J. (1984). Comparative ecophysiology of C3 and C4 plants. Plant, Cell and Environment 7:1–13.CrossRefGoogle Scholar
Penman, H. L. & Schofield, R. K. (1951). Some physical aspects of assimilation and transpiration. Symposium of The Society of Experimental Biology V:115–29.Google Scholar
Perrier, A. (1973). Bilan hydrique de l'assolement ble-jachere et evaporation d'un sol nu, en region semi-aride. In Response of Plants to Climatic Factors, Uppsala, 1970, 477–487. Paris: Unesco.Google Scholar
Photiades, T. (1979). Integration of livestock with rainfed agriculture in Cyprus. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, 5–10 May, 1979, 108–117.Google Scholar
Ramig, R. E. & Rhoades, H. F. (1962). Interrelationships of soil moisture level at planting time and nitrogen fertilization on winter wheat production. Agronomy Journal 54:123–127.Google Scholar
Rassam, A. & Tully, D. (1986). Annual Report 1985. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Ritchie, J. T. (1983). Efficient water use in crop production: discussion on the generality of relations between biomass production and evapotranspiration. In Limitations to Efficient Water Use in Crop Production, 29–43 (Eds Taylor, M. H., Jordan, W. R. and Sinclair, R. T.). Madison: American Society of Agronomy.Google Scholar
Russell, R. S. (1977). Plant Root Systems: their Function and Interaction with the Soil, 19–29. England: McGraw Hill Book Co.Google Scholar
Saab, G. (1973). Lebanon. In International Association of Agricultural Economists. World Atlas of Agriculture. Vol 2: South and East Asia, 350–360. Novara, Italy: Institute Geografico de Agostini.Google Scholar
Sabet, Y. & Harris, H. C. (1986). Annual Report 1985. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Shepherd, K. D., Cooper, P. J. M., Allan, A. Y., Drennan, D. S. H. & Keatinge, J. D. H. (1987). Growth, water use and yield of barley in Mediterranean-type environments. Journal of Agricultural Science, Cambridge 108 (In press).Google Scholar
Simmonds, N. W. (1986). A short review of farming systems research in the tropics. Experimental Agriculture 22:1–13.CrossRefGoogle Scholar
Sivakumar, M. V. K. & Huda, A. K. S. (1983). Potential agricultural productivity in summer and winter rainfall areas. In Proceedings of the 1 7th Colloquium of the International Potash Institute, Rabat, Morocco, May 1983, 23–47.Google Scholar
Smith, A. J. (1979). The integration of livestock into rainfed agricultural systems. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, May 5–10, 1979, 139–152.Google Scholar
Smith, R. C. G. & Harris, H. C. (1981). Environmental resources and restraints to agricultural production in a Mediterranean-type environment. Plant and Soil 58:31–57.CrossRefGoogle Scholar
Soils Directorate/ICARDA (1984). Proceedings of the Soils Directorate/ICARDA Workshop on Fertilizer Use in the Dry Areas. March 26 th–29 th, 1984, ICARDA, Aleppo, Syria.Google Scholar
Somel, K., Mazid, A. & Hallajian, M. (1984). Survey of barley producers in northern Syria 1981/82. Volume III: descriptive statistics. ICARDA Research Report 12. Aleppo, Syria: ICARDA.Google Scholar
Stapper, M. & Goebel, W. (1985). Annual Report 1984, 50–53. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Taha, M. F., Harb, S. A., Nagib, M. K. & Tantawy, A. M. (1981). The climate of the Near East. In Climates of Southern and Western Asia. World Survey of Climatology, Vol. 9, 183–256. Amsterdam: Elsevier Scientific Publishing.Google Scholar
Tamini, S. A. & Young, J. R. W. (1980). Preliminary soil moisture studies at Hamman Al-Alil, Northern Iraq. In Proceedings of the FAO Regional Seminar on Rainfed Agriculture in the Near East and North Africa, Amman, Jordan, 5–10 May, 1979, 239–47.Google Scholar
Tanner, C. B. & Sinclair, T. R. (1983). Efficient water use in crop production: research or re-search? In Limitations to Efficient Water Use in Crop Production, 1–27 (Eds Taylor, H. M., Jordan, W. R. and Sinclair, T. R.). Madison: American Society of Agronomy.Google Scholar
Tennant, D. (1981). Effect of fallowing on cereal yield. Journal of Western Australia Department of Agriculture 22:38–41.Google Scholar
Thomson, E., Jaubert, R. & Oglah, M. (1986). Annual Report 1985. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Tully, D. (1984). Land use and farmer strategies in Al Bab: the feasibility of forage legumes in the place of fallow. ICARDA Research Report No. 13, Aleppo, Syria: ICARDA.Google Scholar
Tully, D. (1985). Annual Report 1984, p. 35. Aleppo, Syria: International Centre for Agricultural Research in Dry Areas.Google Scholar
Tully, D. (1986). Rainfed farming systems of the Near East region. In Proceedings of Workshop on Soi, Water and Crop/Livestock Systems for Rainfed Agriculture in the Near East Region, Amman, Jordan, January 1986.Google Scholar
Ulusan, A. (1980). Public policy toward agriculture and its redistributive implications. In The Political Economy of Income Distribution in Turkey, 125–167 (Eds Ozbudun, E. and Ulusan, A.). New York: Holmes and Meier.Google Scholar
UNESCO/FAO (1963). Bio-climatic map of the Mediterranean zone. Arid Zone Research 21. Paris: UNESCO.Google Scholar
Vlek, P. L. G., Fillery, I. R. P. & Burford, J. R. (1981). Accession, transformation and loss of nitrogen in soils of the arid region. Plant and Soil 58:133–176.CrossRefGoogle Scholar
Walker, G. K. & Richards, J. E. (1985). Transpiration efficiency in relation to nutrient stress. Agronomy Journal 77:263–269.CrossRefGoogle Scholar
Watson, A., 1974. The Arab agricultural revolution and its diffusion. 700–1100. Journal of Economic History, 34, No. 1.Google Scholar
White, H. (1963). Roman Agriculture in North Africa. Nigeria Geographical Journal 6:39–49.Google Scholar
White, H. (1970). Fallowing, crop rotation and crop yields in Roman times. Agricultural History 44:281–290.Google Scholar
Wong, S. C., Cowan, I. R. & Farquhar, G. D. (1979). Stomatal conductance correlations with photo-synthetic capacity. Nature 282:424–6.CrossRefGoogle Scholar