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.

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Improving water use efficiency of annual crops in the rainfed farming systems of West Asia and North Africa

SUMMARY We review the use and value of seasonal climate forecasting for agriculture in sub-Saharan Africa (SSA), with a view to understanding and exploiting opportunities to realize more of its potential benefits. Interaction between the atmosphere and underlying oceans provides the basis for probabilistic forecasts of climate conditions at a seasonal lead-time, including during cropping seasons in parts of SSA. Regional climate outlook forums (RCOF) and national meteorological services (NMS) have been at the forefront of efforts to provide forecast information for agriculture. A survey showed that African NMS often go well beyond the RCOF process to improve seasonal forecast information and disseminate it to the agricultural sector. Evidence from a combination of understanding of how climatic uncertainty impacts agriculture, modelbased ex-ante analyses, subjective expressions of demand or value, and the few well-documented evaluations of actual use and resulting benefit suggests that seasonal forecasts may have considerable potential to improve agricultural management and rural livelihoods. However, constraints related to legitimacy, salience, access, understanding, capacity to respond and data scarcity have so far limited the widespread use and benefit from seasonal prediction among smallholder farmers. Those constraints that reflect inadequate information products, policies or institutional process can potentially be overcome. Additional opportunities to benefit rural communities come from expanding the use of seasonal forecast information for coordinating input and credit supply, food crisis management, trade and agricultural insurance. The surge of activity surrounding seasonal forecasting in SSA following the 1997/98 El Nino has waned in recent years, but emerging initiatives, such as the Global Framework for Climate Services and ClimDev-Africa, are poised to reinvigorate support for seasonal forecast information services for agriculture. We conclude with a discussion of institutional and policy changes that we believe will greatly enhance the benefits of seasonal forecasting to agriculture in SSA.

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Review of seasonal climate forecasting for agriculture in sub- Saharan Africa

Adaptation of crop management to water-limited environments

In West Asia and North Africa, shortage of water limits wheat (Triticum aestivum L.) production. Current irrigation practices aim at maximizing grain yield, but achieve lower return for the water consumed. Maximizing water use efficiency (WUE) may be more suitable in areas where water, not land, is the most limiting factor. We examined the effects of various levels of supplemental irrigation (SI) (rainfed, 1/3 SI, 2/3 SI, full SI), N (0, 5, 10, 15 g N m -2 ), and sowing time (Nov., Dec., Jan.) on evapotranspiration (ET) and WUE of wheat. WUE was calculated for rain (WUE,), for total water (gross: rain + irrigation) (WUE g ), and for SI water only (WUE SI ). ET ranged from 246 to 328 mm for rainfed crops, with grain yield ranging from 130 to 270 g m -2 and total dry matter from 380 to 1370 g m -2 . Irrigated crops had ET of 304 to 485 mm, with grain yield of 170 to 500 g m -2 . The degree to which water supply limits grain yield was indicated by the ratio of pre- to post-anthesis ET (2.1-2.4:1). The SI treatments significantly increased WUE g : from 0.77 to 0.83 to 0.92 kg m -3 in November and December sowings for 1/3 SI and from 0.77 to 0.92 kg m -3 in November sowing for 2/3 SI. The highest WUE g and WUE SI were achieved at 1/3 to 2/3 SI. WUE was substantially improved by applying 5 and 10 g N m -2 , with little increase for higher rates. Delaying sowing had a negative effect on WUE for both irrigation and rainfed conditions. In this rainfed Mediterranean environment, WUE can be substantially improved by adopting deficit SI to satisfy up to 2/3 of irrigation requirements, along with early sowing and appropriate levels of N.

Water Use Efficiency of Rainfed and Irrigated Bread Wheat in a Mediterranean Environment

The effect of grazing by sheep during the late vegetative and early reproductive phases was measured on long-duration wheat crops in 2 experiments on farms in southern NSW. In both experiments, grazed and non-grazed crops were compared with different N-fertiliser strategies. In the first experiment, grazing 40 dry-sheep equivalents (DSE)/ha for 19 days increased grain yield from 2.30 to 2.88 t/ha in a season with a dry early spring. The second experiment, in a more favourable season, compared 6 durations of grazing by an average of 32 DSE/ha. The effects of grazing varied from no yield reduction with 15 days of grazing to a reduction from 5.97 to 3.98 t/ha with 51 days of grazing. In both experiments grazing caused slower crop development, with about 1 day’s delay in anthesis and maturity for every 4–5 days of grazing. Different patterns of water use by grazed and non-grazed crops, combined with delayed development, explained much of the effects of grazing on yield. The soil accumulated more water during grazing, which was used during grain filling when water-use efficiency for grain production was high. Delayed development also allowed grazed crops to respond to later rain. In the second experiment, grazing resulted in a net loss of 38 kg N/ha from the crop. Despite reduced N levels, the grazed crops showed no greater ability than grain-only crops to recover fertiliser N. The effect of the low recovery was that N removed during grazing was not efficiently replaced by fertiliser.

Effects of grazing on wheat growth, yield, development, water use, and nitrogen use

Grain yield responses of barley and durum wheat to split nitrogen applications under rainfed conditions in a mediterranean environment

Differences in response of winter cereal varieties to applied nitrogen in the field II. Some factors associated with differences in response

Production of green feed and grain from grazed barley in Northern Syria

Differences in response of winter cereal varieties to applied nitrogen in the field. I. Some factors affecting the variability of responses between sites and seasons.

W.K. Anderson

Papers

Grain yield responses of barley and durum wheat to split nitrogen applications under rainfed conditions in a mediterranean environment

Differences in response of winter cereal varieties to applied nitrogen in the field II. Some factors associated with differences in response

Production of green feed and grain from grazed barley in Northern Syria

Differences in response of winter cereal varieties to applied nitrogen in the field. I. Some factors affecting the variability of responses between sites and seasons.

Plant populations for triticale in a mediterranean environment