Mission effectuée en Syrie du 05 au 12 mai 2007 pour participer à l'atelier Conservation agriculture for sustainable land management to improve the livelihood of people in dry areas

The high population growth rate, the degradation of agricultural lands and the scarcity of water have raised some doubt about the continuous suitability of the dominant agricultural systems in the dry lands of the Arab region. In face of these environmental and economic challenges and even though there are currently local solutions, there is a need to reconsider those classical agricultural systems and try new agricultural systems which may help preventing soil degradation and increasing its productivity. Conservation agriculture (CA) is considered a promising solution for the region, but looked upon sceptically because of lack of information and because of the varying definitions and terms used (no-tillage, direct planting through a soil cover, conservation tillage, etc.). The system risks not to be accepted by farmers, if the (economical) benefits are not superior to those of the conventional systems, and if it is not supported by agricultural policies and scientific research. Great efforts by all partners and stakeholders are required to implement this system which remains a real hope for sustainable agriculture in the Arab countries, in rainfed as well as in irrigated agriculture. Keys words: system CA, aridity index, adoption, rainfed agriculture, water resources Introduction As a result of the prevailing rainfall pattern and soil types, the semi-arid and arid areas constitute almost 90% of the entire area (14.3 million km) of the Arab region (ACSAD, 2004), and are among the most fragile and unstable ecosystems in the world. The rapid population growth (2.6% per annum) increases the pressure on the natural resources (AOAD, 2004), and consequently the degradation of land and water resources is alarming. This situation implies the need for a compromise between sustainable agricultural production that conserves the environment, and provides income to farmers at an acceptable productivity and a performance with a feasible cost for the state. Conservation agriculture, although it is perceived in the region with great caution due to the lack of information and to the ambiguity of the definitions given to it so far (no-tillage, direct drilling/seeding, drilling/seeding through a vegetative cover), could be the solution for agricultural production without degrading the natural resources. The system, however runs the risk of not being accepted Conservation Agriculture (CA) in the Arab World between Concept and Application Abdelouahab Belloum Conservation Agriculture Program The Arab Center for the Studies of Arid Zones and Dry Lands (ACSAD) P.O. Box 2440, Damascus, Syria Belloum_a@yahoo.fr; Tel. : +963 11 5743063 by the farmers if the direct benefits it provides are not greater than, or similar to those offered by conventional agriculture. The dissemination has to be supported by appropriate agricultural policies and participative research programmes that deepen the knowledge of the biophysical mechanisms underlying the functioning of the system and the conditions for its adoption by farmers (CNEARC CIRAD-CA, 2001). An unfavourable geo-climatic context An unfavourable climate, marked by spatio-temporal irregularities, coupled with growing tensions on land and water resources, stresses the importance of a progressive orientation towards an economically feasible and environmentally viable agriculture. Where soils were subjected to intensive agriculture, physical degradation followed automatically. Establishing a well managed system of conservation agriculture allows producers to increase and maintain soil organic matter and soil life. As such, the impact on soil stability, reduction of erosion, and increased water use-efficiency are remarkable (Blanchart et al., 2000). The geo-climatic context of the region is mostly Mediterranean, characterised by a relatively temperate (rainy) season during which the cyclonic disturbances bring rain, sometimes substantial events, especially on hills. This is followed by a dry period and calm weather (Belloum, 1992). The rainfall pattern reflects the same trends and tendencies of the Mediterranean climate (alternating dry and wet periods). It is essential for the presentation of the rainfall distribution and its pattern to determine two indices that translate the nuances of the pattern and the inequality of the distribution. The index P/n is a direct function of the average annual rainfall (P) and is inversely proportional to the number of rainy days per year (n). In fact, it expresses the degree of the uneven rainfall distribution throughout the year. A high value of P/n indicates a concentration of rainfall or precipitation. A small value of this index indicates simply a rainfall distribution which is staggered over time; which is not the case of all the sites taken as example (Fig. 1). The index S/P reflects perfectly the rainfall concentration in a period of maximum precipitation(S corresponding to three consecutive months during which the accumulated rainfall is highest). But its major importance lies in the fact that it explains a climatic characteristic, e.g., if the rainfall is concentrated Abdelouahab Belloum 14 Figure 1: Index P/n off the unequal rainfall distribution over sites in a single season, rains are in most cases heavy and torrential, having a high erosivity index (Fig. 2). The figure shows that all the selected sites had an S/P index close to 0.5, which means that 50% of the rainfall was concentrated in one period. Theoretically, the rainfall would be evenly distributed if the index value approaches 0.25 as opposed to a concentration where the index value approaches 1. There are many indicators that can explain/express the climatic situation. Among these indices is the aridity index of De Martonne that characterises the climate of a region, but allows, above all, the delineation of the zones requiring irrigation (Belloum, 1991). This index is a function of the mean annual precipitation (Pa in mm) and mean annual temperature in °C, (I = Pa/ (T+10). The determination of monthly aridity indices (Am) based on a series of observations, within a sample area, allows a realistic definition of the irrigation period (Fig. 3). Conservation Agriculture for Sustainable Land Management 15 Figure 2: Index S/P for rainfall concentration over sites Figure 3: Monthly aridity indices of De Martonne and the irrigation seasons. (for coloured picture see annex #3, p.281). A m In de x Abdelouahab Belloum 16 In fact the Arab region lies within a transitional climatic region with a double affiliation with respect to seasons. In summer, it is a subtropical climate marked by increased drought, and in winter, the tendency is more towards the temperate or moderate areas, however with torrential rains. Under these conditions, the natural constraints limit the intensification of the land use in the region. This is expressed mainly by inundations during the rainy periods which prevent the use of lower lying areas, and by severe soil erosion on slopes, which not only results in a decline of soil fertility but also in the sedimentation of dams and lakes. Inappropriate agricultural practices, such as ploughing down-slope, intensify these processes. The hydrological deterioration of these areas where rainfed agriculture prevails combined with anthropogenic actions is illustrated schematically in figure (4). Gréco (1979) said in his handbook for the protection and restoration of major soils in Algeria: “In this country of 28 million hectares, besides the Sahara, we estimate that about 13 million hectares or 45% of the total area are subject to erosion and should be placed under different regimes and forms of protection and rehabilitation. This mountainous country with steep slopes and an increasingly growing population, a livestock concentration well above the carrying capacity, looses its arable land at a striking rate”. A critical state of water resources The surface water resources average in the Arab region is estimated at 205 billion m/y. About 70% of this water comes from outside the region. The ground water resources are distributed over large basins and aquifers, some of which are trans-boundary. The estimated reserves of the ground water resources are ~ about 7730 billion m, with only 35 billion can be exploited nowadays (AOAD, 2005). The annual recharge of these resources is about 42 billion m. Non-conventional water resources including the sewage drainage and industrial waste water and the desalinated water of desalinisation installations, are estimated at around 7.5 billion m. Drainage water constitutes 5 billion m, and the desalinated water is about 2 billion m. However, there is a remarkable tendency in the Arab world to reuse sewage water. The statistics on the use of water resources in the Arab region indicate a volume of about 191 billion m. Agriculture accounts for 89% of the use, domestic use for about 6% and industrial uses for about 5%. Despite this high use for agriculture, about 50% of the agricultural products are imported from outside the Arab region, as the food requirement in the region increases rapidly proportional to the population. The volume of water utilised for agriculture is estimated at 169 billion m, of which 147 billion m are used for surface irrigation by gravity, with a water use-efficiency of only 38% (water use efficiency is the ratio of the crop water requirements to the total water supplied to the crop). The losses are estimated at 91 billion m. It is evident that the increase of the water useefficiency in agriculture is of first priority. Figure 4: Hydrological and anthropogenic degradation in slopy areas. (for coloured picture see annex #3, p.281). New cropping systems and cultural practices have to be explored and adapted to the regional situation. Conservation agriculture represents one of the appropriate solutions for this specific context (Belloum, 2003). The indicators for land resources indicate that the area of agricultural lands for the year 200