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Conventional tillage coupled with monocropping and limited recycling of crop residues along with increased pressure from human and livestock population has led to the degradation of the soil, water resources, and the environment in the Middle East and North Africa (MENA). Conservation Agriculture (CA) considered as "climate-smart" agriculture, strives to achieve acceptable profits along with high and sustained production levels while concurrently conserving and regenerating soils and protecting the environment. The objectives of this paper are to review and synthesize available findings on CA, its past trends, current opportunities and challenges, evidence on potential benefits from its adaptation, to discuss its future outlook, and to make relevant recommendations for interventions and novel research needs for its wider diffusion in the region. In MENA, major research on CA has been mainly conducted in Morocco, Tunisia, Iran, and Syria, while Jordan, Lebanon, Iraq, Egypt embarked CA research fairly recently. About 25-40% out of the 53 million hectares total arable land is estimated to be suitable for CA in the region. In recent years a growing number of studies carried under a range of climatic, soil, management and cropping conditions in many countries of MENA reported several benefits including higher and more stable yields and profits, reduced risks of crop loss, labor requirements, soil erosion, and improved soil moisture and quality under CA system. Despite its benefits, adoption of CA in MENA is still very low for various reasons including: lack of affordable and well-adapted seeders, the complexity of the CA system which posed a major challenge for mostly uneducated farmers to comprehend, ill-conceived policies that promote cereal intensification hence inadvertently promote monocropping, tradeoffs between residue retention and livestock feed, lack of adequate policy and institutional framework and incentives to enhance farmers' adoption, and the private sector's active involvement in the dissemination of CA. The wider acceptance of CA requires the development of affordable and versatile no-till seeder alongside the implementation of integrated crop management practices. CA-based bundled agronomic management practices must be tailored to the biophysical and socio-economic environment. Finally, effective strategies for upscaling CA in MENA has to be developed by taking into consideration the unique features of the region. Despite the daunting past adoption trends and current challenges, we predict a bright future for CA in the region due to several factors including: rising energy prices and wage rates, the emergence of younger and more educated farmers, the advent of climate change, the increasing awareness on the degradation of land and water resources among farmers and policy makers, changes in dietary preferences subsequently increasing trends in demand and prices of legumes are expected to increase the desirability of CA and enhance its wider diffusion in MENA. [ABSTRACT FROM AUTHOR]

• Wind erosion is the most environmental threat in arid and semi-arid regions. • Aridisols of south eastern Tunisia showed high values of wind erodible fraction EF. • Prediction equations of EF are not applicable for Aridisols of Tunisia. • The developed prediction equation of EF is largely different than other over world. • The developed equation showed that sand and CaCO 3 contents controlling soil EF. Wind erosion is a serious environmental threat. However, for Northern Africa estimates or predictions of the wind erodible fraction (WEF) in arid soils are rare. This study was conducted to (i) compare the flat sieve (WEF fs) and the Fryrear equation (WEF c) in order to estimate WEF (ii) fuse the directly measured WEF fs values to other measured soil parameters, i.e. soil organic matter (SOM), carbonate (CaCO 3), sand, silt and clay content, to obtain a new improved WEF equation prediction. Samples were collected at ten locations near Gabès (Southern Tunisia) at three depths (0–2.5, 2.5–5 and 5–15 cm) in cultivated or native soils. The obtained WEF fs were>80% and therefore the soils would be classified as highly wind erodible (WEF > 50%). The lowest WEF fs values were found in the cultivated soils (82.5%), ranging from 82.5 to 96.9%. Our WEF fs estimates were positively correlated to sand (r = 0.78; p < 0.001), but negatively correlated to CaCO 3 content (r = -0.82; p < 0.001). Interestingly, neither SOM nor clay content was strongly related to WEF fs. However, the WEF fs in cultivated soils was significantly linked to ∑(SOM + clay content). The Fryrear estimation predicted all WEF c values to be less than 60%. This clear mismatch to our data relates to CaCO 3 presence, high sand and low SOM content in our Tunisian soils, when compared to US soils used to establish the Fryrear method. Therefore, we established a new equation for the wind erodible fraction, WEF mod (%) = 125.83–0.59*Clay(%) − 0.22*Silt(%) − 0.25*Sand(%) + 0.29*SOM(%) −0.69*CaCO 3 (%) (r = 0.85; p < 0.001). In the studied regions of Tunisia, this equation predicts much better soil WEF. The present paper is a first study to improve WEF estimation and prediction in arid North Africa. Better predictions of WEF are crucial in combating wind erosion of soils both in North Africa and in comparable soils globally. [ABSTRACT FROM AUTHOR]

• CA system led to 307 kg/ha (35 %) higher wheat yield than conventional practices (CP). • CA system led to $99/ha (44 %) higher gross margins than CP. • Adoption of any one or two components of CA also led to higher benefits than CP. • Complete CA system led to higher benefits than partial adoption of its components. • Adoption of any two components of CA led to higher benefits than any one component. Despite several efforts for its dissemination, adoption of conservation agriculture (CA) in the Middle East and North Africa (MENA) region is low – causing some to wonder if an incremental approach for adoption of its three components would prove more effective. In this paper, we apply the endogenous switching regression model to a nationally representative sample of 1901 wheat fields in Morocco to analyze the impacts of partial or full adoption of all three components of the CA system. We also employ an ordered probit model to identify the determinants of partial and full adoption of CA. Model results show that adoption of the complete CA system leads to 307 kg/ha (35 %) higher yields, US$99/ha (44 %) higher gross margins, and 23 kg/capita/year (38 %) more consumption of wheat relative to the conventional system. Our results also show that adoption of only two principles of the CA system leads to higher benefits in all the livelihood indicators listed above compared to adoption of only one or none of the principles. Likewise, adoption of only one principle is more beneficial than the conventional system. Along with biophysical and environmental benefits documented elsewhere, our results demonstrate that the CA system can provide large economic, social, and food security benefits both at individual household and national levels. Therefore, wider diffusion of the full CA system involving zero tillage (ZT), crop rotation, and crop residue retention has potential to sustainably improve the viability of agriculture in the drylands of Morocco and other similar countries in the MENA region. Given that the CA system is complex and knowledge-intensive, transition from the conventional system to CA requires the following: (1) flexibility to let farmers incrementally adopt one or more of the CA components, learn at their own pace, use some of the benefits, and improve it over time to exploit the full potential of the CA system with close follow-up and technical support from experts and extension specialists; and (2) sustained policy and institutional supports that provide incentives for farmers to adopt and for the private sector to be actively involved, especially in service provision. [ABSTRACT FROM AUTHOR]

Conservation agriculture (CA) involving zero tillage, crop diversification, and residue retention is considered a panacea for several interrelated problems in agricultural production. However, in the mixed crop-livestock production systems of the drylands, crop residues have great significance as sources of animal feed, posing a major challenge in the promotion of CA. While the economic benefits and the drivers of adoption of zero tillage and rotation have been well documented, the literature on the economics of residue retention (RR), especially in the drylands, is scanty. By applying the endogenous switching regression model to a case study of 2296 wheat fields in Morocco, this paper provides evidence on the socio-economic impacts of residue retention. Between 30% and 60% and above 60% of crop residues were retained respectively on 35% and 14% of wheat fields. These levels of residue retention led to 22% and 29% more yields, 25% and 32% higher gross margins and 22% and 25% more consumption of wheat, respectively. Retention of above 60% residue reduces both downside risk and variability of yield while lower levels of residue retention have mixed effects. Residue retention is economically and biophysically beneficial even for owners of livestock as the monetary value of the additional grain yield more than offsets the cost of purchasing an equivalent amount of feed from the market—all providing good economic justification for residue retention. Our findings show that economic reasons are not barriers for adoption of residue retention, but risk factors and absence of alternative feed sources might. The policy implication of our results is that there are high incentives for Morocco and other similar countries in North Africa and West Asia to invest in the development and/or import of alternative feed sources, introducing crop insurance, and raising the awareness of the economic, biophysical and environmental benefits of residue retention among farmers. [ABSTRACT FROM AUTHOR]

In this paper, a new approach for mapping polygenic depressions colonised by vegetation is presented. These spatially periodic vegetation patterns situated in the arid areas of North Africa are known locally as "Dayas". The mapping of these structures is an important component in monitoring their evolution which can be regarded as an indicator of socio-environmental conditions. For this purpose, a method based on satellite image analysis is proposed. First, Landsat Thematic Mapper image inspection is performed to highlight the vegetation spots using the Normalized Difference Vegetation Index (NDVI). Then, a Differential Morphological Profile (DMP) which includes both spectral and morphological information, is built for each NDVI pixel. We adapt the F-Score technique combined with the SVM classifier, to select and classify the most effective DMP images in order to extract the Daya's signature. Using feature selection, overall classification accuracy reached 97.8% with a kappa value of 95.61 but also reduced the dimension of the DMP vector. Dayas' morphological and vegetation characteristics are related to their degree of evolution. Furthermore, we categorise categorise the 170 extracted Dayas into three classes according to their size. On the resulting map, each class corresponds to a specific morphological and vegetation evolution stage. • The established methodology allows Dayas identifying in semi-arid areas. • Differential Morphological Profile is a powerful tool for spots vegetation mapping. • Size-based classification of Dayas enables a chronological distribution. • F-Score combined with SVM for feature selection improves classification accuracies. [ABSTRACT FROM AUTHOR]