The oasis agro-ecosystem is a combination of human settlement and a cultivated area (often a palm grove) in desert or semi-desert environment (Jaradat, 2011). Oasis expansion in arid regions is usually regarded as the opposite to desertification, referring to the process of transformation from desert to oasis in an arid region due to combined action of anthropic and natural factors (Wang, 2009). In MENA, approximately 4 million people live within the system. About 1.2 million ha of irrigated cropland are used for the production of dates, fodder, fruit trees, and vegetables. In addition, an estimated 2.7 million cattle, pastoralists within this system (FAO, 2008). Under the palm trees in the oases, a microclimate is established. Humidity, heat, and light are favorable for optimized usage of space for other crops (orange, pomegranate, vegetables, fodder and, cereals) to grow in an environment, where fertile soil is scarce (photo. xx).
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According to FAOSTAT, the highest producing countries of date palm are Egypt, Iran, Saudi Arabia, Algeria, Pakistan, Iraq, Oman, United Arab Emirates, and Tunisia (Figurexx). (FAOSTAT, 2012).
All oases of MENA region are allocated in the arid zone. Limited vegetation cover, water scarcity and salinity, are the main reasons for low organic matter in the system . Date palms need sufficient nutrients in proper balance for normal growth and development. The composition of date fruits during the various fruit development stages consumes a lot of nutrients, and such losses in the nutrient elements need to be substituted annually ( El Mardi, 2005). Ibrahim et al., (2013), indicated that the low level of SOC contents in the surface and subsurface soil layers is due to climatic conditions that favor the rapid decomposition of soil organic matter. He also found that nitrogen (N), Phosphorous (P), and Potassium (K) contents are low, as well as levels of available micronutrients. NPK fertilizers improve date palm growth, nutritional status of the tree, fruit set, and fruit quality (Soliman and Osman, 2013). Al Dekaili and AL-Dejaili (1989) reported that the average amount of N needed by date palm ranges from 1.8 to 2.7 kg year-1. K is also necessary for basic physiological functions, such as the formation of sugars, cell division, flavor, and color (Abbas and Fares, 2008). Microelements, such as Zn, Cu, Fe, and Mn play a vital role in improving the total yield and fruit quality of the date palm, whether used in organic or inorganic form (Hussein, 2004). Attallah et al., (2011) found that leaf spray boron (B) fertilizer application, combined with soil application of micronutrients fertilizers e.g. Fe, Mn and Zn enhances fruit ripening of date palm, and improves positive correlation between N, and K, Fe, Mn, and B. Dawoud and Fatima (2011) indicated that the application of elemental sulfur enhances the availability of other nutrients in calcareous alkaline soil, and results in high leaf elongation and high production of date. However, the amount applied should be determined based on whether it is used alone or in combination with manure or cover crops. Table xx shows the effects of inorganic and organic fertilizers on different varieties of date palm.