A Current Perspective On Micronutrient Constraints to Crop Production in Mediterranean-Type Agriculture.

Agricultural production in the Mediterranean region is mainly rainfed and is limited by rainfall, and while irrigation is increasing, there are limitations to irrigation water. Under both conditions, crop yields can only be increased with an adequate supply of nutrients. Nitrogen and, to a lesser extent, phosphorus are invariably needed as chemical fertilizers. In recent decades, an awareness has grown of the importance of micronutrient constraints in crop production.  Micronutrient deficiency is conditioned by the calcareous nature of the region’s soils, especially for zinc and iron, as well as low soil organic matter, which also affects boron deficiency. These soils have been cultivated for millenia, and depleted of micronutrients. What little micronutrients were added came from animal manures. Ironically, the Mediterranean region has areas that are characterized by micronutrient excess, especially in the case of boron. While micronutrient deficiencies can be ameliorated by fertilization, toxicity can only be managed by crop adaptation. Since the importance of micronutrients was realized, much has been done in establishing a broad picture of the chemical behavior of micronutrients in soils, and the relationships with crops, as well as implications for human and animal health. With intensification of agricultural proiduction, micronutrients will assume greater significance in the future. This presentation gives a broad overview of the various aspects of micronutrients in Mediterranean soils and highlights challenges to transferring existing information on micronutrients into practice at the growers’ level.