Soil and Fertilizer Phosphorus and Crop Responses in the Dryland Mediterranean Zone

As we approach the end of the century, the disparity between the rich and poor nations of the world is startling. While poverty knows no climatic or geographical boundary, a disproportionate number of the less well-off are concentrated in dryland or rainfed areas of the world. There, poverty has many bedfellows; low literacy levels, underemployment, small land holdings, limited and poor quality resources, and, consequently, low agricultural output. Because of over-stocking and poor grazing management, soil degradation is an inevitable consequence and one that undermines a country’s agricultural production capacity. This phenomenon is apparent in virtually all dryland areas of the world (Majeed, 1986). While soil degradation is evident in such places as diverse as Brazil and China, most countries of Africa are affected. Though the sub-Saharan Sahel has attracted attention because of disastrous famine in the past two decades, the North Africa region is just as much threatened. Indeed, the problem is common in West Asian countries as well. It is ironic that water, a scarce resource, which dictates the course of man’s fortunes in dryland areas, can also cause a depletion of the soil resource, if not managed properly.