Symbiotic Nitrogen Fixation and Phosphorus Acquisition. Plant Nutrition in a World of Declining Renewable Resources

Abstract

Since 1960, the world’s population has doubled to 6 billion people. During the next 40 years, the population is projected to increase and stabilize at 8 to 9 billion people (Table I). In the 1960s, agricultural specialists predicted that food production would not keep pace with the burgeoning population growth. However, unforeseen advances in plant germplasm improvement (Green Revolution), the unprecedented use of fertilizers, and expanded use of irrigation not only allowed food production to keep up with but also to outpace population (Waggoner, 1994; Dyson, 1999). Forty years ago, 25% of the world’s population went to bed hungry each day. Since that time, improvements in food production have reduced that hungry percentage to about 17% even as population doubled. Yet, today 0.8 to 1.0 billion people are chronically undernourished (consume fewer than 2,000 calories per day), 100 million preschool children have a vitamin A deficiency, and 400 million women between the ages of 15 to 49 have an iron deficiency leading to anemia (Conway and Toenniessen, 1999). Even in the developed world, micronutrient deficiency due to poor dietary intake is a major problem among the poor. Although on a global scale food production is adequate and consumer prices for food remain low, on the local scale offending discrepancies in food production and availability are causes for concern (Waggoner, 1994; Dyson, 1999).