Water and Agricultural Crop Productivity

The ultimate objective of agronomic agriculture is to attain the highest potential yield per unit area of land. Several economic inputs are involved; however, the prime limiting factors are physiochemical. Crop yields are a measure of that portion of the plant which has the priority economic value. Water is a major factor in crop yield. Water is a major constituent of the cell protoplasm of actively growing plants. It is involved directly in a number of chemical reactions occurring in protoplasm, most notably the process of photosynthesis. Plants are an integral segment of the hydrologie cycle. In the cycle, the transformation of water from the liquid directly into the vapor phase is through the processes of evaporation. Soil serves as a water-storage reservoir for plant usage during periods of nonprecipitation. As water is transported from the soil to the atmosphere through the plant it moves along an energy gradient, from higher to lower.