ABSTRACT
This chapter presents a different approach to plant nutrition from that found in the technical literature. Adequate nutritional control in greenhouse production represents one of the greatest opportunities for significant advances in the future. There are two primary factors in nutrition that determine nutrient supply: intensity and capacity. The first refers to the concentration of nutrients in the substrate solution. The second is the ability of the substrate to replenish a particular nutrient as it is removed from the solution. Cation exchange capacity is one measure of the capacity factor or the ability to hold exchangeable cations. There are three major parts to greenhouse nutrition control: visual diagnosis of the crop, tissue analysis, and soil analysis. The presence of salts in the irrigation water will influence ability to manipulate nutrition. Newer systems for automatic control can take into account variations that may occur in water supply quality.
