Analyzing Greenhouse Growth Media by the Saturation Extraction Method

Abstract

Abstract Growth media used for growing containerized plants in greenhouses have changed greatly since the initiation of the Spurway test procedure (8). Well-aggregated field soils gradually gave way to mixtures of soil and manufactured coarse amendments and eventually to soilless growth media. Along with these changes in growth media composition came changes in physical and chemical properties—some desirable, some not so desirable. Field soils generally have a high-nutrient capacity value and a low-intensity factor. The level of the capacity factor has decreased as the change in growth media composition has taken place. Geraldson (1-3) developed an “intensity and balance” analysis system for the unique, sandy soils of Florida; soils that provide little buffering capacity. He found the concentration (intensity) and balance of nutrients in the soil solution to be important when the capacity factor was small. Similarly, the concentration and balance of nutrients in the solution phase of greenhouse growth media today have become important to plant growth and quality.