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The effect of equivalent amounts of hydrochloric and sulfuric acids and calcium phosphate on lettuce yield components.
The increase in costs and decrease in availability of chemical P fertilizers has resulted in increased efforts of finding new ways of rendering residual soil P available to plants. It has been found that acidifying certain calcareous soils, low in plant available P but containing a large amount of acid/soluble P, has resulted in improved P availability and plant yields. The majority of the soil acidification studies have been concerned with the use of elemental S, which will slowly oxidize to form H2SO4 under proper soil pH, moisture, aeration, temperature, and in the presence of S oxidizing bacteria. When H2SO4 or some other acid such as HC1 is applied directly to the soil, its chemical reaction with the soil is immediate and complete. This reaction is considered desirable as a greater concentration of P is immediately rendered available to plants. The objectives of this research were to study the ability of HC1 and H2S04 applications to solubilize native and residual soil P on five Fresno County, California, alkaline calcareous soils and to measure this effect by plant yield and P uptake of lettuce (Lactuca sativa _L. ) .