The utilization of phosphorus from purified municipal sewage by cultivated plants

Abstrakt

The aim of this study was the agrochemical evaluation of purified municipal sewage as a source of phosphorus - one of the basic nutrients. The study was based on the chemical analysis of plant material obtained from a strict two-year pot experiment. The soil material used for the ex-periments was collected from the depositional layer of the peak-muck soil made of low moor peat (organic soil) and from podzolic soil with granulometric composition of light loamy sand (mineral soil). The test plants were spring barley, spring rape and sunflower. The application of purified municipal sewage influenced the increase of phosphorus content in the dry plant matter. The increase was more conspicuous in plants grown on the organic soil. This justifies the statement that sewage can be a source of phosphorus for plants, which is comparable with mineral fertilizers. The plants watered with sewage took a little less phosphorus than those fertilized with mineral salts. Also fertilization with sewage supplemented with salts in most cases affected the absorption of this component less effectively than fertilization with mineral salts in the optimum rate. When equivalent amounts of phosphorus were applied, the test plants utilized the analyzed component from mineral fertilizers to a greater extent than that from purified municipal sewage. Similarly, the application of sewage and supplementing it with mineral salts up to the level that was assumed as optimum contributed to the decrease of the degree in which phosphorus was utilized in comparison with that found in the treat-ments where mineral salts in the optimum rate were exclusively used. Among the tested species, spring rape is the most suitable for thorough sewage treatment.