Мелиорация и гидротехника (Feb 2024)
Impact of sewage sludge on test plants and agrochemical properties of soils
Abstract
Purpose: to assess the fertilizing value of sewage sludge. Materials and methods. The material used for research was sewage sludge from municipal wastewater treatment plants in Novocherkassk with a three-year stay period on the sludge map. The research was carried out as a part of a vegetation experiment on soils selected from agricultural lands in Aksai district Rostov region. According to the analysis, the soils are non-degraded, non-saline with a low humus content and an average nutrient content. The granulometric composition of soils is dominated by coarse silt fractions. Sewage sludge, on the contrary, is characterized by a high content of organic matter and nutrients; sand fractions predominate in the granulometric composition. Radish and watercress were used as test plants as they were the most sensitive to the presence of contaminants. Soil bioproductivity was assessed by seed germination, total biomass, and average biomass per plant. Results and discussions. The best germination of plant seeds was noted in variants with the application of sewage sludge to soils in comparison with both the control and the variant of using fertilizers in similar doses of the active substance. Under the influence of sewage sludge, changes in the qualitative composition of soils were noted: the amount of nitrates, phosphates, calcium ions and sulfates increased, and the content of organic matter increased. Conclusions. The positive effect of sewage sludge on plants has been determined: the radish yield increased by 55 % with the use of sewage sludge, and by only 10 % with the use of azofoska (nitrogen-phosphorus potassium fertilizer); the watercress yield increased by 29 % against the background of the use of sewage sludge and by 2 % against the background of the use of azofoska. In variants with the application of sewage sludge, an increase in the content of organic matter by an average of 30 % is observed. In soil samples with sewage sludge, an increase in the nitrogen content by 30–59 %, phosphorus by 67–78 % compared to the control was noted, and when azofoska was added, in comparison with control samples, the amount of nitrogen increased by 5–23 %, and phosphorus by on average by 50 %.
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