A Study on the Influence of Sludge WWTP from the Paper Industry on Growth and Development of Zea mays (Poaceae)

The sludge, which is produced from wastewater treatment facilities features concentration of harmful substances, including heavy metals. Therefore, before being used in agriculture, it is necessary to process the sludge in order to meet the requirements of the regulation concerning sludge utilization. The purpose of this study was to explore the possibility of growing corn using sewage sludge from the paper industry. A two-year experiment was performed with „Kneja 613“variety, which was grown in the field and fertilized by WWTP sludge, two standards - 1000 and 1500 kg/dka. The experiment was displayed on alluvial soil near the town of Stamboliyski (Southern Bulgaria). The following properties were monitored: germination, third and fourth leaves growth phase, phase of fifth and sixth leaves growth, stem thickness, number of the cobs and cob length. The results indicate the dependence of the amount of the deposited precipitate. The growth and development of plants grown at fertilization with 1500 kg/dka sludge showed much higher values of biometric properties than the control