Effect of fertilization with wastewater sludge on the development of Betula pendula seedlings under experimental conditions

Abstract

The aim of the experiments was to elucidate the influence of the treatment of alvar and peaty soils with different doses of wastewater sludge on the development of seedlings of silver birch (Betula pendula) under experimental conditions. Sludge from Tallinn Wastewater Treatment Plant used had passed methane fermentation and centrifugal drying. The content of dry matter in the sludge was 50.7%. The concentration of nutrients in the sludge was high: N 2.06%, P 2.76%, and K 0.28%. The experiments were conducted on the territory of Tallinn Botanical Garden. For experiments 10 L plastic pots containing soil and peat mixtures with different concentrations of wastewater sludge (8.9; 26.6, and 44.3 kg/m 2 d.m.) and control variants were used. As a rule, treatment with sludge causes stress in seedlings during the period after planting inhibiting their growth and development. As compared to peat substrates, mineral soils are notably more sensitive towards treatment with wastewater sludge, and stress in plants in the first year is caused by considerably smaller doses of sludge. In spring 2005 the variant with 5 kg wastewater sludge added to soil per pot died completely; also the variants with 3 kg sludge added to soil and 5 kg sludge added to peat should be regarded as dead. In the second year a positive effect of wastewater sludge was observed in the peat variants. By the end of the second year of growth the morphological parameters of different variants changed significantly. The dry mass was the greatest in the variants with 1 kg and 3 kg wastewater sludge added to peat, exceeding the control variant 4.1 and 3.7 times, respectively. In all the variants the proportion of roots in the total dry mass increased.