Impact of sewage sludge and composts prepared from sewage sludge on the content and uptake of macronutrients by straw of miscanthus sacchariflorus

The pot experiment was set up under the conditions of the hall of vegetation in 2002. The municipal sewage sludge and composts produced with the GWDA method in 2001 based on municipal sewage sludge with the 30% addition of structuring materials, in conversion to the dry matter, were used in the experiment. The pot experiment was set up with the split-split-plot method in three repetitions. The objects of the first factor were the doses of sewage sludge and composts (1 dose = 13 g, 2 dose = 26 g, 3 dose = 39 g, 4 dose = 52 g of dry matter in relation to the soil weight in the pot), the objects of the second factor were the types of organic fertilization (sewage sludge, 0,5-year compost prepared from sewage sludge, 1,5-year compost prepared from sewage sludge), objects of the third factor were the variants with and without nitrogen and potassium fertilization in the rates of 0.27 g N and 0.26 g K per pot. The experiment was conducted in Kick-Brauckmann's pots of 9 dm³ capacity in which 8 kg of soil were placed. The test plant cultivated in the experiment was Miscanthus sachariflorus. Seedlings of Miscanthus were planted in the first year of the experiment. The obtained results show that the content of macronutrients: nitrogen, phosphorus, potassium in straw of Miscanthus sachariflorus was not dependent on the type of organic fertilizers used in the experiment. However, supplemental nitrogen-potassium fertilization significantly increases the content of potassium in the test plant in all three years of research and nitrogen in the second year.

The conducted research shows that the uptake of macronutrients depended on the dry matter yield quantity and the content of a given element in the yield. Within three years the straw of Miscanthus sacchariflorus took up the most of potassium - 11.63 g from the pot and the least of magnesium 1.20 g from the pot. The amount of the absorption of nitrogen, phosphorus and magnesium by the biomass of Miscanthus sacchariflorus from the pot on the objects fertilized with organic fertilizers was the highest in the second year of the research, which was a result of mineralization of the applied fertilizers.