Impact of Sewage Sludges in Combination with Various Amendments on the Nitrogen State of Leached Chernozem

In a 3 months model experiment, the effect of application of sewage sludge (SS) at doses of 40 and 80 g/vessel (in terms of dry mass corresponds to 5 and 10 t/ha) in combination with straw, kieselguhr and sapropel, on the nitrogen state of leached, slightly eroded chernozem, was studied. It is shown that the addition of kieselguhr and sapropel to SS, unlike of straw, improves the parameters of the soil nitrogen state. A raise of the SS dose leads to a significant increase of the alkaline hydrolysable nitrogen content. The ability of ameliorants with SS to enrich the soil by mineral nitrogen can be arranged in the following descending row: suspended kieselguhr dry kieselguhr sapropel SS severally straw. A double dose of SS does not differ significantly from a single dose in terms of its influence on the contents of total and mineral nitrogen, humification and soil acidity; the use of high doses of SS is rational for waste disposal.