Studies on mineralization of nitrogen from slow-acting nitrogen fertilizers — urea-aldehyde-condensates

Abstract

Summary Data are reported in this article concerning the use of the general mineralization process as a method for characterizing the slow-acting nitrogen fertilizers - urea-aldehyde condensates. Investigations were carried out in a model incubation experiment with different soil samples, such as calcareous chernozem, grey forest, brown forest, and cinnamonic podzolic soils, and the following urea-aldehyde preparations: Nitroform, Floranide, Izoboutiliden-diurea (IBDU), and HTI-2 (the laboratory sample synthesized at the HICE, Sofia) were used. On the basis of the results, obtained from the separate processes taking part in mineralization and transformation of the nitrogen component (ammonification, nitrification, gaseous losses of niitrogen, biological immobilization), a tentative balance sheet of nitrogen was computed that allowed the quantity of undecomposed substance, introduced through urea-aldehyde preparations, to be also determined. There was found that the data for the general mineralization of nitrogen are the best illustration of the rate of release of mineral nitrogen, characterizing completely the properties of the slow-acting nitrogen fertilizers — urea-aldehydes — under conditions of soils of different properties, as compared to ammonification and nitrification characteristics. The highest mineralization activity and a well expressed effect of slow action, as regards plant requirements according to stages of development, were shown by IBDU, followed by Floranid, Nitroform, and HTI-2.