Nitrification ability of slow releasing nitrogen fertilizers

Yanka Kotopanova, Dimitar Slavov

Abstract: Various products of polymerization of carbamide or formaldehyde are used for their property to release nitrogen slowly. Such products have been synthesized by chemical companies abroad and in Bulgaria. These compounds are known as long-acting or slow-nitrogen-releasing fertilizers (SNRF). Important parameter that determines the efficiency of these fertilizers is their nitrification ability and the nitrogen release rate. The present study was undertaken to test the nitrification ability of three different SNRF and to estimate the opportunities for their application to ornamental plants To determine the portion of nitrogen that is converted to nitrate and ammonium form, two SNRF synthesized on carbamide-formaldehyde base (powdered fertilizer containing 40.1% nitrogen of which 19.9% soluble in cool water and 6.8% soluble in hot water and, liquid fertilizer, containing 26% nitrogen, of which 21.2% soluble in cool water and 5.4% soluble in hot water) were exposed for nitrification at controlled temperature and air humidity. At the same conditions capsulated fertilizer (carbamide granules coated with inorganic and organic substances) containing 39.4% nitrogen was also tested for nitrification. For comparison, carbamide containing 46.3% nitrogen was used. The experiment was carried out as follows: 100 g soil were mixed with 30 mg nitrogen from the fertilizers, moistened to 60% and put in previously calibrated plastic pots. The pots were placed in thermostat at 25–26ºC throughout. The ammonium and the nitrate forms of nitrogen were determined at the 1, 3, 6, 9, 12, 15, 18 weeks of the experiment. After recording the evaporation rate at the indicated times, the soil was watered with deionized water to maintain constant 60% humidity. The amounts of nitrate and ammonium nitrogen were analyzed in a soil filtrate by using autoanalyzer.

Keywords: nitrification; nitrogen fertilizers; washing degree

Date published: 2017-07-26