Effect of fertilization with nitrogen and microelements on the content of total organic carbon and dissolved organic carbon in Luvisols

The aim of the paper has been to investigate the effect of fertilization with nitrogen and microelements (Se and Cu, Mn, Zn) on the content of carbon (TOC) and nitrogen as well as dissolved organic carbon (DOC). The study was performed based on the soil sampled (Albic Luvisol) from a two-factor field experiment: the first factor was nitrogen fertilization (0, 40 and 80 kg ha⁻¹), the second one – variants of foliar and soil application of microelements and selenium. Soil was sampled from a depth of 0–30 cm at the beginning and the end of the growing season. Sampling 1 was after the start of spring vegetation, sampling 2 – after harvesting the crop from the field. Winter spelt (cv. Rokosz) was grown on the experimental plots, with winter rapeseed as the forecrop. In the soil samples the following were assayed: total organic carbon (TOC), total nitrogen (TN) with the Vario Max CNS analyser provided by Elementar and dissolved organic carbon (DOC). DOC was extracted with 0.004 M CaCl₂ and was assayed and using the Multi N/C 3100 Analityk Jena analyser. In the soil samples analysed TOC, irrespective of the sampling date and the microelements application method, ranged from 8.38 to 10.60 g kg⁻¹. In general, the application of microelements into soil in combination with selenium resulted in an increase in TOC in the soil sampled at the end of the vegetation period as compared with the soil sampled at the beginning of it. Irrespective of the application method, there has been identified no effect of fertilization with nitrogen and microelements on total nitrogen and dissolved organic carbon in soil, which is important in terms of the stability and equilibrium of the soil system investigated.