Changes in the nitrogen status of grey forest coarse dusty light loam soil under different systems of fertilisation and chemical amelioration

Abstract

This paper presents the results of research in a stationary experiment, launched in 1992 on grey forest coarse-dusty light loamy soil, aimed at studying the influence of long-term chemical amelioration and various fertilisation systems (mineral, organic, organic-mineral) on the nitrogen regime. Nitrogen is extremely important in agriculture, as all growth processes, photosynthesis, metabolism, and yield volume and quality eventually depend on this element. In Ukraine, the share of soils of woodland composition in total soil cover exceeds 33%, while the share of agricultural land is 25%. Since the humus content and its total reserves are an integral measure of soil formation and a key characteristic that determines the overall habitat of the soil, the article analyses changes in humus content as a response to the above factors. It has been found that the gross nitrogen content reflects the humus content, fully depends on and varies with the humus content of the latter. There is a high correlation between these indicators for all variants of the experiment (r = 0.991). The data obtained indicate that only with the use of green manure and by-products of the predecessor and moderate doses of mineral fertilisers in combination with liming, there is a moderate increase in total nitrogen as compared to the initial level. The rise amounted to 0.36 – 0.45 t/ha and in this case, it is possible to observe its extended reproduction. Only after mineralisation does the nitrogen of organic compounds become available to plants. The easily hydrolysed form of nitrogen is a fairly reliable indicator of whether the plants are supplied with this element. According to the classification, the soil under study, with a mobile compound content of 81.2 – 103 mg/kg, falls into the group of soils with a very low degree of nutrient supply, but the degree of hydrolysis of organic matter in it is high (9.6 – 10.2%). With the combined use of green manure, non-commodity crop products, and one-dose mineral fertilisers along with lime, this form of nitrogen increased by 27.5% compared to the control. Under the above fertiliser complex, there was an increase of 16.5 mg/kg in the amount of N-N03-+N-NH4+ compared to the control, plus 7.4 mg/kg of soil nitrification capacity