A considerable proportion of the soil’s carbon and nitrogen content can be found in the form of organic materials. But, by evaluating the nutrient supply of plants, the directly available inorganic nutrients are of primary importance. As a result of the decomposition and mineralization of different organic compounds, nutrients become available for the plants. The amount of carbon and nitrogen forms in the soils changes considerably during the decomposition of organic compounds. The transformation of the two elements is closely related, since the decomposition of organic materials has a significant effect on both. To get a better knowledge on the nutrient supply of the different soils, the amount of some carbon and nitrogen forms were examined in 12 extremely different soil types collected from different sites of eastern part of Hungary. The analysis of the soils’ carbon content and the amount of specific carbon forms is necessary because the transformation of carbon compounds is related to the nitrogen cycle, which has primary importance in the nutrient supply of plants. That is why we have to measure the different forms of carbon and nitrogen in soils. The total carbon and total nitrogen content of the soils examined was measured by an ELEMENTAR VARIO EL CNS analyser (Hanau, FRG). The organic carbon content was measured according to Tyurin with destruction method. The amounts of organic compounds, which potentially can be easily decomposed, and two of the most important nitrogen containing ions were measured also after an extraction by 0.01 M/dm 3 CaCl 2 solution. After our research hypothesis they may correspond to the part of the total amount of organic compounds which potentially easily mineralise. Therefore, they may play an important role in the available nutrient supply of the different soil types as well as in plant nutrition.

carbon and nitrogen forms of soils, plant nutrition

Presentation: oral