Total organic c and its decomposable part in arable soils in the Czech Republic

Abstract

Total soil organic matter and its decomposable part have been studied in arable farm fields in the Czech Republic. One hundred and forty localities have been selected. Besides the soil types and subtypes (taxonomical soil units), textural units, total organic carbon content, and even geographical distribution was taken into account. Soil samples have been taken from the top soil (0 – 20 cm) at the selected sites and a number of analyses were carried out. Organic C content in the top soil from the selected 140 sites on arable soils ranged between 1% and 2% in more than 80% of the soil samples. C/N ratio oscillated around 10 in a rather narrow band. There were no remarkable changes in the organic C content in the top soil in 82 sites over the last decade (1992 to 2002). The distribution of the organic C content in the soil samples according to the taxonomical soil units have shown the lowest values in the Haplic Luvisols and Albeluvisols. Their variability was relatively low. In Cambisols, on the contrary, the average C content values were higher but their variability was also much higher than in Luvisols. The decomposable organic C content closely correlated with the total organic C content. The lowest decomposable C contents were found in the soil samples from Luvisols, probably due to the favourable conditions for microbial activities and organic matter turnover. Hot water soluble C accounted for about 3 – 4% of the total organic C content and, apparently, its content increases with the increasing total organic C content. There were highly significant correlation coefficients between most of the selected criteria.

Keywords:

• Soil organic matter
• Decomposable soil organic matter
• Organic carbon
• Hot water soluble carbon
• Inert organic carbon

Acknowledgement

This work was funded by the Ministry of Agriculture Czech Republic project No QD 1329.