Changes in Organic Carbon in Mineral Topsoil of a Formerly Cultivated Arenosol under Different Land Uses in Lithuania

Abstract

This study aims to determine the differences in the organic carbon, humic acid (HA), and fulvic acid (FA) concentrations in the A and AB horizons, depending on land use, in order to determine the influence of the land use on the soil organic carbon (SOC) sequestration rate in the A horizon, and to assess the impact of the land use on the quality of the humic substances (HS) (the humification rate (HR) and the HA/FA ratio). On the basis of the data of 1995–2018, it would be expedient to convert cropland (CL) areas to fertilized managed grassland (MGfert) in order to increase the SOC accumulation (28%) in the Arenosol. In the unfertilized managed grassland (MGunfer) areas, the SOC accumulation in the A horizon was similar to that in the MGfert (p > 0.05); however, significantly less (−45.0%) HAs were formed, the HR decreased 2.8%, and the HA/FA ratio was 1.12%. This means that less stable humic substances were formed in the MGunfer soil. In the Arenosol, the fastest SOC sequestration took place in the AL and PP areas, the annual SOC stocks increased by 393 and 504 kg ha−1 year−1, respectively, and the HR increased to 19.1–21.3% (CLfert: 11.9%). However, these types of land use produce more FAs (14.5 and 32.5% more, respectively, compared to the MGfert, and 36.3 and 57.7% more, respectively, compared to the CLfert), which can lead to soil acidification and can accelerate eluvial processes. Because of the faster leaching of the FAs from the upper layers of the A horizon to the AB horizon, the humus type changes from humate–fulvate in the A horizon, to fulvate–humate in the AB horizon.

Effect of Long-Term Different Land Uses on Improving Stable Humic Compounds in Arenosol

“…The carbon-to-nitrogen ratio (C/N) in 1995 ranged from 12.5 to 13.6, and this was favourable for the transformation of the organic matter in the soil. For the long-term experiment, the experimental land use changes and experimental design are described in more detail in [31].…”

Development of an aptasensor for dibutyl phthalate detection and the elucidation of assay inhibition factors

“…In the previous studies regarding the occurrence of humic acids in the environment, the environmentally relevant concentration ranged from ∼0.1 to 1970 mg L −1 . [54][55][56] Therefore, 100 mg L −1 of humic acids is still environmentally relevant concentration and it may act as an inhibition factor of SGaptasensor applications to environmental samples.…”

Exploring the Influence of Natural and Agricultural Land Use Systems on the Different Lability Organic Carbon Compounds in Eutric Endocalcaric Arenosol

“…During the long-term experiment, various biological and agroecological properties were analysed separately [27]. At the beginning of the experiment, the pHKCl of the humus layer ranged from 6.0 to 6.8, SOC was between 9.5 and 9.9 g kg −1 , and there was 157-188 mg P2O5 kg −1 and 170-194 mg K2O kg −1 .…”