Factors controlling dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and DOC/DON ratio in arable soils based on a dataset from Hungary

Dissolved organic matter (DOM) is believed to play an important role in soil processes and in the N, S and P supplies to plants in all types of soils, but most research has focused on forest soils. This study aimed to assess the effect of soil factors and soil parameters on DOC, DON and DOC/DON ratio of 190 arable soils from Hungary. The soil samples are representative of the agricultural soils of Hungary. To quantify the dynamics of DOC, DON and the DOC/DON ratio, as affected by 14 soil parameters, multiple linear regression was performed using (i) factor scores extracted by principal component analysis and (ii) the soil parameters. The results of PCR revealed that the soil factor N status had a major influence on the DOC concentration in the soil and also on the ratio of DOC to DON, but no relationship was found for DON. The soil texture factor made a great contribution to both DOC and DON, whilst the soil acidity factor had a positive effect on DOC and a negative effect on DON. When regression was performed for the soil parameters, soil organic matter and CEC were found to make the greatest contribution to DOC and DON. Other variables, such as the dissolved inorganic nitrogen, CaCO3 and EC of the soils, were also found to be decisive parameters.

Research highlights
► Soil factor “N status” had a major influence on the DOC, but no relationship was found for DON.
► “Soil texture” factor made a great contribution to both DOC and DON.
► “Soil acidity” factor had a positive effect on DOC and a negative effect on DON.
► Soil organic matter and CEC were found to make the greatest contribution to DOC and DON.