Transformation of the humus composition in light-textured soddy-podzolic soils as affected by increasing lime doses and in the postagrogenic period

The fractional-group composition of humus in a loamy-sandy soddy-podzolic soil limed using different doses of chalk was studied. The transformation of the humus composition is related to the dose of the lime fertilizer and terminates after the complete dissolution of the ameliorant applied. The full dissolution of the chalk applied in high doses ends within three years after the liming. The humus composition of the cultivated sandy soddy-podzolic soil was investigated at different stages of the postagrogenic successions. The changes in the humus composition due to the neutralization of the soil’s acidity and cultivation are rather stable in time. Sixty years after the termination of the anthropogenic impact, in the humus composition of the sandy soddy-podzolic soil, humic acids bound with calcium were found. One hundred years after the end of the soil cultivation, its humus composition approaches the humus composition of the virgin soil. However, no complete restoration of the humus composition has occurred. Data on the optical density of the humic acids are presented.