Assessing the humus status and CO2 production in Soils of natural and agrogenic landscapes under global change
Lyudmila N. Purtova
1Federal Scientific Center of the East Asia Terrestrial Biodiversity FEB RAS, Vladivostok, 690022, Russia
The humus status and CO2 production have been assessed in soils of natural and anthropogenic landscapes in southern regions of the Far East. A higher production of CO2 is typical of burozems and soddy-eluvial-metamorphic soils. These are soils with medium or high humus content, high potential humification capacity, and medium enrichment with catalase. A decrease in the content of humus in the plow horizons of soils in agrogenic landscapes is revealed compared to their natural analogues. The studied soils have humus of the fulvate–humate type. The fractions strongly bound to the mineral soil component prevail in humic acids. In waterlogged mucky-humus gley soils, the anaerobic conditions hamper the biological activity and transformation of organic matter, which favors its accumulation. A low production of CO2 is observed in soils with reducing conditions. In soils of agrogenic landscapes (agro-dark-humus podbels and agro-dark-humus gley soils), the content of humus and the production of CO2 decreased because of the removal of organic matter of plant origin at the agricultural use of soils and the lack of fresh organic matter. A low potential humification capacity (0.07) was revealed in agro-dark-humus podbels. This was largely favored by the increase in the number of bacteria and actinomycetes, which enhance the mineralization of humus, and the predominance of FA fractions in humus. The catalase activity in soils increased because of their high biogeneity, and the production of CO2 remained low. This is related to the periodical overmoistening of soil surface and the low content of organic matter.To determine the differences between the CO2 emission parameters in soils of agrogenic and natural landscapes under global change, monitoring studies should be extended.