Organic matter transformation in post-agrogenic soils of the Middle Taiga zone

Objective. The purpose is to study the organic matter transformation in Podzols from the middle taiga zone.

Methods. The study materials are arable lands from the central regions of the Komi Republic. These lands are not agriculturally used since the early 90-ies of the former century. The soil analyses are done according to the common methods.

Results. The study allows for the humus profile structure of Podzols along with the following successive stages as meadow idle land young forest dwarf shrub-green moss spruce forest. It also describes the mechanisms of post-agrogenic humus transformation in agricultural sod Podzols due to the self­ restoring succession.

Conclusion. Initially, the post-agrogenic soils normally repeat agrozems by characteristics. The upper soil part forms a thin grey-humus (sod) horizon. It contains large amounts of humus, exchangeable cations, and nutrition elements. The specific synthesis and destruction processes of humic substances at the meadow idle land stage change the qualitative humus composition. In contrast with arable lands, the humus composition is dominated with fulvic acids as being best appropriate to the concerned bioclimatic zone. The humuc-fulvic humus composition holds only in the upper old-arable soil part of the meadow idle land. The appearance of pioneer tree species increases the dominating position of FAs and the Cha/Cfa ratio resembles that for forest soil. The organic matter is poor in nitrogen compounds, especially at the young forest stage. By the C/N ratio, the post-agrogenic soils also gradually get close to naturally formed soils under virgin forest.

1. Atlas of soils of the Komi Republic / G.V. Dobrovolsky (Ed.) Syktyvkar: Komi Republican printing house, 2010. 356 p.

2. El’kina G.Ya. Optimization of mineral nutrition of plants on podzolic soils. Ekaterinburg: UrB RAS, 2008. 280 p.

3. Erokhova A.A., Makarov M.I., Morgun E.G., Ryzhova IM . Change in the composition of organic matter of sod-podzolic soils as a result of natural restoration of forest on arable land // Soil science, 2014, No. 11. P. 1308-1314.

4. Kechaykina I.O., Ryumin A.G., Chukov S.N. Postagrogenic transformation of organic matter of sod-podzolic soils// Soil science, 2011, No. 10. P. 1178-1192.

5. KurganovaI.N., Ermolaev А.М., Lopez de Gerenyu V.O., Larionova A.A. et al. Carbon flows and pools in the fallow lands of the Moscow region // Soil processes and spatial-temporal organization of soils: Collection of scientific papers / V.N. Kudeyarov (Ed.) Moscow: Nauka. 2006. P. 271-284.

6. Litvinovich A.V., Pavlova О.Yu., Chernov D.V. Change of humus state of sod-podzolic soil at the termination of anthropogenic impact // Reports of the Russian Academy of Agricultural Sciences. 2002. No. 6. P. 26-28.

7. Lyuri D.I., Goryachkin S. V., Karavaeva N.A., Denisenko Е.А. et al. Dynamics of agricultural lands of Russia in the XX century and postagrogenic restoration of vegetation and soils. Moscow: GEOS, 2010. 426 p.

8. Orlov D.S. Humus acids of soils and the general theory of humification. Moscow: Moscow State University, 1990. 325 p.

9. Romanovskaya, A.A. Organic carbon in soils of fallow lands of Russia // Soil science. 2006. No. 1. P. 52-61.

10. Chalaya Т.А., Vladychensky A.S., Telesnina V.M. Dynamics of humus state of soils in postagrogenic landscapes of the southern taiga // Proceedings of the conference "Geography of productivity and biogeochemical cycle of terrestrial landscapes: to the 100th anniversary of Prof. N. I. Bazilevich". Pushchino, 2010, P. 623-626.