Properties of pyrogenic eutrophic peat soil of Tagan mire (south of Tomsk Oblast)

We consider the problem of pyrogenic degradation of peat soils. Studies conducted in Tomsk Oblast on the eutrophic Tagan mire. The mire is located in the ancient hollow runoff between the Ob and Tom rivers, on the second terrace above the floodplain of the Tom River. Studies were carried out on the dried and depleted area of the mire. The initial depth of the peat deposit reached 9.3 m, residual 1-1.4 m. The plot was exposed to fire five years ago. For the study three cuts of different capacity were laid. Soil that we have studied is attributed to pyrogenic modified peat soils. Fire destroyed only its surface horizons. Soils like this retain their fertility after the fire. They can be used in agriculture after simple agronomic or agromeliorative measures. The study of physical, chemical and morphological properties of the pyrogenic peat soils was conducted. In selected samples ash content, moisture content, acidity, content of N-NH ₄, N-NO ₃,K ₂O, P ₂O ₅, F ₂O ₃ were determined. It was revealed that the pyrogenic horizons have changed in the full range of properties (morphological structure, physical and chemical properties). After the pyrogenic impact changes of physical and chemical properties were observed. Ash content, content of N-NH ₄, N-NO ₃,K ₂O, P ₂O ₅, F ₂O ₃ increased. The most significant changes occur in the upper soil horizons. Ash content of the pyrogenic soil increased from 7.25 to 83.25 %. The acidity of the soil after the fires increased from 6.0 to 7.93 pH units. Soil moisture decreased and mechanical shrinkage has occurred. As a result, the reservoir temperature increased, the aeration profile decreased. Reducing conditions changed to oxidizing conditions. The biological activity of the soil increased. The process of ammonification and nitrification in the peat deposit increased. Therefore, the content of ammonium and nitrate nitrogen in the soil sections increased. The high values of iron oxide content in the upper soil layers (up to 292 mg / 100 g dry soil) were caused by its concentrating in the fire. Phosphorus oxide in the upper horizons also has higher values up to 779.33 mg / 100 g of dry soil. The high content of phosphorus and iron in the peat deposit of cuts is explained by the vivianite nature of the rocks. K ₂O content in these soils changed from 1.16 to 46.39 mg / 100 g dry soil. The increase of fertile elements is an argument in favor of the agricultural use of the Tagan mire soil. But the mire is located in the suburban area of the city of Tomsk. The mire is a regulator of the water regime of watercourses; it contributes to the maintenance of a stable level of groundwater. To improve the environmental situation of the surrounding area it is suggested to recultivate the pyrogenic portion of Tagan mire and then use the plot of the mire for afforestation.

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