Effect of the Wildfires on Sandy Podzol Soils of Nadym Region, Yamalo-Nenets Autonomous District, Russia

Active land disturbance of soil and environments appears even in remote landscapes of tundra and forest tundra. Wildfires become a frequent factor of soil degradation and intensification of permafrost degradation, also affecting the global balance of carbon, especially content and distribution of polycyclic aromatic compounds. Mature unaffected by fire sandy-textured podzols soils were investigated in comparison with the same soil strongly affected by surface fire in the end of August 2016 in surroundings of the Pangody settlement, Nadym district, Yamal region. Data obtained showed an intensive morphological transformation of the topsoil layers, decreasing total organic matter and apparently increasing the humus enrichment by nitrogen. Wildfires also result in complete transformation of the fractional composition of the polycyclic aromatic compounds. The sum of PAHs increases intensively as well as benzo(a)pyrene content in soils. Therefore, soils of the cryolithozone become more faced to the wildfires during the last decades. Even one-time fire effect results in serious transformation of soil geochemical state.

The effects of organic and inorganic phosphorus amendments on the biochemical attributes and active microbial population of agriculture podzols following silage corn cultivation in boreal climate

Phosphorus (P) is the second most important macronutrient that limits the plant growth, development and productivity. Inorganic P fertilization in podzol soils predominantly bound with aluminum and iron, thereby reducing its availability to crop plants. Dairy manure (DM) amendment to agricultural soils can improve physiochemical properties, nutrient cycling through enhanced enzyme and soil microbial activities leading to improved P bioavailability to crops. We hypothesized that DM amendment in podzol soil will improve biochemical attributes and microbial community and abundance in silage corn cropping system under boreal climate. We evaluated the effects of organic and inorganic P amendments on soil biochemical attributes and abundance in podzol soil under boreal climate. Additionally, biochemical attributes and microbial population and abundance under short-term silage corn monocropping system was also investigated. Experimental treatments were [P0 (control); P1: DM with high P2O5; P2: DM with low P2O5; P3: inorganic P and five silage-corn genotypes (Fusion RR, Yukon R, A4177G3RIB, DKC 23-17RIB and DKC 26-28RIB) were laid out in a randomized complete block design in factorial settings with three replications. Results showed that P1 treatment increased acid phosphatase (AP-ase) activity (29% and 44%), and soil available P (SAP) (60% and 39%) compared to control treatment, during 2016 and 2017, respectively. Additionally, P1 treatments significantly increased total bacterial phospholipids fatty acids (ΣB-PLFA), total phospholipids fatty acids (ΣPLFA), fungi, and eukaryotes compared to control and inorganic P. Yukon R and DKC 26-28RIB genotypes exhibited higher total bacterial PLFA, fungi, and total PLFA in their rhizospheres compared to the other genotypes. Redundancy analyses showed promising association between P1 and P2 amendment, biochemical attributes and active microbial population and Yukon R and DKC 26-28RIB genotypes. Pearson correlation also demonstrated significant and positive correlation between AP-ase, SAP and gram negative bacteria (G−), fungi, ΣB-PLFA, and total PLFA. Study results demonstrated that P1 treatment enhanced biochemical attributes, active microbial community composition and abundance and forage production of silage corn. Results further demonstrated higher active microbial population and abundance in rhizosphere of Yukon R and DKC 26-28RIB genotypes. Therefore, we argue that dairy manure amendment with high P2O5 in podzol soils could be a sustainable nutrient source to enhance soil quality, health and forage production of silage corn. Yukon R and DKC 26-28RIB genotypes showed superior agronomic performance, therefore, could be good fit under boreal climatic conditions.

New associations of the class Molinio-Arrhenatheretea in the in Southern Nechernozemie region of Russia

3 new associations, distributed in the Southern Nechernozemie of Russia, are described for the first time with use of the Braun-Blanquet approach: Poo angustifoliae–Arrhenatheretum elatioris, Festuco pratensis–Leucanthemetum vulgaris, Trifolio ar­ven­si–Rumicetum thyrsiflori. The synecological amplitudes of humidity, acidity and soil richness by mineral nitrogen of the associations are defined. Communities of ass. Poo angustifoliae–Arrhenatheretum elatioris are distributed on the flat slopes of ravines on the dry, subacidic, grey wood loamy soils moderately rich by mineral nitrogen. Communities of ass. Festuco pratensis–Leucanthemetum vulgaris are distributed on fresh, subacidic, rather poor in mineral nitrogen grey and dark grey wood loamy soils on the fallow lands of various age within landscapes of loess plateau; on sod-podzolic loamy, sandy and subsandy soils within landscapes of fluvioglacial loamy and moraine-outwash plains. They can meet occasionally on grey wood loamy soils. Communities of the Potentilla argentea var. are distributed on grey and dark grey wood loamy soils on the fallow lands within landscapes of loess plateau. Communities of the Medicago lupulina var. are distributed on sod-podzolic loamy, sandy and subsandy subacidic, rather poor in mineral nitrogen soils on the fallow lands of various age. They may occur in the small sites on the continental meadows or along highways. Occasionally these plant communities can be found on grey wood loamy soils. Communities of ass. Trifolio arvensi–Rumicetum thyrsiflori are distributed on raised sites on gentle-wavy outwash or moraine-outwash plains on dry and moderately sour, poor by mineral nitrogen easily sandy and sandy podzol soils. For the estimation of a homotoneity of established syntaxa the index of homotoneity of H.Passarge (1979) is used. The ass. Poo angustifoliae–Arrhenatheretum elatioris is characteristic by the high homogenetic variability. Totally, association’s index of homotoneity is high — 0.52. The low index of a homotoneity is characteristic for аss. Festuco pratensis–Leucanthemetum vulgaris — 0.35, for the Potentilla argentea var. — 0.33 and Medicago lupulina var. — 0.44. Following associations have a low index of the homotoneity: аss. Trifolio arvensi–Rumicetum thyrsiflori — 0.33, as in subass. T.a.–R.th. typicum— 0.33, and in subass. T.a.–R.th. helichrysetosum arenarii — 0.44. Such low indexes of a homotoneity are characteristic for semiruderal and serial commu­nities.