PREFERENTIAL WATER FLOW, LOCAL SOIL BIOTA AND STRUCTURE DEGRADATION IN
CHERNOZEM 20 YEARS AFTER LAND-RECLAMATION
E.V. Shein, A.B. Umarova, E.Yu Milanovskiy, I.V.Sokolova
Moscow State University, Faculty of Soil Science, Moscow 119992, Russia; e-mail:
e.v.shein@gmail.com
Soil land reclamation constructions were created near 20 years ago in the open-cast ore mining
and have been in agricultural use since that time. Land reclamation consisted in creating 60-cm soil
Chernozem layer above the thick sand layer. Dramatic changes occurred in soil structure of the
Chernozem layer due to agricultural practice. Typical soil granular aggregates of size 1–5 mm
transformed into a prismatic coarse 50-mm peds with flat or rounded surface and columnar 100-mm
vertically oriented blocks at the depths of 20–40 and 40–60 cm. Study of the soil water regime showed
formation of temporary perched water above the sandy layer during intensive spring and summer
rainfalls. Field starch tracer experiments revealed an existence of preferential water pathways through
the Chernozem layer. The vertical preferential flow occurred along the block surface downward,
saturated the blocks and create favorable conditions for the soil gleization inside the ped, anaerobic
microbiota formation (Clostridium limosum, Cl.supterminal and others) (Fig. 1b); after period of the
preferential flow functioning the period of ped draining begun and aerobic microbiota (Rhodococcus
terrae) was developed on the surface of the ped (Fig. 1a).
a)
Clostridium
propionicum
9%
Butyrivibrio
7S-14-3
4%
Ochrobactrum sp.
Rhodococcus terrae
23%
Rhodococcus equi
5%
Anaerobic
*
Aerobic*
b)
Ruminococcus sp. Methylococcus sp.
FeRed 5%
19%
Clostridium 1%
limosum/Cl.supter
minal
Methylococcus sp.
23%
39%
Clostridium
propionicum
4%
Butyrivibrio Butyrivibrio
1-4-11
7S-14-3
3%
6%
Rhodococcus
terrae
18%
Fig. 1. Microbiological composition on the ped surface (a) and in the inner part of the ped (b) from the
depth 40–60 cm of the Chernozem layer of the soil construction
* - in the group “Anaerobic” the obligate and facultative anaerobes were included, but in “Aerobic”
group the obligate microorganisms and microaerofiles were included.
This microbiological composition favored the Fe-ions migration to the surface, transformation to Feoxides films on the ped surface and columnar rigid blocks formation. Results of the study assume that
the preferential flows create favorable conditions for the soil gleization inside the ped, anaerobic
microbiota formation, but during following dry periods aerobic microbiota on the surface ped layers
transform Fe2+ to Fe3+ and lead to aggregate transformation from granular structure to the columnar
blocks. Results of the data evaluation will be discussed.
Keywords: soil structure, preferential flow, aerobic and anaerobic microbiota