Agriculture Reference
In-Depth Information
The stirring of bentonite clay at a dose of 8 t-ha
-1
in the 0-20 cm soil layer also increased
grain yield, the amount of raise ranged from 2.3 to 10.6% of control (without ameliorant).
E
FFECT OF
B
ENTONITE
C
LAY TO
R
EDUCE
THE
M
OBILITY OF
H
EAVY
M
ETALS
IN
C
ONTAMINATED
S
OILS
The unswerving growth of industrial production and population will inevitably lead to an
increase in anthropogenic impacts on the environment and, in particular, on the soil.
A particular danger causes chemical contamination of soil by various pollutants and
primarily heavy metals as they not only reduce soil fertility, but also can accumulate in plants
and then enter the food chain to animals and humans and cause variety diseases.
In the European part of Russia among the most common and dangerous pollutants are
lead and cadmium. The main part of the most contaminated soils located in major industrial
centers and their surroundings, in mineral deposits, along the highways.
Restoration of soil fertility contaminated with heavy metals is impossible without a
specially designed system of actions for reclamation. Chemical, physical, physicochemical
and biological methods are used to carry out this type of work. Each of them has its positive
and negative sides.
Reclamation of soils contaminated with heavy metals, via clay minerals, including
bentonite clay, is based on physicochemical absorption of pollutants by colloidal part of
ameliorants. Consumed by heavy metal ions are less mobile and much less absorbed by plants.
Laboratory experiments showed that bentonite clay showed a statistically significant
effect on the reduction of the mobility of heavy metals only rate of application ≥ 50 t-ha
-1
and
qualitative stirring it with a layer of contaminated soil. Studies in the field experiments have
shown that the application of bentonite clay at 50 t-ha
-1
in arable horizon contaminated sod-
podzolic soils has decreased degree of mobility of lead at 23-42%, cadmium - by 5-21%.
Doze of ameliorant 100 t-ha
-1
reduced degree of mobility of lead at 44-53%, cadmium - by
18-32% (as aextractant used 1 molar solution of calcium chloride).
Recultivation using as ameliorant bentonite clay is especially effective on sandy and
sabulous soils, as it additionally provides a complex positive influence on many agrochemical
and agrophysical properties.
C
ONCLUSION
Bentonite clay is a promising ameliorant, providing a complex positive impact on a
number of agrochemical and agrophysical properties. It performs many functions soil humus
(absorbs and retains water in its composition, mineral nutrients, effectively adheres the soil
particles together, increases the total exchangeable bases, buffer capacity of soil, etc.).
Therefore, it is most clearly shows its positive features on low-humous soils, especially
light granulometric texture.
To reduce the rates of application of bentonite clay (up to 8 t-ha
-1
) while maintaining the
effectiveness we propose stirring it with the soil layer of 0-5 cm.
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