Agriculture Reference
In-Depth Information
diate impact on soil chemical composition because of having infl uence on transition of
chemical elements from immobile forms to mobile forms.
Soil moisture regime for certain period was determined according to GOST 28268-
89 during vegetation (May, June, July, August, and September). Moisture content in
the soil (39.4%) was suffi cient and favorable for summer wheat seed germination and
sprout formation in June 2011. Soil moisture was low in 2009 and 2010 (11.7 and
13.6% respectively), which was refl ected by fi eld germination rate and biological re-
sistance of plants. The important period in water consumption is thought to be booting
and ear formation stage, that is, period of reproductive organ formation, which comes
to be in July in our research. Maximally hard conditions for wheat were observed in
July 2010, which was characterized by precipitation defi ciency on the background of
increased air temperatures. Soil moisture during this period was no higher than 6.8
percent. Low soil moisture (9.0%) was observed in August 2011, when milk stage of
grains took course and plants consumed 20-30 percent of all moisture during vegeta-
tion period. Warmth and water regime infl uenced the soil chemical properties, the de-
gree of mobility of different elements, and the plant's ability to consume them through
its root system.
Soil acidity is stated by the negative logarithm of the hydrogen ion concentration
pH. This characteristic determines the availability of chemical elements for plant or-
ganism. It is worth mentioning that amelioration of sod-podzolic soils leads to changes
in the qualitative composition of organic matter, decrease of fulvic acids composition,
and increase of lime humates. At the same time, as a result of amelioration, the base
exchange capacity increases and composition of exchangeable cations changes: in-
creasing of consumed Ca
++
and Mg
++
and decreasing of exchange Н
+
and Al
+++
.
Reaction of soil solution markedly changes because of saturation of soil by Ca
++
and Mg
++
cations: pronounced acidity, which is characteristic to virgin soils, gradually
replaced by subacidic and sometimes neutral and weakly alkaline reaction. Biologi-
cal activity of soil microbial fl ora—nitrate bacteria and azotobacter—which does not
occur in virgin soils and weakly cultivated soils or occurs in very fractional amount,
intensifi es because of it [11].
8.2 MATERIAL AND METHODOLOGY
S
oil of the experimental plot belongs to weakly alkaline type and has medium pH 7.70.
It is known that nutrients and chemical elements for wheat plants will be available un-
der a pH range 6.0-7.5. If pH level is lower, key nutrients will be either less available
or become toxic for plants. Therefore, soil pH of experimental plot can be referred as
satisfying to requirements of the culture.
Dry residue (solid residue) is a characteristic of soil salinity; it is determined by
the ratio of anions and cations in the soil solution. In normal conditions, it cannot
exceed 0.30 percent; in soil samples, it is equal to 0.35 percent. Salinity is determined
by salt content in soil solution. Salts need to be formed mostly by sodium, calcium,
and magnesium cations with chloric and sulfuric anions. Potash cations, bicarbonate,
carbonate, and nitrate anions can comprise the insignifi cant part. Thus, results by dry
residue in soil, which were obtained in this experiment, allow drawing a conclusion
that anion and cation amounts are optimal and they are the main compounds of the soil
in current agroclimatic conditions.
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