NON-TRADITIONAL AMELIORANTS - Fertilizers: Components, Uses in Agriculture and Environmental Impacts - page 203

The data in Figure 1 show that the bentonite clay shaft increases the total exchangeable
bases from 1-2% to 28%, the positive effect was maintained throughout the five years of
observation, and on average with all terms of definitions it was 7.5%. It should be noted that
in this and subsequent diagrams summarizes data from three field experiments which are on
different areas and in different years carried out that significantly increases objectivity results.
In order to be able to compare the results from different sections, on each experiment was
calculated deviation from the control (variant without entering ameliorants), and only then
was found the arithmetic mean of three experiments. A similar, but less significant increase in
the total exchangeable bases observed by other authors (Lgotski, 1979; Sharafeeva, 1980).
Lesser effect of bentonite clays these authors explained by stirring ameliorant with all
arable horizon, resulting to superfluous dilution of its active substance and thus reduce
efficiency. Thus, according to our studies, stirring 8 t-/ha -1 of bentonite clay with a layer soil 0-
20 cm has decreased the total exchangeable bases to 1.2-2.0 mmo-100 g -1 , compared with the
variant where it was stirred with a layer 0-5 cm. In order to achieve the result obtained when
creating a mulch layer, application rate of this ameliorant should be increased to 50-100 t-ha -1 .
Stirring 8 t-ha -1 of bentonite clay with a soil layer of 0-5 cm somewhat reduced the soil
acidity. His influence on this indicator does not always proved statistically, though the
average for five years of observation, there was an increase pH KCl by 2.1% (Figure 2) and a
decrease of hydrolytic acidity by 5.4% (Figure 3) as compared with control without mulch
material. Reducing the soil acidity is explained by faintly alkaline reaction of this ameliorant
(pH KCl - 6.4) and very high base saturation.
Similar results the interaction of bentonite clay with soils that have an acid reaction were
obtained by other researchers (Lgotski, 1979; Sharafeeva, 1980).
Figure 2. Effect of bentonite clay ploughed in the 0-5 cm soil layer on exchange acidity of the arable
layer, % deviations from control (no ameliorant).