Agriculture Reference
In-Depth Information
Mineral mulch materials were studied at the following proportions: 4 t/ha, 8 t/ha and 16 t/ha;
peat 20 t/ha, 40 t/ha and 80 t/ha; straw 5 t/ha and 10 t/ha. We studied the effect of the
mulch materials both in the pure form and in the form of binary mixtures.
The mulches were studied in the crop rotation. Experiment 1: annual grasses, winter rye,
barley, oats, vetch-oats mixture.
Experiment 2:
annual grasses, barley oats. Experiment 3:
barley.
All mulches were applied to the soil surface once at the beginning of the observation
period (in May) and mixed with the soil layer of 0-5 cm by medium disc harrows. The only
exceptions were the variations with straw in Experiment 1, when straw was applied twice at
the beginning of the first and the fourth growing seasons. After the mulches were applied,
only subsurface tillage was used to preserve their integrity.
As a result of this work, a candidate dissertation (Lednev, 1997) was defended in 1997
and a new method of applying ameliorants and fertilizers was developed (Patent 2164060
RUC2). Certain elements of this technology were used in further research when conducting
different field experiments.
The study found that, in the majority of cases, low and average proportions of the
mulches (bentonite clay 8 t/ha, limestone flour 4 t/ha, peat 40 t/ha, straw 5 t/ha) were
most cost-effective. Increase in yield due to the application of a larger proportion does not
repay the incurred costs. The effect of plain (single) mulches was similar to the effect of
binary mixtures, but their application did not need the additional action of mixing the
ameliorants. Therefore this paper will only discuss the data for plain mulches applied at their
optimal proportion (i. e. bringing the greatest economic benefit).
For convenience, most of the factual data below are presented in the form of graphs. It
should be noted that for all graphs there are summary data of the three field experiments
given for different plots and years, which significantly increases the objectivity of the
findings. To be able to compare the results for different plots, the deviation from the control
(without ameliorants) was calculated in each experiment, and only then the arithmetic mean
of the three experiments was calculated.
1. Effect
of Mulches on Physical and-Chemical Properties of the Soil
One of the main negative features of podzolic soils is their high acidity and low content
of bases in the soil adsorption complex. Mixing the ameliorants and the fertilizers under study
with the soil layer of 0-5 cm had a positive impact not only on the top of the plow horizon,
but also on its entire depth (Figures 1, 2, 3). Limestone powder, as expected, exerted the
greatest influence on the physical and chemical properties. All through the observation
period, it decreased both the exchange and hydrolytic acidity of the plow horizon (by the
average of 16.7% and 21.8% respectively throughout the observation period) and increased
the amount of exchangeable bases (by the average of 23.5%) compared to the control without
mulch. This effect of liming the soil is well known and is based on the neutralization of
mineral and organic acids and the displacement of hydrogen and aluminum ions from the soil
adsorption complex. What is important in our study is that the shallow application of
limestone powder did not decrease its effectiveness, compared with the traditional method of
applying, but reduced the cost of liming.
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