Disponibilidade hídrica no solo e intervalo após a calagem para implantação de gramíneas forrageiras
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Data
2021-02-26
Autores
Gregório, Francisco Cidnei
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Universidade Federal de Mato Grosso
Resumo
In tropical conditions, the correction of soil acidity is an important
step in the process of implanting forages, being essential for success in the
pasture formation. However, the need for intervals between application of lime
and sowing of more than 60 days occupy a considerable part of rainy season and
can compromise the establishment pasture. Although it involves time, the
reaction of the limestone in the soil is dependent on the soil water availability, and
the faster the greater the presence of water interacting with the CaCO3 of the
limestone. In this work, the objective was: (1) to verify if it is possible for acidity
correction to occur in less than 60 days after the incorporation of limestone; (2)
what soil water availability is necessary for acidity correction to occur in less than
60 days. For this, two experiments were carried out in a greenhouse in
Rondonópolis-MT with a completely randomized design in a factorial scheme. In
the first experiment, 8 treatments were evaluated, obtained from the combination
of the number of times the soil was raised to the maximum water retention
capacity (1, 2, 3 and 9 irrigations) and two expected base saturations (50 and 60
%). Dolomitic lime (calcium oxide: 31%, magnesium oxide: 21%, neutralizing
power: 107%, RE: 80.4% and total relative neutralizing power: 86%) was used to
raise base saturation. The pH and aluminum saturation of the soil, before liming,
were 4.1 and 75%, respectively. Forty-five days after the incorporation of the lime,
chemical analysis of the soil was carried out and sowing of the cultivar BRS
RB331 Ipyporã (Brachiaria brizantha x Brachiaria ruziziensis). The soil pH
(CaCl2) was raised to values above 5.0 in all treatments. Irrigations number did
not affect the saturation of toxic aluminum in the soil, however, there was a
reduction in aluminum saturation from 75.0 to 3.5%. Beside, irrigations number
did not alter the development of the grass and a single irrigation, increasing the
soil moisture for maximum water retention capacity, corrected the acidity of the
soil and made it possible to reduce the interval between liming and sowing to 45
days. Second experiment was carried out with the cultivar Mombasa (Panicum
maximum), in which 6 treatments were adopted in a 3x2 factorial scheme,
constituted by the combination of three soil water availability (50, 75 and 100%
of the maximum water retention capacity in the soil) and two lime reaction periods
(30 and 60 days). Soil water availability changed the lime reaction time. Results
of the soil analysis indicated that thirty days after liming, with a precipitation
capable of raising the soil moisture to 50% of the maximum water holding
capacity, chemical changes occurred in the soil, so that the main one was the
absence of toxic aluminum. However, for implantation of the pasture 30 days after
liming, it is necessary a precipitation that provides the elevation of the soil
moisture to 75% of the maximum soil water retention capacity.
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GREGÓRIO, Francisco Cidnei. Disponibilidade hídrica no solo e intervalo após a calagem para implantação de gramíneas forrageiras. 2021. 28 f. Dissertação (Mestrado em Zootecnia) - Universidade Federal de Mato Grosso, Campus Universitário de Rondonópolis, Instituto de Ciências Agrárias e Tecnológicas, Rondonópolis, 2021.