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ABSTRACT
ALVES JUNIOR, Jainir. Nitrogen fertilization in bean cv. BRS-MG Talismã
under a no-tillage and a conventional tillage crop management systems.
2007. 61 p. Dissertation (Master in Agronomy/Crop Science)-Universidade
Federal de Lavras, Lavras, MG.
*
Nitrogen is the largely required nutrient by bean plants and thus, to reach high
yields, corresponding amounts of N fertilization are needed, which makes the
nutrient indispensable. The objective of this work was to evaluate in the field
responses of bean cv. BRS-MG Talismã to increasing nitrogen rates applied at
sowing and later as topdressing. To study sowing nitrogen fertilization, a total of
seven experiments were carried out under conventional tillage and no-tillage
crop management systems, in 2002 and 2003 harvest seasons. The experimental
design was in a randomized block with five replicates and six treatments (0, 30,
60, 90, 120 and 150 kg.ha
-1
of N, using urea as the nutrient source) used in a
single application at sowing. To study topdressing nitrogen fertilization four
experiments were carried out in the field in Madre de Deus de Minas and São
Vicente de Minas. In dry season 2004, the used experimental design was in
randomized blocks, with ten replicates and five topdressing N rates, applied at
20 DAE (0, 30, 60, 90 and 130 kg ha
-1
). In the further assays the same
experimental design was used with six replicated and 4 N rates as topdressing (0,
40, 80 and 120 kg ha
-1
). To study the interaction nitrogen fertilization vs
topdressing two experiments were carried out (no-tillage and conventional
tillage), at the 2004/05 raining season. The experimental design was in
randomized blocks with three replicates in a factorial scheme 4x4 encompassing
4 N rates at sowing (0, 40, 80 and 120 kg.ha
-1
) and 4 topdressing N rates (0, 40,
80 e 120 kg.ha
-1
) at 20 DAE. Each plot was composed by four 5m-long rows,
0.5m apart from each other and a 16 seed.m
-1
density was used. From the first
group of experiments, results showed that in environment more adequate to bean
crop, such as irrigated winter season, the increase in N rate at sowing enhance
the number of pods per plant and therefore bean grain yield, until a maximum
point, of approximately 57 kg.ha
-1
of N. From this point onward, there is a
continuous reduction in plant population because of the saline effect caused by
nitrogen fertilizers, which also reduced crop production, limiting the possibility
of using a high N rate at sowing. Under excessive rainfall, such as the raining
season, or any other limiting factor, increasing N rates at sowing had less effect
on final plant stand and bean grain yield. For the second group of experiments,
*
Guidance comittee: Messias José Bastos de Andrade – UFLA (Advisor), Janice
Guedes de Carvalho – UFLA e Augusto Ramalho de Morais – UFLA.