52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Produção de Brachiaria brizanta cv. Xaraés fertilizada com nitrogênio e enxofre1
Daniel da Silva Tavares2, Natalia Guarino Souza Barbosa3, Aline Cristina Richart4, João Cardoso de Souza Junior5,
Mario Lopes da Silva Júnior6, Paulo Campos Christo Fernandes7
2
Parte do trabalho de conclusão de curso do primeiro autor.
Engenheiro Agrônomo. e-mail: [email protected]
3
Professora do Instituto de Saúde e Produção Animal, Universidade Federal Rural da Amazônia. Av. Tancredo Neves, 2501, Belém, CEP 66077
530. e-mail: ([email protected])
4
Discente do Instituto de Ciências Agrárias, UFRA, PA. Bolsista do CNPq/Capes. e-mail: ([email protected]).
5
Engenheiro agrônomo, mestrando do programa de Solos e Nutrição de Plantas, ESALQ- USP. Bolsista CNPq. e-mail: ([email protected])
6
Professor do Instituto de Ciências Agrária, Universidade Federal Rural da Amazônia. Av. Tancredo Neves, 2501, Belém, CEP 66077 530. e-mail:
([email protected])
7
Pesquisador Embrapa Cerrados. BR-020, Planaltina, Distrito Federal, CEP 66077 530. e-mail: ([email protected])
Resumo: A fertilização é fator que tem proporcionado elevada resposta na produtividade e qualidade da forragem e
dentre os nutrientes o nitrogênio (N) e enxofre (S) merecem destaque por suas influências na produção de pastagens.
Objetivou-se avaliar a produção de massa seca das folhas, de colmo + bainha, massa seca da parte aérea e raiz, massa
seca total e relação parte aérea/raiz do capim Xaraés em função de doses de N e S. O experimento foi conduzido em
casa de vegetação no período de agosto/2014 a setembro/2014. Adotou-se esquema fatorial 4x2 em delineamento
experimental blocos ao acaso, com quatro repetições, perfazendo um total 32 unidades experimentais. As doses
foram: de N (0, 50, 100 e 200 mg dm-3) e de S (com e sem S, 0 e 25 mg dm-3). As doses de N foram significativas
para as variáveis estudadas com as maiores respostas na dose próxima de 100 mg N dm-3, ao passo que o S não
influenciou as variáveis estudadas.
Palavras–chave: Amazônia, fertilização nitrogenada, forrageiras, nutrição mineral de plantas
Brachiaria brizanta cv. Xaraes production fertilized with nitrogen and sulfur
Abstract: Fertilization is a factor that has provided high response in productivity and quality of forage. Among the
nutrients nitrogen (N) and sulfur (S) are noteworthy for their influence in the production of pastures. The objective
of this study was to evaluate dry matter production of leaves, stem + sheath, dry matter of shoot and root, total dry
matter and ratio of shoot / root of the Xaraes grass due to N rates and S. The experiment was conducted in a greenhouse
from August / 2014 to September / 2014. The experimental design adopted was the randomized block in a 4x2
factorial scheme with four replications with a total of 32 experimental units. The doses were: N (0, 50, 100 and 200
mg dm-3) and S (with and without S, 0 and 25 mg dm-3). The N doses were significant to the variables, with the
greatest response close to the dose of 100 mg N dm-3, while the S did not influence the variables studied.
Keywords: Amazon, forage crops, mineral nutrition of plants, nitrogen fertilization
Introduction
Brazil is an important producer of meat and milk, with grazing cattle raisings of about 212 million heads,
besides having edaphoclimatic environments with excellent potential to increase its participation into the world
market. To promote the diversification of forage in 2003, Embrapa Beef Cattle launched the B. brizantha cultivate
Xaraes grass. A clump forming plant that has an average height of 1.5 m and can take root at the nodes baseline, with
rapid establishment and regrowth.
The efficient use of mineral fertilizers is the alone factor that mostly contributes to increasing agricultural
productivity. N is one of the mineral elements required in larger quantities by plants and one that most limits growth,
but when correct fertilization is carried out, N is the most responsive nutrient. This high nitrogen response is due to
its active participation in the plant metabolism, being a constituent of proteins, nucleic acids and many other cellular
components, membranes, many phyto hormones and acts in the increase of production in pastures with higher
nutritional values (Malavolta, 2006).
There is a need for studies about forage production for cattle production in low fertility soils of Eastern
Amazonia, due to low biological indices and the growing need for fertilizer use and conservation of natural areas in
these areas. Thus, the objective was to evaluate the dry matter production of grass Xaraes due to the combination of
N and S. doses.
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52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Material e Methods
The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia - UFRA in Belem,
Para, from August to September 2014. It was used randomized blocks experimental design of in a 4x2 factorial
scheme with four replications, with four doses N (0, 50, 100 and 200 mg dm-3) and two doses of sulfur (0 to 25 mg
dm-3). The experimental units were composed by plastic pots containing 5 kg of soil characterized asYellow Latosol,
medium texture collected at 0-20 cm. After preparation of the sample, soil chemical analysis was held presenting the
results: pH (H2O) = 5.15, OM = 21.98 g kg-1, CTC = 9.56 cmolc dm-3, P = 2, 0 mg dm-3, K = 0.13 cmolc dm-3, Ca =
0.73 cmolc dm-3, Mg = 0.55 cmolc dm-3, V = 13%. The recommendation of lime and fertilizers were based on analysis
of the soil, based on nutrients that showed low availability.
Sowing was carried out 30 days after liming, using five (5) plants per pot. The species used was Brachiaria
brizantha cv. Xaraes. After 10 days of germination, there was a correction of nutrients in all treatments, and
application of the analyzed treatments. At 45 days after germination, forage cut was done, then separated the roots
from shoot. The collected material was packaged separately in paper bags and dried in an oven with forced air
circulation at a temperature of 65°C for 72 hours until constant weight. After weighing the materials, shoot dry weight,
dry weight of leaves and root dry weight were determined.
The variables evaluated were: leaves dry matter (MSF), stem + sheath (MSCB), shoot (MSPA) and root
(MSR). Statistical analysis was performed based on the average of the variables, using SAS software. ANOVA
procedure was used, applying the Tukey test at 5% depending on the F test significance level
Results and Discussion
With the regression study it was found significance (P <0.01) for the variables dry mass of leaves (MSF),
mass stem + sheath (MSCB), root mass (MSR). While the dose with sulfur was not enough to increase dry matter
production of forage.
The N doses influenced the production of MSF being the quadratic behavior response (Figure 1A). The
derivative of equation indicates that the maximum yield of 9.09 g pot-1 was found in the dose of 107.2 mg N dm-3.
According to Batista and Monteiro (2006), at first growth was observed that at low or moderate doses of nitrogen
there was an increase in dry matter yield of leaves depending primarily of nitrogen rates on grass Marandu.
Figure 1. Leaf dry matter production (1A) and stem + sheath dry matter (1B) in N does function (mg dm-3).
For the production of MSCB, the behavior observed was quadratic, where for N doses the derived indicated
that the maximum yield of 4.55 g pot-1 represented by the dose of 109.74 mg N dm-3 (Figure 1B). In B. decumbens,
the N dose of 434 mg L-1 was reported by Ferragine and Monteiro (1999) as responsible for the largest dry matter
yield of stems and sheaths at the time of the first growth. This variable can be used as a quality index pastures,
inhibiting the height of grasses, because with the increasing height of the pasture and the availability of dry matter
there is a greater forage seizure by the animal and consequently higher grazing efficiency (Alden and Whitaker, 1970).
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52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Figure 2. Shoot dry matter production (2A) and dry matter of roots (2B) due to N doses (mg dm-3).
The N rates influenced the production of MSPA, being the answer to this variable quadratic (Figure 2A). The
derivative of equation indicated that the maximum yield of 13.51 g pot-1 was found by the dose of 103.5 mg N dm-3.
These results justify the findings for MSF and MSCB, since MSPA is the sum of those two parts. Those authors are
conclusive in showing that there is a maximum production of MSF, MSCB and MSPA due to the supply of N.
Different results were found by Batista and Monteiro (2006), who found that the dry matter yield of shoots in first
growth in low N providing conditions along with the increase of sulfur did not result in increasing production.
However, these authors found that as the N dose increased associated with S dose it happened a parallel increase in
dry matter yield of shoot. Mattos and Monteiro (2003) indicated that the increase of N leads to the need to supply
more S for maximizing brachiaria responses.
Adjustments in relation to N rates studied for MSR were checked (Figure 2B), with quadratic behavior, where
the maximum production was achieved at a dose of 86.75 mg N dm-3 which had estimated productivity 8.97 g pot-1.
This result shows that there was a drastic drop in production of this variable from the optimal dose, suggesting toxicity
of this element that mainly affects the root system, considering that the nitrogen assimilation is done on a larger scale
in this plant organ (Garcez, 2013).
Conclusions
Nitrogen positively influenced the growth of Brachiaria brizantha cv. Xaraes, proving the essentiality of using
100 to 110 mg N dm-3 or 222 to 244 kg urea ha-1 when planting Xaraes grass in sandy Yellow Latosols soils of the
northeast of Para.
Acknowledgements
The Xingu farm (Castanhal-Pa) for financial research funding.
References
ALDEN, W.G.; WHITAKER, I.A. The determinants of herbage intake by grazing sheep: the inter relationship of factors
influencing herbage intake and availabity. Australian Journal of Agricultural Research, v.21, n.5, p.755-766, 1970.
BATISTA, K.; MONTEIRO, F. A. Sistema Radicular do Capim-Marandu, Considerando as Combinações de Doses De
Nitrogênio e de Enxofre. Revista Brasileira de Ciência do Solo. v. 30, p. 821-828, 2006.
FERRAGINE, M.C.; MONTEIRO, F.A. Combinação de doses de nitrogênio e potássio na nutrição mineral de capimBraquiária. Boletim de Indústria Animal, v.56, n.1, p.25-33, 1999.
GARCEZ, T. B. Aspectos metabólicos, nutricionais e produtivos de cultivares de Brachiaria e Panicum Visando eficiência
no uso de nitrogênio. Tese. Escola Superior de Agricultura “Luiz de Queiroz. Piracicaba – SP, 2013.
MALAVOLTA, E. Manual de Nutrição de Plantas. Ed. Agronômica Ceres. São Paulo-SP, 2006.
MATTOS, W.T.; MONTEIRO, F.A. Produção e nutrição de capim braquiária em função de doses de nitrogênio e enxofre.
Boletim de Indústria Animal, v.60, n.1, p.1-10, 2003.
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