trabalho completo - 52ª Reunião Anual da Sociedade Brasileira de

52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Eficiência nutricional e aproveitamento do nitrogênio pela Brachiaria decumbens cv. Basilisk sob doses de
água residuária de suínos1
Igor Machado Ferreira2, Onofre Barroca de Almeida Neto3, Bruno Grossi Costa Homem4, Márcio André Stefanelli
Lara5, Marisa Senra Condé6, Iury Augusto de Freitas Cruvinel2, Michael David Batista Luaemar de Oliveira 4.
1
Parte da Iniciação Científica do primeiro autor, financiada pela FAPEMIG
Graduandos em Zootecnia, Universidade Federal de Lavras (UFLA), [email protected]; [email protected]
3
Doutor em Engenharia Agrícola, Professor do Instituto Federal de Educação, Ciência e Tecnologia do Sudeste Minas Gerais, Câmpus Rio
Pomba, [email protected]
4
Mestrandos em Zootecnia, Universidade Federal de Lavras (UFLA), [email protected]; [email protected]
5
Doutor em Ciência Animal e Pastagens, Professor da Universidade Federal de Lavras (UFLA), [email protected]
6
Graduação em Zootecnia; Instituto Federal de Educação, Ciência e Tecnologia do Sudeste Minas Gerais, Câmpus Rio Pomba;
[email protected]
2
Resumo: A eficiência de utilização do nitrogênio no sistema pastoril é muito baixa. Diante disto, objetivou-se
avaliar índices de eficiência de utilização e de aproveitamento do nitrogênio pela forrageira Brachiaria decumbens
cv. Basilisk sob adubação com doses de água residuária de suínos (ARS). O estudo foi conduzido no IF Sudeste
MG, Campus Rio Pomba. O experimento foi conduzido em casa de vegetação, utilizando-se vasos contendo 6 dm³
de solo (6 kg), no período de 09/2012 à 04/2013. Os tratamentos foram alocados em delineamento de blocos
completos casualizados com parcelas subdivididas e quatro repetições; avaliando-se a gramínea sob quatro níveis
de adubação com ARS (0, 225, 450 e 675 mL.dm-³, que corresponderam a aplicação de 1.632, 3.261 e 4.890
mg.dm-3 de N), totalizando 16 unidades experimentais. A adubação com ARS foi realizada após o corte da
forrageira a 5 cm do solo, para avaliação da massa seca e os teores de Nitrogênio (N) nos tecidos. Com esses
resultados, avaliaram-se os índices de Extração de N (EN), Eficiência de Utilização do N (EUN), Recuperação do N
Aplicado (RNA), Eficiência Agronômica do N Aplicado (EANA) e Eficiência Fisiológica (EF). Os resultados
mostraram que a EA e EUN aumentaram com as doses de ARS (P=0.0003 e 0.0002, respectivamente), enquanto
que a RNA, EANA e a EF diminuíram com o aumento das doses de ARS aplicadas (P=0.054, P=0.036 e P=0.030,
respectivamente). Ações de manejo devem ser adotadas para que se otimize o uso do nutriente pela planta.
Palavras–chave: eficiência no uso do nitrogênio, fertirrigação, forragem
Nutritional efficiency and use of nitrogen by Brachiaria decumbens cv. Basilisk under doses of swine
wastewater
Abstract: The efficiency of utilization of nitrogen in the grazing system is very poor. Before that, evaluating the
indices of efficiency of utilization and of exploitation of nitrogen by forage Brachiaria decumbens cv. Basilisk
under fertilization with doses of swine wastewater (SW) was intended. The study was conducted at Southeast IF
MG, Rio Pomba Campus. The experiment was conducted in a greenhouse utilizing pots containing 6 dm³ of soil (6
kg), in the period of 09/2012 to 04/2013. The treatments were arranged in a randomized complete block design with
split plots and four replications; evaluating the grass under four levels of fertilization with ARS (0, 225, 450 and
675 mL.dm-³, which corresponded to the application of 1.6, 3.2 and 4.8 g.dm-3 de N), amounting to 16 experimental
units. The fertilization with SW was performed after the forage cutting at 5 cm from soil, for evaluation pf the dry
matter and contents of Nitrogen (N) in the tissues. From these results, the indices of N extraction (NE), of N
utilization efficiency (NUE), applied N recovery (ANR), applied N agronomical efficiency (ANAE) and
physiological efficiency (PE) were evaluated. The results showed that both NE and NUE increased with the doses
of ARS (P=0.0003 and 0.0002, respectively), while ANR, ANAE and PE decreased with the increase of the applied
doses of ARS (P=0.054, P=0.036 and P=0.030, respectively). Management actions should be adopted to optimize
the use of the nutrient by the plant.
Keywords: efficiency in nitrogen use, fertirrigation, forage
Introduction
Pastures constitute the main and cheapest sources of feeds for the diets of cattle in Brazil. But, the
inadequate use of pastures has reflected into poor performance indices of Brazilian livestock production. The
fertilization of pastures with pig liquid wastes can be an interesting tool, for it constitutes an alternative source of
fertilization, since nitrogen present in the liquid waste is the leading responsible for the increased yield. But the
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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
efficiency of the use of nitrogen for food production in the world is very low and the recovery of nitrogen can range
with the plant species, management practices, soil properties, environmental conditions and utilized nitrogen source
(Espindula et. al, 2010). Before that, it was aimed, with the present work to evaluate the indices of efficiency of
utilization and exploitation of nitrogen by forage plant Brachiaria decumbens cv. Basilisk under fertilization with
doses of swine wastewater.
Material and Methods
The experiment was conducted in Southeast IF MG, Rio Pomba Campus (21 ° 14'30.78" south latitude and
43° 09'39.31" west longitude). The climate regime is Cwa: humid tropical climate with dry winter and hot summer
in Koppen classification. The treatments were arranged in a randomized complete block design in split plot scheme
with four replications; evaluating grass Brachiaria decumbens cv. Basilisk under four fertilization levels with SW
(0, 225, 450 and 675 mL.dm-³ corresponding to the application of 1.6; 3.2 and 4.8 g.dm-3 of N), amounting to 16
experimental units. The experiment was conducted in a greenhouse using pots containing 6 dm³ of soil (6 kg). The
soil used was Dystrophic Red-Yellow Latosol (Oxisol), clayey textured, which was amended by means of liming
for rise of the base saturation to 50% and was given the equivalent to 75 mg.dm-3 of P2O5 and 30 mg.dm-3 of K2O.
The sowing of the grass was performed directly in the pots for the obtaining of the final number of four
plants. As to water requirement, the pots were maintained at field capacity, their being monitored twice a day. The
cuttings occurred at 28-day intervals, the first one was for making the sward uniform and the other four were for
evaluation where all the plants of each treatment were cut at 5cm from soil level. The doses of SW were split into
four and applied after each cutting. The material collected in the pots was placed in plastic bags and shipped to the
laboratory where the material was placed in a forced air oven at the temperature of 60°C for 72 h. Later, the
samples were ground in a Wiley mill with a 1 mm sieve screen. The chemical analysis of the plant nitrogen was
done to obtain the total nitrogen content. The values of N accumulation were obtained by N content in the plant and
dry matter yield. With the data of dry mass and N accumulation, the following indices were calculated: N
Extraction (NE), N Use Efficiency (NUE), Applied N Recovery (ANR), Agronomic Efficiency of Applied N
(AEAN) and Physiological Efficiency (PE) according to Fageria (1998). The data were subjected to analysis of
variance, with further regression analysis by means of the R program. The adopted level of probability was 10%.
Results and Discussion
NE was influenced (P = 0.0003), linear effect being observed according to the doses of SW used (Figure 1).
Similar results were found by Scheffer-Basso et al. (2008) on natural pasture, who found that the amount of N
extracted by the pasture increased linearly according to the doses of leachate.
NUE increased quadratically (P = 0.0002) with the addition of the doses of SW applied (Figure 1) and their
values ranged from 0.54 (without application of SW) to 2.85 g2.mg-1 (at the dose of 450 mL.pot-1). The greatest
NUE was observed at the dose of 511 mL.pot-1, showing an increase of 582% in relation to the non-application of
SW. Siddiqi & Glass (1981) reported that plant growth is also related to the concentration of the nutrient in the
tissues and not only in the absolute amount accumulated, for growth occurs only from a minimum concentration in
the plant tissue, which is different among species or varieties. ANR was influenced by the doses of SW (P = 0.054)
presenting a linear decrease with increasing doses SW (Figure 1). Research results have shown that ANR decreases
as the dose applied to the soil is increased (Primavesi et al., 2006), where at the highest doses there is a greater
chance of nutrient losses by volatilization, leaching, denitrification and surface washing.
AEAN (refers to the additional dry matter yield in the fertilized plots in relation to the unfertilized by unit
of N applied) and PE (represents the additional dry matter yield by the forage plant in the fertilized plots in relation
to the unfertilized per unit of additional N accumulated in the plants of those plots) decreased in a linear way
(P=0.036 and P=0.030, respectively) by the application of doses of SW (Figure 2).
In a study of agronomic and physiological efficiency of marandu grass, Primavesi et al. (2006) found that the
best indices occurred when the smallest doses of N were applied, reduction in the values of both EANA and EF
occurring with increased doses of N. That can be related to the response of the plant according to dry mass yield,
for in relation to the concentration of N in the tissues, its point of maximum accumulation occurs at the highest
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
Figure 1. N Extraction (a), N Use Efficiency (b), Applied N Recovery (c), Agronomic Efficiency of
Applied N (d) and Physiological Efficiency (e), according to doses of ARS in Brachiaria
decumbens cv. Basilisk (mean of four cuttings).
Conclusions
The extraction of nitrogen and the efficiency of utilization of nitrogen by Brachiaria decumbens cv.
Basilisk increased, while the recovery of applied nitrogen, the agronomical efficiency and the physiological
efficiency decreased with increasing doses of pig wastewater applied. In that way, management actions should
be adopted for the use of nutrient by the plant to be optimized.
Acknowledgements
To Southeast IF MG, Rio Pomba Campus, by the support to this work and to FAPEMIG by the grant of the
scholarship.
References
Espindula, M. C.; Rocha, V. S.; Souza, M. A. de; Grossi, J. A. S.; Souza, L. T. de. 2010. Doses e formas de
aplicação de nitrogênio no desenvolvimento e produção da cultura do trigo. Ciência e Agrotecnologia 34:14041411.
Fageria, N .K. 1998. Otimização da eficiência nutricional na produção das culturas. Revista Brasileira de
Engenharia Agrícola Ambiental 2:6-16.
Primavesi, O.; Primavesi, A. C.; Correa, L. A.; Silva, A. G.; Cantarella, H. 2006. Lixiviação de nitrato em
pastagens de coastcross adubada com nitrogênio. Revista Brasileira de Zootecnia 35:683-690.
Scheffer-Basso, S. M.; Scherer, C. V.; Ellwanger, M. F. 2008. Resposta de pastagens perenes à adubação com
chorume suíno: pastagem natural. Revista Brasileira de Zootecnia 37:221-227.
Siddiqi, M. Y.; Glass, A. D. M. 1981. Utilization index: a modified approach to the estimation and comparison of
nutrient utilization efficiency in plants. Journal of Plant Nutrition 4:289-302.
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