52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Efeito da decomposição anaeróbica de resíduo suíno e sua utilização como adubo orgânico
Brenda Santaiana Prato1, Carlos Alexandre Oelke2, Paula Gabriela da Silva Pires2, Lucas Marques Vilella3,
Darlene Liara Curti Morais4, Paula Raymundo Nunes5, Andréa Machado Leal Ribeiro6
Graduação em Zootecnia Universidade Federal do Rio Grande do Sul – UFRGS email: [email protected]
Pós-graduação Universidade Federal do Rio Grande do Sul – UFRGS
3
Graduação em Zootecnia Universidade Federal do Rio Grande do Sul – UFRGS
4
Graduação em Agronomia Universidade Federal do Pampa–Unipampa
5
Graduação em Medicina Veterinária Universidade Federal do Pampa - Unipampa
6
Departamento de Zootecnia – Universidade Federal do Rio Grande do Sul – UFRGS
1
2
Resumo: O objetivo do trabalho foi avaliar a utilização da palha de arroz em diferentes períodos sob a
composição e secagem espontânea de dejetos suínos e seu potencial uso como adubo orgânico. Os dejetos líquidos
de suínos foram depositados em tanques de alvenaria de 1x2x1 m em dois tratamentos: com e sem a adição de casca
de arroz. No tratamento 1 as composteiras receberam 1.56 m3 de dejetos e no tratamento 2 receberam 1.1 m3 de
dejetos e 60 kg de casca de arroz, o que correspondeu a 23 cm. Foram coletadas amostras nos dias 125 e em um
período superior a 267 dias. Realizou-se as análises de umidade, carbono, nitrogênio e a relação carbono:nitrogênio.
Os tratamentos não influenciaram a umidade, no entanto a umidade foi reduzindo-se ao longo do tempo. Os níveis
de nitrogênio aos 125 dias atende a recomendação da legislação para composição de adubo orgânico. Para o período
de 267 dias somente o tratamento sem casca de arroz apresentou nível de nitrogênio acima do limite mínimo
recomendado. Para o variável carbono orgânico não houve diferença significativa entre os tratamentos, sendo
observado apenas a influência do dia na composição final. A relação carbono:nitrogênio apresentou resultados
inferiores ao recomendado. O período de 125 dias apresentou os melhores resultados, demonstrando a maturação do
composto, porém, não atendeu os níveis de umidade necessários, indicando assim a necessidade de adaptações de
outras metodologias que viabilizem seu uso como fertilizante orgânico.
Palavras–chave: dejetos de suínos, carbono, nitrogênio, nutrientes
Effect of the anaerobic digestion of swine waste and its usage as organic fertilizer
Abstract: The objective of this paper was to analyze the usage of rice straw in different evaluation periods under
the composting and spontaneous drying of swine waste and its potential as organic fertilizer. The liquid waste of
pigs was placed in masonry tanks of 1.0 x 2.0 x 1.0 m and two treatments were used: with and without rice straw.
For treatment 1, the compost tanks received 1.56 m³ of waste and 60 kg of rice straw, which amounted 23 cm. The
samples were collected in the first period of 125 days and in a period longer than 267 days. Humidity, carbon,
nitrogen and the carbon-to-nitrogen ratio were analyzed. The treatments did not influence the humidity, however, it
decreased over time. The nitrogen levels in the 125 days period are compatible to those required by legislation to
compose the organic fertilizer. In the 267 days period, only the treatment without de rice straw showed nitrogen
levels above the recommended minimum. In the organic carbon variable there was no significant difference
between treatments, only the influence of time was observed in the final composition. The carbon-to-nitrogen ratio
presented results below the recommended. The 125 days period presented better results, showing the maturation of
the compost. However, it did not reach the necessary levels of humidity, thus indicating the need to adapt other
methodologies that would enable the use of swine waste as organic fertilizer.
Keywords: swine waste, carbon, nitrogen, nutrients
Introduction
The residues produced by animals can be used as an alternative in fertilization, for they contain a series of
readily available chemical elements that can be absorbed by plants. Therefore, the swine waste can be considered a
good fertilizer, because it presents itself as an excellent source of nutrients, specially nitrogen, phosphorus and
potassium, which can replace totally or partially the chemical fertilizer (VIELMO et al., 2011).
The fermentation process of the organic matter in the manure aims at reducing or inactivating the pathogenic
microorganisms and the toxicity of these residues before they are applied to the soil. After the fermentation process,
the plants growing is stimulated due to the presence of mineral nutrients, beneficial microorganisms and humic
substances.
For the utilization of swine waste as compost, it is important to assure a minimum amount of time for
fermentation and decomposing of these residues before using them, this way reducing the risks of soil
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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
contamination. The objective of this work was to verify the effects of rice straw in different evaluation periods
under the composition and the spontaneous drying of swine waste and its potential usage as organic fertilizer.
Material e Methods
The experiment was conducted at farm I from Yargo Suinocultura, located in the city of Itaqui-RS, close to
the south access of BR-472 road, from January 2012 to February 2013. The liquid swine waste was placed in
masonry tanks, called compost tanks, measuring 1,0m x 2,0m x 1,0m. The tanks were placed in a location protected
from rain by the installation of a roof and walls made with transparent plastic, similar to a greenhouse.
Two treatments were used in this experiment. The reference used for the distribution of the waste and the
rice straw was based on the height of the tanks, wherein the adopted height was 78cm in both treatments. In
treatment 1 the tanks received 1,56m³ of waste, whereas in treatment 2 the tanks received 1,1m³ of waste and 60kg
of rice straw, which corresponded to a 23cm height and resulted in a final height of 78cm. A total of 13,3m³ of
waste and 300kg of rice straw were used. After filling the tanks with the waste and the rice straw, the composts
homogenization was proceeded, followed by the sample collection, which were sent to the Soil Analysis Laboratory
at UFRGS, where the analysis of humidity, organic carbon, nitrogen, carbon-nitrogen ratio were tested. The
humidity analysis was conducted based on the gravimetric methods, the organic carbon analysis was based on
humid combustion (Walkey Black), and the nitrogen analysis was based on the TKN method. Afterwards, as the
complete drying of the composts did not occur, samples were collected from the 125 days period and the period
longer than 267 days, which were send again to the laboratory.
The experiment lasted for 393 days, wherein from day 267 on there was the spontaneous drying of some
tanks. In these cases the samples were sent to the laboratory. On the day 393, the experiment was considered
completed, and samples of the remaining tanks were collected, regardless of the material being dry or liquid. The
research was conducted with two treatments and five repetitions each, therefore using 10 storage tanks, each
considered one experimental unity. The interaction effect between treatments and days, as well as their comparison
mean were analyzed using PROC GLM (General Linear Models) of the statistics software SAS. Afterwards, to
compare the means, the figures of the days were submitted to the Tukey test with 5% error probability.
Results and Discussion
According to the results (Table 1), the humidity was not influenced by the treatments (P=0.078). However,
there was statistical difference (P=0.0001) regarding the period of observation, wherein the humidity decreased
throughout the time, reaching a 18.79% mean in the period longer than 267 days. According to FATMA
(Environment Foundation from the State of Santa Catarina) (Portaria nº 02 from 2003), in order to being applied to
the soil, the swine waste must remain stored for a minimal period of 120 days. Thus, in both treatments it could
have been applied to the soil within day 125. The advantage of using both treatments in the period longer than 267
days is the lower humidity (18.87%), for the higher the waste humidity, the higher are the transportation costs when
considering the amount of nutrients deposited on the soil (Oliveira, 2004).
For the organic carbon variable, there was no difference (P>0.05) between treatments, only the day influence
was observed in the final compost (P=0001). For the nitrogen variable, there was interaction (P=0.0004) between
the treatments and the observation days. An increase in the nitrogen concentration was observed in the treatment
with rice straw by the day 125, which was not verified when compared to the treatment without rice straw. This fact
can be mainly explained by the availability of the nitrogen obtained through the composting of the plant material at
the beginning of the fermentation process.
When considering the whole storage period, a decrease in the nitrogen concentration was observed.
According to the Brazilian laws (Brasil, 2005; 2006), an organic compound can only be commercialized as fertilizer
if it presents a minimum of 15% of organic carbon (C), 1% of total nitrogen, 18:1 of C-N ratio, 20:1 of CEC-C ratio
and pH 6.0, in addition to the humidity maximum (50%) and low contamination with parasites, enteropathogenic
microorganisms indicators, and toxic metals. Such legal requirement aims at establishing a quality pattern for
organic compounds, taking into account the environmental protection and the agronomic efficiency of these
materials (Higarashi et al., 2008; Daza-Torres et al., 2008). From the results presented in Table 1, it can be said that
the nitrogen levels on the day 125 met the minimum requirements demanded by law, reaching 2.7 and 11.7% for
the treatments without and with rice straw, respectively. On the period longer than 267 days, only the treatment
without rice straw presented a nitrogen level (3.25%) superior to the minimum required.
Kiehl (1985) describes that for rapid decomposition, the figures of the C-N ratio must be around 26:1 to
35:1, and points out that the swine manure, as observed in this experiment, presents a much lower C-N ratio,
resulting in a great nitrogen loss through volatilization, as shown previously in the nitrogen data.
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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
Table 1. Mean figures of humidity, organic carbon, nitrogen and carbon-nitrogen ratio in the treatments with and
without rice straw in the different periods
Variable
Humidity (%)I
Organic Carbon (g/kg) I
Treatment/Day
Without R. S.
With R. S.
Mean
Without R. S.
With R. S.
Mean
0
99.42
97.61
98.52a
357.35
263.86
310.61a
125
99.52
72.38
85.95a
105.98
41.97
73.98a
18.79b
> 267
23.25
14.33
2.66
3.86
3.26b
Mean
74.06
61.44
155.33
103.23
Probabilities
Treatments
NS
NS
Day
***
***
Treatment*Day
NS
NS
C.V. (%)II
23.20
59.39
Variable
Nitrogen(g/kg)I
C/N RatioI
Treatment/Day
Without R. S.
With R. S.
Mean
Without R. S.
With R. S.
Mean
0
86.38a
16.02b
51.2
4.15a
16.1a
10.12
125
27.71b
117.54ª
72.62
4.06a
0.46b
2.26
> 267
32.54b
7.4ab
19.97
0.09b
0.52b
0.3
Mean
48.88
46.99
2.76
5.69
Probabilities
Treatment*day
**
**
C.V. (%)II
73.9
85.17
Treatments: Waste with and without rice straw; Different lower case letters in the same column diverge in the Tukey test with 5% error
probability; I - Error probability of the treatments interaction and the evaluation periods; II - Coefficient of variation. With R. S.: with rice
straw; Without R. S.: without rice straw; C/N ratio: Carbon-Nitrogen Ratio
(*P<0.05; **P<0.01; ***P<0.001; NS: Not Significant).
Conclusions
The 125 day storage period presented better results, showing the compost maturation. However, it did not
meet the necessary humidity levels, thus indicating the need to adapt other methodologies that would enable the use
of swine waste as organic fertilizer.
Reference
Fundação do Meio Ambiente do Estado de Santa Catarina (FATMA). 2003. Portaria nº02 de 09 de janeiro de 2003
que disciplina o ordenamento e a tramitação dos processos de licenciamento ambiental e dá outras providências.
Portaria nº 002/03. Florianópolis, Diário Oficial de Santa Catarina, p.75-80.
Kiehl, J. E. 1985. Fertilizantes orgânicos. Piracicaba: Agronômica Ceres, 492p.
Oliveira, P. A. V. 2004. Tecnologias para o Manejo de Resíduos na Produção de Suínos. Manual de Boas Práticas.
Embrapa Aves e Suínos. Concórdia. 109 p.
Vielmo, H.; Bona Filho, A.; Brugnara Soares, A.; Simioni Assmann T.; Adami, P. F. 2011. Effect of fertilization
with fluid swine slurry on production and nutritive value of Tifton 85. Revista Brasileira de Zootecnia. 40:60-68.
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