Indicadores de qualidade do solo em sistema de integração lavoura-pecuária
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Data
2019-03-06
Autores
Maia, Nayane Jaqueline Costa
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O uso de indicadores é importante para avaliar mudanças na qualidade do solo em função de estratégias de manejo. O objetivo com este trabalho foi comparar o sistema integrado de lavoura-pecuária com sistemas de monocultivo de milho e de pecuária de corte nos seus efeitos em atributos químicos indicadores de qualidade do solo. Foram avaliados seis tratamentos principais, sendo dois sistemas de monocultivo (Zea mays; Urochloa brizantha cv marandu) e quatro sistemas de integração lavoura-pecuária: milho mais capim-marandu semeados simultaneamente; milho mais capim-marandu + herbicida nicosulfuron; milho mais capim-marandu semeado na adubação de cobertura do milho; milho mais capim-marandu semeado na linha e na entrelinha do milho + herbicida nicosulfuron. Os atributos do solo foram avaliados em amostras coletadas em duas profundidades, 0-0,10 e 0,10-0,20 m, e em três épocas durante um ano. O delineamento experimental foi em blocos casualizados (três) com parcelas sub subdivididas (profundidades/ épocas, respectivamente). Os indicadores avaliados foram carbono orgânico total, carbono da biomassa microbiana, carbono oxidável em solução de permanganato de potássio, índice de manejo do carbono, nitrogênio total, relação C:N do solo, nitrogênio da biomassa microbiana e relação C:N da biomassa microbiana do solo. Entre os sistemas de integração, a aplicação de nicosulfuron foi prejudicial na semeadura simultânea de milho e capim, uma vez que diminuiu o carbono da biomassa microbiana. O monocultivo de milho apresentou a menor concentração de nitrogênio da biomassa microbiana, comparado aos tratamentos em que havia a presença de animais. O mês de janeiro foi a época de coleta em que o nitrogênio da biomassa microbiana apresentou o maior teor médio. Nos tratamentos de integração foi obtida menor relação C:N da biomassa microbiana em relação ao monocultivo de milho, o que pode ser associado a processos mais rápidos de ciclagem de C e N no solo. Os tratamentos milho mais capim-marandu semeados simultaneamente; milho mais capim-marandu semeado na adubação de cobertura do milho; milho mais capim-marandu semeado na linha e na entrelinha do milho + herbicida nicosulfuron resultaram nos maiores ganhos de qualidade do solo em curto prazo, com base nos indicadores avaliados. Ainda, conseguiram manter a qualidade do solo até a camada de 0,10-0,20 m, principalmente durante as estações mais secas, de modo que podem ser considerados sistemas de maior sustentabilidade ambiental quando comparados aos monocultivos.
The use of indicators is important to evaluate changes in soil quality due to management strategies. The objective of this study was to compare the integrated crop-livestock system with maize monoculture and beef cattle systems in their effects on chemical attributes indicating soil quality. Six main treatments were evaluated: two monoculture systems (Zea mays; Urochloa brizantha cv marandu) and four crop-livestock integration systems: maize plus marandu grass seeded simultaneously; maize plus marandu grass + nicosulfuron herbicide; maize plus marandu grass sown in maize cover fertilization; maize plus marandu grass seeded on the line and between maize + herbicide nicosulfuron. Soil attributes were evaluated in samples collected at two depths, 0-0,10 and 0,10-0,20 m, and at three times for one year. The experimental design was in randomized blocks (three) with sub subdivided plots (depths / seasons, respectively). The indicators evaluated were total organic carbon, microbial biomass carbon, oxidizable carbon in potassium permanganate solution, carbon management index, total nitrogen, soil C:N ratio, microbial biomass nitrogen and microbial biomass C:N ratio from soil. Among the integration systems, the application of nicosulfuron was detrimental in the simultaneous sowing of maize and grass, since it decreased the carbon of the microbial biomass. The corn monoculture presented the lowest concentration of nitrogen in the microbial biomass, compared to the treatments in which there were the presence of animals. The month of January was the collection season in which the nitrogen of the microbial biomass presented the highest average content. In the integration treatments a lower C:N ratio of the microbial biomass was obtained in relation to the corn monoculture, which may be associated to faster cycling processes of C and N in the soil. Treatments corn plus marandu grass seeded simultaneously; maize plus marandu grass sown in maize cover fertilization; maize plus marandu grass seeded in the line and in the maize + nicosulfuron herbicide resulted in higher short-term soil quality gains, based on the indicators evaluated. Still, they managed to maintain soil quality up to the 0,10-0,20 m layer, especially during the driest seasons, so that they can be considered systems of greater environmental sustainability when compared to monocultures.
The use of indicators is important to evaluate changes in soil quality due to management strategies. The objective of this study was to compare the integrated crop-livestock system with maize monoculture and beef cattle systems in their effects on chemical attributes indicating soil quality. Six main treatments were evaluated: two monoculture systems (Zea mays; Urochloa brizantha cv marandu) and four crop-livestock integration systems: maize plus marandu grass seeded simultaneously; maize plus marandu grass + nicosulfuron herbicide; maize plus marandu grass sown in maize cover fertilization; maize plus marandu grass seeded on the line and between maize + herbicide nicosulfuron. Soil attributes were evaluated in samples collected at two depths, 0-0,10 and 0,10-0,20 m, and at three times for one year. The experimental design was in randomized blocks (three) with sub subdivided plots (depths / seasons, respectively). The indicators evaluated were total organic carbon, microbial biomass carbon, oxidizable carbon in potassium permanganate solution, carbon management index, total nitrogen, soil C:N ratio, microbial biomass nitrogen and microbial biomass C:N ratio from soil. Among the integration systems, the application of nicosulfuron was detrimental in the simultaneous sowing of maize and grass, since it decreased the carbon of the microbial biomass. The corn monoculture presented the lowest concentration of nitrogen in the microbial biomass, compared to the treatments in which there were the presence of animals. The month of January was the collection season in which the nitrogen of the microbial biomass presented the highest average content. In the integration treatments a lower C:N ratio of the microbial biomass was obtained in relation to the corn monoculture, which may be associated to faster cycling processes of C and N in the soil. Treatments corn plus marandu grass seeded simultaneously; maize plus marandu grass sown in maize cover fertilization; maize plus marandu grass seeded in the line and in the maize + nicosulfuron herbicide resulted in higher short-term soil quality gains, based on the indicators evaluated. Still, they managed to maintain soil quality up to the 0,10-0,20 m layer, especially during the driest seasons, so that they can be considered systems of greater environmental sustainability when compared to monocultures.
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Palavras-chave
Carbono orgânico, Nitrogênio orgânico, Biomassa microbiana do solo, Índice de manejo, Sistema de integração lavoura-pecuária