Física do solo e matéria orgânica em sistemas de produção agrícola de Cerrado
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2020-05-29
Autores
Silva, Juslei Figueiredo da
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Universidade Estadual Paulista (Unesp)
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Em condições de clima tropical de Cerrado ocorre rápida decomposição dos resíduos vegetais e o período seco dificulta o estabelecimento de culturas na entressafra. Por isso, nessas regiões, plantas forrageiras têm viabilizado o sistema de semeadura direta, mantendo o solo coberto no período seco, aportando resíduos vegetais, que auxiliam na cobertura e estruturação do solo. O objetivo desta pesquisa foi avaliar atributos físicos do solo e a matéria orgânica em diferentes sistemas de produção no Cerrado, envolvendo o cultivo de Urochloa brizantha cv. Piatã, em monocultivo ou em sucessão com as culturas de soja e milho. A pesquisa foi conduzida durante a safra 2016/17 na Embrapa Milho e Sorgo em Sete Lagoas-MG, em Latossolo Vermelho-escuro A moderado, textura muito argilosa, fase cerrado subcaducifólio, relevo suave ondulado. O experimento foi implantado na safra 2010/2011. O delineamento experimental foi em blocos ao acaso com três repetições e parcelas de 168 m2. Os tratamentos foram constituídos por nove sistemas de produção e uma área de mata nativa (Cerrado), sendo eles: 1- Milho solteiro em sucessão anual (M); 2- Milho consorciado com U. brizantha cv. Piatã em sucessão anual (MP); 3- Soja em sucessão anual (S); 4- Pastagem de Piatã implantada em cultivo solteiro (P); 5- Consórcio Milho+Piatã e Soja em rotação anual (MP/S); 6- Sequência de consórcio Milho+Piatã e Pastagem de Piatã em rotação anual (MP/P); 7- Sequência de consórcio Milho+Piatã e pastagem de Piatã por dois anos (MP/P/P); 8- Sequência de consórcio Milho+Piatã, pastagem de Piatã e Soja em rotação anual (MP/P/S); 9- Sequência de Soja, consórcio Milho+Piatã e pastagem de Piatã por dois anos em rotação (S/MP/P/P); 10- Cerrado nativo. Foram realizadas amostragens de solo para análises de C e N, fracionamento físico e químico da MOS e física do solo. Os sistemas de produção influenciaram o carbono orgânico total (COT) e os atributos físicos do solo, principalmente nas camadas superficiais, levando a alterações na qualidade da MOS. O COT foi em média 15% (MP, MP/S e MP/P) a 31% (S) menor que no CE, para a camada 0,0-0,20 m. O IMC nas áreas cultivadas ficou abaixo da área referência em 0,0-0,10 m, e houve aumento neste índice conforme o aumento de profundidade. O índice S demostrou boa qualidade estrutural do solo, porém houve menor retenção de água no solo nos monocultivos de S e M. Para o Cerrado de Minas Gerais, a utilização da forrageira U. brizantha cv. Piatã na sucessão de culturas em sistemas de produção sob SSD contribui para melhorias na qualidade do solo.
Under conditions of tropical Cerrado climate, rapid decomposition of plant residues occurs and the dry season makes it difficult to establish crops in the off-season. For this reason, in these regions, forage plants have made the direct seeding system viable, keeping the soil covered in the dry period, providing vegetable residues, which help in covering and structuring the soil. The objective of this research was to evaluate physical attributes of the soil and organic matter in different production systems in the Cerrado, involving the cultivation of Urochloa brizantha cv. Piatã, in monoculture or in succession with soybean and corn crops. The research was conducted during the 2016/17 harvest at Embrapa Corn and Sorghum in Sete Lagoas-MG, in a moderate dark red Latosol, very clayey texture, subcaduciferous cerrado phase, smooth wavy relief. The experiment has been conducted in no-till since 2010.The experimental design is in randomized blocks with three replications and plots of 168 m2 (12 x 14 m). The treatments constitute nine production systems and an area of native forest (Cerrado), which are: 1- Single corn in annual succession (M); 2- Corn intercropped with U. brizantha cv. Piatã in annual succession (MP); 3- Soy in annual succession (S); 4- Pasture of U. brizantha cv. Piatã implanted in single cultivation (P); 5- Consortium Corn + Piatã and Soy in annual rotation (MP/S); 6- Consortium sequence Corn + Piatã and Piatã Pasture in annual rotation (MP/P); 7- Consortium sequence Corn + Piatã and pasture of Piatã for two years (MP/P/P); 8- Consortium sequence Corn + Piatã, pasture of Piatã and Soy in annual rotation (MP/P/S); 9- Soybean sequence, Corn + Piatã consortium and Piatã pasture for two years in rotation (S/MP/P/P); 10- Native Cerrado. Soil samplings were carried out for total C and N analyzes, soil C/N ratio, and organic matter through physical and chemical fractionation. The production systems influenced the organic carbon (SOC) and the physical attributes of the soil, mainly in the superficial layers, leading to changes in the quality of organic matter (SOM). The SOC was on average 15% (MP, MP/S and MP/P) at 31% (S) lower than in the CE, for the layer 0.0-0.20 m. The carbon management index (CMI) in the cultivated areas was below the reference area at 0.0-0.10 m, and there was an increase in this index as the depth increased. The S index showed good structural quality of the soil, even so there was less water retention in the soil in the monocultures of S and M. For the Cerrado of Minas Gerais, the use of forage U. brizantha cv. Piatã in the succession of crops in production systems under SSD contributes to improvements in soil quality.
Under conditions of tropical Cerrado climate, rapid decomposition of plant residues occurs and the dry season makes it difficult to establish crops in the off-season. For this reason, in these regions, forage plants have made the direct seeding system viable, keeping the soil covered in the dry period, providing vegetable residues, which help in covering and structuring the soil. The objective of this research was to evaluate physical attributes of the soil and organic matter in different production systems in the Cerrado, involving the cultivation of Urochloa brizantha cv. Piatã, in monoculture or in succession with soybean and corn crops. The research was conducted during the 2016/17 harvest at Embrapa Corn and Sorghum in Sete Lagoas-MG, in a moderate dark red Latosol, very clayey texture, subcaduciferous cerrado phase, smooth wavy relief. The experiment has been conducted in no-till since 2010.The experimental design is in randomized blocks with three replications and plots of 168 m2 (12 x 14 m). The treatments constitute nine production systems and an area of native forest (Cerrado), which are: 1- Single corn in annual succession (M); 2- Corn intercropped with U. brizantha cv. Piatã in annual succession (MP); 3- Soy in annual succession (S); 4- Pasture of U. brizantha cv. Piatã implanted in single cultivation (P); 5- Consortium Corn + Piatã and Soy in annual rotation (MP/S); 6- Consortium sequence Corn + Piatã and Piatã Pasture in annual rotation (MP/P); 7- Consortium sequence Corn + Piatã and pasture of Piatã for two years (MP/P/P); 8- Consortium sequence Corn + Piatã, pasture of Piatã and Soy in annual rotation (MP/P/S); 9- Soybean sequence, Corn + Piatã consortium and Piatã pasture for two years in rotation (S/MP/P/P); 10- Native Cerrado. Soil samplings were carried out for total C and N analyzes, soil C/N ratio, and organic matter through physical and chemical fractionation. The production systems influenced the organic carbon (SOC) and the physical attributes of the soil, mainly in the superficial layers, leading to changes in the quality of organic matter (SOM). The SOC was on average 15% (MP, MP/S and MP/P) at 31% (S) lower than in the CE, for the layer 0.0-0.20 m. The carbon management index (CMI) in the cultivated areas was below the reference area at 0.0-0.10 m, and there was an increase in this index as the depth increased. The S index showed good structural quality of the soil, even so there was less water retention in the soil in the monocultures of S and M. For the Cerrado of Minas Gerais, the use of forage U. brizantha cv. Piatã in the succession of crops in production systems under SSD contributes to improvements in soil quality.
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Palavras-chave
Semeadura direta, Urochloa, Substâncias húmicas, Qualidade do solo, No-till, Humic substances, Soil quality