Crescimento aéreo e radicular da soja e de plantas de cobertura em camadas compactadas de solo
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Data
2006-02-01
Autores
Foloni, José Salvador Simoneti
Lima, Sérgio Lazaro de [UNESP]
Büll, Leonardo Theodoro [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
O cultivo de plantas de cobertura com sistema radicular vigoroso em rotação de culturas pode melhorar a qualidade física de solos compactados. O objetivo deste trabalho foi avaliar o crescimento aéreo e radicular da soja e de cinco espécies utilizadas como plantas de cobertura de verão (guandu, guandu anão, mucuna preta, labe labe e crotalária juncea), em solo submetido a três níveis de compactação em subsuperfíce. Utilizou-se um Nitossolo Vermelho argiloso em vasos montados com anéis de PVC sobrepostos, com diâmetro interno de 20 cm e altura de 50 cm. A camada compactada localizada de 20-30 cm de profundidade foi caracterizada pelas densidades do solo de 1,13, 1,34 e 1,56 g cm-3 e 0,26, 0,66 e 1,98 MPa de impedância mecânica, respectivamente. Aos 60 dias da emergência das plantas, determinaram-se as massas da matéria seca da parte aérea e das raízes, a densidade do comprimento radicular e o diâmetro médio radicular. Apesar de alterar a distribuição do sistema radicular ao longo do perfil do solo, o impedimento físico em subsuperfície não diminuiu a produção total de raízes da soja e dos adubos verdes, com exceção da crotalária juncea. A mucuna preta foi a leguminosa mais tolerante e a soja a mais sensível à compactação do solo. O sistema radicular da crotalária juncea apresentou potencial de formação de bioporos compatível ao da mucuna preta, apesar de ter sido relativamente mais sensível à compactação do solo. O diâmetro médio das raízes da soja e da crotalária juncea apresentou correlação significativa com o crescimento radicular dentro da camada de solo compactado.
The cultivation of cover crops with vigorous root systems in crop rotation can improve the physical quality of compacted soils. The objective of this study was to evaluate shoot and root growth of soybean (Glycine max) and five species used as summer cover crops (Cajanus cajan, Cajanus cajan var. small, Mucuna aterrima, Dolichos lab lab and Crotalaria juncea) in a soil submitted to three different levels of subsurface compaction. Plants were grown in pots assembled with three PVC rings, 50 cm high and with 20 cm internal diameter, filled with a clay-textured Red Nitosol. The soil layer at 20-30 cm depth was compacted to a bulk density of 1.13, 1.34 and 1.56 g cm-3 with 0.26, 0.66 and 1.98 MPa mechanical impedances, respectively. Sixty days after plant emergence, plants were harvested and it was determined the shoot and root dry matter, root length density, and root mean diameter. In spite of altering the root system distribution along the soil profile, the subsoil physical impediment did not reduce the total root dry matter of soybean and cover crops, except for Crotalaria juncea. Mucuna aterrima was the most tolerant and soybean the most sensitive of the leguminous species to soil compaction. Crotalaria juncea roots showed a potential of forming biopores comparable to those of Mucuna aterrima, in spite of being relatively more sensitive to soil compaction. Mean root diameter of soybean and Crotalaria juncea showed significant correlation to root growth in the compacted soil layer.
The cultivation of cover crops with vigorous root systems in crop rotation can improve the physical quality of compacted soils. The objective of this study was to evaluate shoot and root growth of soybean (Glycine max) and five species used as summer cover crops (Cajanus cajan, Cajanus cajan var. small, Mucuna aterrima, Dolichos lab lab and Crotalaria juncea) in a soil submitted to three different levels of subsurface compaction. Plants were grown in pots assembled with three PVC rings, 50 cm high and with 20 cm internal diameter, filled with a clay-textured Red Nitosol. The soil layer at 20-30 cm depth was compacted to a bulk density of 1.13, 1.34 and 1.56 g cm-3 with 0.26, 0.66 and 1.98 MPa mechanical impedances, respectively. Sixty days after plant emergence, plants were harvested and it was determined the shoot and root dry matter, root length density, and root mean diameter. In spite of altering the root system distribution along the soil profile, the subsoil physical impediment did not reduce the total root dry matter of soybean and cover crops, except for Crotalaria juncea. Mucuna aterrima was the most tolerant and soybean the most sensitive of the leguminous species to soil compaction. Crotalaria juncea roots showed a potential of forming biopores comparable to those of Mucuna aterrima, in spite of being relatively more sensitive to soil compaction. Mean root diameter of soybean and Crotalaria juncea showed significant correlation to root growth in the compacted soil layer.
Descrição
Palavras-chave
adubos verdes, raízes, rotação de culturas, densidade do solo, Glycine max, green manures, roots, crop rotation, soil bulk density, Glycine max
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 30, n. 1, p. 49-57, 2006.