Sistema radicular e nutrição da soja em função da compactação do solo
Data
1994-01-01
Autores
Rosolem, Ciro Antonio [UNESP]
Almeida, Ana Cristina da Silveira [UNESP]
Sacramento, Luiz Vitor Silva do [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Agronômico de Campinas
Resumo
A compactação do solo diminui o crescimento radicular, podendo afetar tanto o desenvolvimento quanto a produtividade da soja. No presente trabalho, estudaram-se os efeitos da compactação subsuperficial na morfologia radicular da soja (Glycine max L. Merrill), procurando relacioná-los ao crescimento e à nutrição da planta. O 'Primavera' foi cultivado até os 37 dias da emergência, em vasos onde a camada de 15-18,5 cm de profundidade foi campactada a 1,03, 1,25, 1,48 e 1,72 g/cm³, em um latossolo vermelho-escuro com 80% de areia e 16% de argila e cuja compactação em subsuperfície levou a um acúmulo de raízes na camada superficial do vaso, sem grandes conseqüências na nutrição da planta. Na densidade aparente de 1,72 g/cm3, as raízes não conseguiram penetrar, embora já houvesse alguma restrição ao crescimento na densidade de 1,25 g/cm³. Quando a camada compactada apresentava resistência à penetração de 0,69 MPa, houve uma redução de 50% no crescimento radicular da soja.
Soil tillage can originate compacted layers in the soil subsurface. This compaction reduces root growth, plant development and eventually soybean yields. This study examined the effects of subsurface compaction on soybean root growth and morphology as related to plant growth and mineral nutrition. Soybean plants cv. Primavera were grown up to 37 days from seedling emergence in pots where a compacted layer was set at the 15.0 to 18.5 cm depth. This layer was compacted to bulk densities of 1.03, 1.25, 1.48 and 1.72 g/cm³, corresponding to cone penetrometer resistances of 0.05, 3.0, 7.5 and 2.0 MPa, respectively. The soil was a Dark Red Latosol (Haplortox), sandy loam, with 80% of sand and 16% of clay. Soil subsurface compaction led to a higher concentration of roots in the surface layer of the pots, without significant effects on plant canopy growth and nutrition. In the presence of a compacted layer the roots were shorter, but nutrient absorption/cm of root was higher. There was some restriction to root growth in the bulk density of 1.25 g/cm³, but there was necessary a bulk density of 1.72 g/cm³ to inhibit completely the root growth. Soybean root growth was decreased by 50% when the penetrometer resistance reached 0.69 MPa.
Soil tillage can originate compacted layers in the soil subsurface. This compaction reduces root growth, plant development and eventually soybean yields. This study examined the effects of subsurface compaction on soybean root growth and morphology as related to plant growth and mineral nutrition. Soybean plants cv. Primavera were grown up to 37 days from seedling emergence in pots where a compacted layer was set at the 15.0 to 18.5 cm depth. This layer was compacted to bulk densities of 1.03, 1.25, 1.48 and 1.72 g/cm³, corresponding to cone penetrometer resistances of 0.05, 3.0, 7.5 and 2.0 MPa, respectively. The soil was a Dark Red Latosol (Haplortox), sandy loam, with 80% of sand and 16% of clay. Soil subsurface compaction led to a higher concentration of roots in the surface layer of the pots, without significant effects on plant canopy growth and nutrition. In the presence of a compacted layer the roots were shorter, but nutrient absorption/cm of root was higher. There was some restriction to root growth in the bulk density of 1.25 g/cm³, but there was necessary a bulk density of 1.72 g/cm³ to inhibit completely the root growth. Soybean root growth was decreased by 50% when the penetrometer resistance reached 0.69 MPa.
Descrição
Palavras-chave
Glycine max L. Merrill, resistência à penetração, impedância do solo, crescimento de raízes, Glycine max L. Merrill, penetrometer resistance, soil impedance, root growth
Como citar
Bragantia. Instituto Agronômico de Campinas, v. 53, n. 2, p. 259-266, 1994.