Absorção de nitrogênio nativo do solo pelo milho sob plantio direto em sucessão a plantas de cobertura
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Data
2006-08-01
Autores
Silva, Edson Cabral da
Muraoka, Takashi
Buzetti, Salatiér [UNESP]
Veloso, Marcos Emanuel da Costa
Trivelin, Paulo César Ocheuze
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
O não revolvimento do solo com cultivo de adubos verdes na entressafra e o manejo da adubação nitrogenada alteram, geralmente, a dinâmica e a recuperação do N no sistema solo-planta. O objetivo deste trabalho foi avaliar a quantidade de N nativo do solo absorvido pelo milho em plantio direto, sob diferentes doses de N, em sucessão à crotalária (Crotalaria juncea), ao milheto (Pennisetum americanum) e à vegetação espontânea (pousio) em um Latossolo Vermelho no Cerrado. O estudo foi desenvolvido na fazenda experimental da Faculdade de Engenharia de Ilha Solteira-UNESP, Selvíria-MS, nos anos agrícolas 2001/02 e 2002/03. O delineamento experimental foi o de blocos casualizados com 15 tratamentos e quatro repetições, dispostos em esquema fatorial, 5 x 3, sendo cinco doses de N, na forma de uréia (0, 30, 80, 130 e 180 kg ha-1) e três sistemas de cobertura do solo (crotalária, milheto e o solo em pousio na entressafra). A quantidade de N nativo do solo absorvida pelo milho foi calculada pela diferença entre total de N acumulado na planta de milho, na época da maturação fisiológica, e o somatório do N proveniente da uréia, do milheto ou da crotalária determinados pelo método isotópico com 15N. O solo forneceu a maior quantidade de N para o milho, comparada à do fertilizante inorgânico conjuntamente à dos adubos verdes. As doses de N e os sistemas de cobertura do solo influenciaram significativamente a absorção de N nativo do solo pelo milho.
In untilled soils with green manure cultivation in during the dry season and the management of the nitrogen fertilization usually change the dynamics and the recovery of the nitrogen in the soil-plant system. The objective of this study was to evaluate the amount of native soil nitrogen absorbed by corn under no-tillage and submitted to different N rates in succession to sunnhemp (Crotalaria juncea), millet (Pennisetum americanum) and fallow in a Red Latosol in the Cerrado. The experiment was carried out on an Experimental Farm of the Faculty of Engineering, São Paulo State University (UNESP-Ilha Solteira), which is situated in Selvíria, state of Mato Grosso do Sul, Brazil, during the 2001/02 and 2002/03 growing seasons. The experiment was set up in a randomized complete block design, with 15 treatments and four replications in a 5 x 3 factorial scheme, which consisted of the combination of five urea-N rates (0, 30, 80, 130 and 180 kg ha-1 of N) and three preceding cover crops (sunnhemp, millet and fallow ground). The amount of soil native N absorbed by corn was calculated by the difference between the total N accumulated in the corn plant at physiologic maturation stage and the amount of N coming from urea, millet or sunnhemp as determined by the 15N isotopic method. The soil supplied greater N amounts to corn than the inorganic fertilizer and green manures combined. The N rates and cover crop systems significantly influenced the uptake of soil native nitrogen by corn plants.
In untilled soils with green manure cultivation in during the dry season and the management of the nitrogen fertilization usually change the dynamics and the recovery of the nitrogen in the soil-plant system. The objective of this study was to evaluate the amount of native soil nitrogen absorbed by corn under no-tillage and submitted to different N rates in succession to sunnhemp (Crotalaria juncea), millet (Pennisetum americanum) and fallow in a Red Latosol in the Cerrado. The experiment was carried out on an Experimental Farm of the Faculty of Engineering, São Paulo State University (UNESP-Ilha Solteira), which is situated in Selvíria, state of Mato Grosso do Sul, Brazil, during the 2001/02 and 2002/03 growing seasons. The experiment was set up in a randomized complete block design, with 15 treatments and four replications in a 5 x 3 factorial scheme, which consisted of the combination of five urea-N rates (0, 30, 80, 130 and 180 kg ha-1 of N) and three preceding cover crops (sunnhemp, millet and fallow ground). The amount of soil native N absorbed by corn was calculated by the difference between the total N accumulated in the corn plant at physiologic maturation stage and the amount of N coming from urea, millet or sunnhemp as determined by the 15N isotopic method. The soil supplied greater N amounts to corn than the inorganic fertilizer and green manures combined. The N rates and cover crop systems significantly influenced the uptake of soil native nitrogen by corn plants.
Descrição
Palavras-chave
Zea mays, mineralização, fertilizante 15N, pousio, adubo verde, matéria orgânica do solo, Zea mays, mineralization, fertilizer 15N, fallow, green manure, soil organic matter
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 30, n. 4, p. 723-732, 2006.