Data/hora: 20/06/2024 06:50:39

Biblioteca(s): | Embrapa Amazônia Ocidental; Embrapa Cerrados.
Data corrente: | 22/04/1999
Data da última atualização: | 05/11/1999
Autoria: | MELGAR, R. J.
Título: | Nitrogen utilization by annual crops in the central Amazon.
Ano de publicação: | 1989
Fonte/Imprenta: | Raleigh: North Carolina State University, 1989.
Páginas: | 239p.
Idioma: | Inglês
Notas: | Tese Doutorado.
Conteúdo: | Nitrogen fertilization experiments on corn (Zea mays L.) were conducted from 1984-1987 in an Tropofluvent and an Acrudox near Manaus, Brazil to define and compare fertilizer N responses. Maximum corn yield and N use efficiency was compared with that of rice (Oryza sativa L.). Maximum corn grain yields, ear-leaf N concentration and and optimum fertilizer N rates were low relative to other temperate and tropical environments. Optimum N rates in the Entisol increased progressively with subsequent cropping due to decreasing native N supply. Increasing acidity and Mg defficiency in the Oxisol affected N uptake in the Oxisol. Superior N supply at early growth stages in the Entisol resulted in higher leaf area and a superior and longer crop growth rate than in the Oxisol. Higher stalk biomass in the Entisol resulted in higher partitioning rates and contributed to superior grain yield relative to the Oxisol. Crop modeling suggests that warmer temperatures and lower solar radiation contribute 30% of the site differences. Nitrogen availability accounts for the remaining 70%. Maximum crop growth rates were lower than in other tropical locations. Nitrates remained longer in the Oxisol subsoil because of NO3- adsorption and lower microporosity than in the Entisol subsoil. During the wet season N leachin losses ranged from 15% to 40% in the Entisol and from 37% to 45% in the Oxisol. Highest yields and N recovery in the Oxisol were achieved with a single side-dress N application. Corn biomass, N uptake and time of cultivation correlated with soil inorganic N released during anaerobic incubation. Biomass production in the Entisol reached a plateau of 11t/ha-1 for both corn and favored upland rice. Rice required lower N rates for maximum yield because of higher N utilization efficiency and lower internal N requirement than corn. Under this non-limiting water and nutrient environment, low solar radiation and high temperature limit N responses and corn yields.
Palavras-Chave: | Amazon; Amazonas; Brasil; Fertilizer; Fertilizers application; Maize; Manaus; Plants; Zea may.
Thesagro: | Adubação; Adubo; Agricultura; Arroz; Cultivo Anual; Floresta Tropical Úmida; Milho; Nitrogênio; Oryza Sativa; Oxisol; Solo; Zea Mays.
Thesaurus Nal: | agriculture; Amazonia; annuals; Brazil; Ferralsols; nitrogen; nitrogen fertilizers; rice; soil; tropical rain forests.
Categoria do assunto: | --
Registro original: | Embrapa Cerrados (CPAC)

Exemplares:

CPAC - (15994-1) - ADD - TS - -- - T017/89 - MEL - T017/89 - DIS
CPAA - (3083-1) - ADD - TS - PP - T002/1989 -  - 1990.00001 - DIS