RESUMO
Integrating plant density and nitrogen (N) management is a strategy for improving corn yields, especially for off-season corn production in the tropics. This study tested the hypothesis that increasing plant densities and N rates promotes yield gains for off-season corn production in high-yielding environments. The aim of the study was to investigate the yield performances of two hybrid versions (DKB PRO and DKB PRO3) submitted to three plant densities (55,000; 65,000 and 75,000 plants ha−1) and four N rates (control, 60, 120 and 180 kg ha−1 N). Field trials were undertaken at Uberlândia-MG (site1 and 2) and Pedro Afonso-TO (site 3), Brazil from which data on corn yield parameters were collected and analyzed. Multivariate analysis separated the three trial areas into two groups, presenting high (sites 1 and 2) and low yields (site 3), which were related to weather conditions. There was no influence of a hybrid version or plant densities on crop yields at site 1 or 2. In contrast, there was a positive response to increasing plant densities and the use of DKB PRO3 at site 3. A significant response to N was observed at sites 2 and 3, following a plateau model. Our results suggest that N application rates and plant densities do have the potential to increase off-season corn yields in low yielding environments.(AU)
RESUMO
Integrating plant density and nitrogen (N) management is a strategy for improving corn yields, especially for off-season corn production in the tropics. This study tested the hypothesis that increasing plant densities and N rates promotes yield gains for off-season corn production in high-yielding environments. The aim of the study was to investigate the yield performances of two hybrid versions (DKB PRO and DKB PRO3) submitted to three plant densities (55,000; 65,000 and 75,000 plants ha−1) and four N rates (control, 60, 120 and 180 kg ha−1 N). Field trials were undertaken at Uberlândia-MG (site1 and 2) and Pedro Afonso-TO (site 3), Brazil from which data on corn yield parameters were collected and analyzed. Multivariate analysis separated the three trial areas into two groups, presenting high (sites 1 and 2) and low yields (site 3), which were related to weather conditions. There was no influence of a hybrid version or plant densities on crop yields at site 1 or 2. In contrast, there was a positive response to increasing plant densities and the use of DKB PRO3 at site 3. A significant response to N was observed at sites 2 and 3, following a plateau model. Our results suggest that N application rates and plant densities do have the potential to increase off-season corn yields in low yielding environments.
RESUMO
As cinzas provenientes da queima de carvão mineral, seja in natura ou zeolitizada, possuem estrutura e características químicas semelhantes às zeólitas. Verificou-se a adição destes materiais à uréia nas proporções ureia:cinzas 100:10, 100:20, 100:50, 100:100 e um controle (somente ureia), em delineamento com blocos casualizados em solo arenoso e argiloso sem incorporação, avaliando as perdas de nitrogênio por volatilização de amônia e os parâmetros químicos de fertilidade do solo. As proporções 100:10 e 100:20 promoveram redução significativa de perdas por volatilização da amônia, porém somente no solo de textura arenosa. Não há diferença entre a cinza zeolitilizada e a cinza in natura visando à redução das perdas de N por volatilização de NH3 da ureia.
The structural and chemical characteristics of fly ash from coal-fired mineral and fly ash zeolitized are similar to those of zeolites. Urea was added with these materials in the proportions of urea: fly ashes of 100:10, 100:20, 100:50, 100:100, with a control containing just urea. These treatments were applied in soil surface and the experimental design was a randomized block with clay and sandy soil. Nitrogen losses by ammonia volatilization and the chemical characteristics of soil fertility were evaluated. In sandy soil there was reduction of ammonia volatilization for the proportions of 100:10 and 100:20, while fly ash zeolitized and fly ash had no difference.
RESUMO
As cinzas provenientes da queima de carvão mineral, seja in natura ou zeolitizada, possuem estrutura e características químicas semelhantes às zeólitas. Verificou-se a adição destes materiais à uréia nas proporções ureia:cinzas 100:10, 100:20, 100:50, 100:100 e um controle (somente ureia), em delineamento com blocos casualizados em solo arenoso e argiloso sem incorporação, avaliando as perdas de nitrogênio por volatilização de amônia e os parâmetros químicos de fertilidade do solo. As proporções 100:10 e 100:20 promoveram redução significativa de perdas por volatilização da amônia, porém somente no solo de textura arenosa. Não há diferença entre a cinza zeolitilizada e a cinza in natura visando à redução das perdas de N por volatilização de NH3 da ureia.
The structural and chemical characteristics of fly ash from coal-fired mineral and fly ash zeolitized are similar to those of zeolites. Urea was added with these materials in the proportions of urea: fly ashes of 100:10, 100:20, 100:50, 100:100, with a control containing just urea. These treatments were applied in soil surface and the experimental design was a randomized block with clay and sandy soil. Nitrogen losses by ammonia volatilization and the chemical characteristics of soil fertility were evaluated. In sandy soil there was reduction of ammonia volatilization for the proportions of 100:10 and 100:20, while fly ash zeolitized and fly ash had no difference.