Sistemas de cultivo e adubação nitrogenada em cobertura na cultura do milho
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Data
2020-07-09
Autores
Souza, Stefany Silva de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O consórcio do milho com braquiária e crotalária é estratégia de cultivo sustentável, capaz de gerar palhada para o sistema plantio direto (SPD) aliada à produtividade de grãos. Entretanto, dada a importância do nitrogênio para a cultura do milho, é necessário estabelecer o requerimento da cultura nos sistemas de consórcio em virtude da falta de informações. O objetivo com este trabalho foi avaliar, em dois experimentos, o desempenho agronômico em função de doses de nitrogênio em adubação de cobertura, para o milho em sistemas de cultivo exclusivo, consorciado com braquiária e com crotalária, assim como a palhada produzida nestes sistemas. Os experimentos foram instalados em uma área de Latossolo Vermelho eutroférrico de textura argilosa. O delineamento experimental foi em blocos casualizados em esquema de parcelas subdivididas, com quatro repetições. As parcelas foram compostas por três sistemas de cultivo, representados pelo milho exclusivo, milho consorciado com braquiária e milho consorciado com crotalária. As subparcelas foram constituídas por quatro doses de nitrogênio, sendo 0, 70, 140 e 210 kg ha-1, aplicadas em adubação de cobertura da cultura do milho, utilizando como fonte, ureia revestida com polímeros. As avaliações realizadas na cultura do milho foram: teor de nitrogênio foliar, altura de plantas, altura de inserção da espiga principal, diâmetro do colmo, comprimento de espiga, diâmetro de espiga, número de grãos por fileira, número de fileiras por espiga, número de grãos por espiga, massa de espiga, massa de mil grãos e produtividade de grãos. Calculou-se a eficiência agronômica. Em relação à palhada oriunda do ano agrícola 2017/2018 foram: produtividade, teor e acúmulo de nitrogênio. Em relação aos sistemas de cultivo, os resultados foram submetidos à análise de variância pelo teste F, e as médias agrupadas pelo teste Tukey. Realizou-se o estudo de regressão para efeitos de doses de N e a interação destas com os sistemas de cultivo. Utilizou-se a análise multivariada para análise das variáveis agronômicas do milho. A altura de inserção da espiga principal foi beneficiada pelo milho consorciado com a crotalária no experimento I e II. Enquanto a massa de espiga e a produtividade de grãos se destacaram no milho exclusivo no experimento I, as espigas foram mais compridas, porém não promoveram diferença de produtividade de grãos entre os sistemas de cultivo no experimento II. O teor de N foliar e a produtividade de grãos foram afetados pela interação entre sistemas de cultivo e doses de N em ambos experimentos, verificando-se maior necessidade de adubação para o milho em consórcio com a braquiária. Em relação às palhadas, os sistemas consorciados proporcionaram maiores produtividades e acúmulo de nitrogênio.
The maize intercropped with brachiaria and crotalaria is a sustainable cultivation strategy, able to generate straw for no-tillage system (NTS) along with grain yield. However, given the importance of the nitrogen for maize, it is necessary to establish the crop requirement in intercropped systems due to the lack of information. The objective of this work was to evaluate, in two experiments, the agronomic performance and the relative economic return, in function of nitrogen doses in topdressing fertilization, for maize in exclusive cultivation systems, intercropped with brachiaria and crotalaria, as well as the straw produced in these systems. The experiments were carried out in an area of Latossolo Vermelho Eutroférrico (Oxisol) with clay texture. The experimental design was in randomized blocks in a split-plot scheme, with four replications. The plots were composed of three cultivation systems represented by exclusive maize, maize intercropped with brachiaria and maize intercropped with crotalaria. The split-plots were four nitrogen doses, being 0, 70, 140 and 210 kg ha-1, applied in topdressing fertilization of maize, using polymer-coated urea. The assessments carried out in the maize crop were: leaf nitrogen content, plant height, height of main ear insertion, stem diameter, ear length, ear diameter, number of grains per row, number of row per ear, number of grains per ear, ear mass, thousand-grain weight and grain yield. Agronomic efficiency was calculated. Regarding the straw from the experiment I, were evaluated: yield, nitrogen content and nitrogen accumulation. Regarding the crop systems, the results were subjected to analysis of variance by F test, and the means were grouped by Tukey test. The doses and interaction between doses and crop systems were subjected to regression analysis. Multivariate analysis was used to analyse maize agronomic variables. The height of insertion of the main ear was benefited by corn intercropped with crotalaria in experiments I and II. While ear mass and grain yield stand out in exclusive corn in experiment I, ears were longer but did not promote a difference in grain yield between cultivation systems in experiment II. Leaf N content and grain yield were affected by the interaction between cultivation systems and N doses in both experiments, with a greater fertilization requirement for maize in intercropping with brachiaria. In relation to straw, the intercropped systems provided greater productivity and nitrogen accumulation.
The maize intercropped with brachiaria and crotalaria is a sustainable cultivation strategy, able to generate straw for no-tillage system (NTS) along with grain yield. However, given the importance of the nitrogen for maize, it is necessary to establish the crop requirement in intercropped systems due to the lack of information. The objective of this work was to evaluate, in two experiments, the agronomic performance and the relative economic return, in function of nitrogen doses in topdressing fertilization, for maize in exclusive cultivation systems, intercropped with brachiaria and crotalaria, as well as the straw produced in these systems. The experiments were carried out in an area of Latossolo Vermelho Eutroférrico (Oxisol) with clay texture. The experimental design was in randomized blocks in a split-plot scheme, with four replications. The plots were composed of three cultivation systems represented by exclusive maize, maize intercropped with brachiaria and maize intercropped with crotalaria. The split-plots were four nitrogen doses, being 0, 70, 140 and 210 kg ha-1, applied in topdressing fertilization of maize, using polymer-coated urea. The assessments carried out in the maize crop were: leaf nitrogen content, plant height, height of main ear insertion, stem diameter, ear length, ear diameter, number of grains per row, number of row per ear, number of grains per ear, ear mass, thousand-grain weight and grain yield. Agronomic efficiency was calculated. Regarding the straw from the experiment I, were evaluated: yield, nitrogen content and nitrogen accumulation. Regarding the crop systems, the results were subjected to analysis of variance by F test, and the means were grouped by Tukey test. The doses and interaction between doses and crop systems were subjected to regression analysis. Multivariate analysis was used to analyse maize agronomic variables. The height of insertion of the main ear was benefited by corn intercropped with crotalaria in experiments I and II. While ear mass and grain yield stand out in exclusive corn in experiment I, ears were longer but did not promote a difference in grain yield between cultivation systems in experiment II. Leaf N content and grain yield were affected by the interaction between cultivation systems and N doses in both experiments, with a greater fertilization requirement for maize in intercropping with brachiaria. In relation to straw, the intercropped systems provided greater productivity and nitrogen accumulation.
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Agricultura sustentável, Consórcios, Nitrogênio, Plantio Direto, Milho