Alexandre Tavares da Rocha

Produtividade, eficiência de uso da água e qualidade tecnológica de cana‑de‑açúcar submetida a diferentes regimes hídricos

O objetivo deste trabalho foi avaliar a produtividade de colmos e de acucar, a eficiencia de uso da agua e os atributos tecnologicos de cinco variedades de cana-de-acucar de maturacao precoce e seis de maturacao media a tardia, submetidas ao regime de sequeiro (1.141,4 mm) e a irrigacao plena (1.396,6 mm). Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repeticoes. A produtividade de colmos das variedades RB92579, RB72454 e SP81-3250 apresentou ganhos superiores a 180%, com uso da irrigacao. A irrigacao promoveu aumentos na produtividade de acucar superiores a 200%, nas variedades RB92579 e RB943365. A irrigacao plena proporcionou maior eficiencia de uso da agua, com producao media de 70,2 kg ha-1 mm-1 de colmos a mais em comparacao ao regime de sequeiro. Com excecao das variedades RB72454, RB763710 e RB943365, nao houve diferenca nos atributos tecnologicos entre a irrigacao plena e o regime de sequeiro. As variedades RB92579 e SP81-3250 de maturacao media a tardia se destacam quanto a produtividade de colmos e de acucar e a eficiencia de uso da agua, e sao recomendadas para estudos de resposta a irrigacao pela cana-de-acucar.

Características agroindustriais da cana-de-açúcar em função da adubação fosfatada, em solos de Pernambuco

The P recommendations in Northeastern Brazil are based on research carried out in the decades of 70 and 80, being necessary a modernization in this recommendation, to focus the maximum capacity of P adsorption. Therefore, this work aimed to evaluate agroindustrial sugarcane characteristics in soils in function of phosphate fertilization. Five experiments were carried out at Pernambuco State Forest Zone Region. The soils were: Argisoil Yellow distrocoeso (PAdx); Latosoil Yellow distrofic (LAd); Argisoil Yellow distrofic (PAd); Gleisoil haplic eutrofic (GXve); and Espodosoil carbic duripanic (ESKo). The treatments consisted of seven P doses, determined in function of the maximum adsorption capacity of P. The experimental design was a completely randomized block, with four replications. The sugarcane variety RB863129 was used in PAd, LAd, GXve and EKo soils and RB855536 on PAd soil. The P fertilization increased agricultural and industrial productivities. Total recoverable sugar (ATR) values were not affected by phosphate fertilizer, being more elevated in soils with higher maximum adsorption capacity of P.

Produção de capim elefante e movimentação de cátions em função de gesso mineral

The use of gypsum in context of exchangeable acidity in subsurface has provided the improvement of root environment, positive influence on crop yields. Therefore, the aim of this study was to evaluate the potential of the mined gypsum from the Araripe region in increasing the exchangeable Ca and also the reduction of exchangeable Al in subsurface, and increase in biomass production of varieties of elephant grass. The experiment was composed of three varieties of elephant grass, such as, Cameroon, Gramafante and Roxo in the presence and absence of mined gypsum through a factorial arrangement (3 x 2), with treatments arranged in 4 randomized blocks. The levels of Ca2+, S-SO42-, Al3+ and also its saturation were not affected by the application of mined gypsum in the soil subsurface layer. The application of mined gypsum reduced the pH of the soil subsurface layer. The growing of Cameroon variety promoted the increase in soil pH, reducing the Al saturation. The Cameroon and Gramafante had high dry matter yields, but only the Cameroon variety presented response to application of gypsum, which reached 33 Mg ha-1.

Extração e eficiência de uso de nutrientes em capim-elefante na presença de gesso

O cultivo de capim-elefante (Pennisetum purpureum Schum) na regiao do Polo Gesseiro do Araripe, localizada a oeste do Estado de Pernambuco, no Nordeste do Brasil, pode ser uma alternativa viavel de energia, em especial quando se realiza a correcao da fertilidade do solo. O objetivo deste trabalho foi avaliar o efeito do gesso no estado nutricional, na composicao mineral, na producao de biomassa e na extracao e eficiencia de nutrientes de variedades de capim-elefante na Chapada do Araripe, Estado de Pernambuco. Para isso, foram cultivadas tres variedades de capim-elefante - Cameroon, Gramafante e Roxo - na presenca e ausencia de gesso em blocos casualizados em arranjo fatorial (3 x 2), com quatro repeticoes. Os capins-elefante Cameroon e Gramafante apresentaram elevadas producoes de materia seca, porem apenas a variedade Cameroon mostrou resposta a aplicacao de gesso, tendo alcancado 33 Mg ha-1. O capim-elefante Gramafante foi mais eficiente no uso de Ca que as variedades Cameroon e Roxo.

Níveis críticos de fósforo em solos cultivados com cana-de-açúcar em Pernambuco

Critical levels of phosphorus in sugarcane soils of Pernambuco State, Brazil Physical, chemical and mineralogical properties of soils are not observed to estimate phosphorus (P) availability in Pernambuco, Brazil. The aim of this work was to determine phosphorus critical levels in distinct soils, using different chemical extractors, considering clay fraction content and quality , and to relate soil physical, chemical and mineralogical characteristics with P critical levels. The soils were classified like: Typic Haplustults; Typic Hapludox; Typic Hapludults; Typic Hydraquents and Typic Haplohumods. Treatments consisted of seven P doses, determined in function of P maximum adsorption capacity (PMAC). The experimental design was in randomized blocks, with four replicates. Samples of soil were collected at lots useful area. This sampling was made 30 days after the plantation and treatments application at 0,0-0,2 m depth. In these samples it was determined P content by the extractors Mehlich-1, Mehlich-3, Bray-1 and

Effects of different soil sampling instruments on assessing soil fertility in the caatinga area, Brazil

Vinicius Mendes de Azevedo, Duarte Barbosa, Fernando José Freire, Luis Carlos Marangon , Emídio Cantídio Almeida de Oliveira*, Alexandre Tavares da Rocha, Alexandre Campelo de Oliveira and Marcos Ribeiro da Silva Vieira Departamento de Agronomia, Universidade Federal Rural de Pernambuco, CEP: 52171-900, Recife, PE, Brasil. Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco, CEP: 59909-460, Serra Talhada, PE, Brasil. Departamento de Ciência Florestal, Universidade Federal Rural de Pernambuco, CEP: 52171-900, Recife, PE, Brasil.

Adubação fosfatada para cana-de-açúcar em solos representativos para o cultivo da espécie no Nordeste brasileiro

The objective of this work was to evaluate P availability in representative soils for plant cane cultivation in the Brazilian Northeast region, and to establish a new P‑fertilizing recommendation for this crop in these soils. The study was done in five soil types, in Zona da Mata of Pernambuco: Argissolo Amarelo distrocoeso (Ultisol), Argissolo Amarelo distrofico (Ultisol), Latossolo Amarelo distrofico (Oxisol), Gleissolo Haplico eutrofico (Gleisol), and Espodossolo Humiluvico ortico (Spodosol). Seven P doses were evaluated for maximum P adsorption capacity of each soil (solution equilibrium phosphorus, P‑rem). Thirty days after soil fertilization, P contents in soils were determined with the extractors Mehlich‑1, Mehlich‑3, Bray‑1, and anion exchange resin. P critical levels were calculated for each soil and extractor. From P availability ranges, five fertility classes were defined for different clay contents in the soils: very low, low, medium, high, and very high. Mehlich‑1 and anion exchange resin are able extractors to adequately represent soil‑P availability for plant cane cultivation in the evaluated soils.