Pedro Marques da Silveira

Efeitos do sistema de preparo na compactação do solo, disponibilidade hídrica e comportamento do feijoeiro

Neste trabalho foram avaliados os efeitos dos sistemas de preparo com arado de aiveca, com grade aradora e plantio direto, na compactacao do solo, na disponibilidade de agua, no desenvolvimento radicular e na produtividade do feijoeiro (Phaseolus vulgaris L.). A area experimental consistiu de um Latossolo Vermelho-Escuro, sob irrigacao via pivo central, o que possibilitou dois cultivos ao ano. O preparo com arado propiciou menores valores de resistencia a penetracao, ao longo do perfil do solo. O preparo com grade condicionou uma camada mais compacta entre 10 e 24 cm de profundidade e, em plantio direto, houve maior compactacao ate 15 - 22 cm. A distribuicao do sistema radicular, em profundidade, foi mais uniforme no preparo com arado. No preparo com grade houve concentracao das raizes na camada de 0-10 cm de profundidade e, em plantio direto, a concentracao ocorreu ate 20 cm. Sob irrigacao, a menor resistencia do solo a penetracao e a melhor distribuicao do sistema radicular, no preparo com arado, nao possibilitou ao feijoeiro obter maior produtividade em relacao aos outros sistemas de preparo. A maior produtividade observada no plantio direto deveu-se, entre outros fatores, aos menores valores e a menor variacao ao longo do ciclo da tensao matricial da agua no solo, em comparacao aos demais sistemas de preparo do solo.

Cover crops and physical quality of a Latosol under no-tillage

The objective of this study was to determine the effect of cover crop mulches on the physical quality of a distrophic Red Latosol (Oxisol) under no-tillage. The experiment was carried out under center pivot at Embrapa Rice & Beans, in Santo Antonio de Goias, GO, in a randomized block design, with eight replications. The treatments consisted of eight cover crops: Brachiaria brizantha; corn associated with B. brizantha; pigeon pea; millet; Panicum maximum; sorghum; Stylosanthes guianensis; and Crotalaria juncea. The first seven crops had been cultivated in summer season since December 2001 and C. juncea since November 2003. In the winter season, after cover crop desiccation, irrigated common bean crop under no-tillage was planted. In February 2006, soil organic matter content, some soil physical attributes, and soil physical quality measured by S index were determined. Cover crops, especially grasses, favored soil aggregation at the surface layer. Soil cultivation modified its structure in comparison to native forest, increasing bulk density and reducing macroporosity, total porosity, and soil physical quality. Among the cover crops, pigeon pea, C. juncea, and corn associated with B. brizantha were those that maintained soil surface layer with good physical quality.

Macrofauna edáfica associada a plantas de cobertura em plantio direto em um Latossolo Vermelho do Cerrado

The objective of this work was to characterize soil fauna groups and to evaluate the effects of cover crops under no-tillage system, in a Cerrado Oxisol, in two evaluation periods. The cover crops: Crotalaria juncea, Cajanus cajan, Stylosanthes guianensis, Brachiaria brizantha, Brachiaria brizantha/Zea mays association, Pennisetum glaucum, Panicum maximum and Sorghum bicolor were cultivated from November to April of each year. Common bean was sown every September under centre pivot irrigation. The area of each plot was 60 m 2 . Soil monoliths (25x25 cm) were taken randomly from each plot, at 0-10 cm and 10-20 cm dephs, in April and September, 2005, and macrofauna was hand sorted. Identified groups in decreasing order of total density are: Formicidae, Oligochaeta, Dermaptera, Coleoptera, Hemiptera, Miriapoda, Isoptera, Araneae, Lepidoptera, Blattodea and Diptera larvae. Crotalaria juncea showed the highest macrofauna density, followed by B. brizantha, B. brizantha/Zea mays association, Sorghum bicolor, Stylosanthes guianensis, Cajanus cajans, Pennisetum. glaucum, Panicum maximum. The use of cover species in no-tillage system, associated with irrigation, promotes soil colonization by macrofauna.

Adubação nitrogenada no feijoeiro cultivado sob plantio direto em sucessão de culturas

Resumo – O nitrogenio e um nutriente essencial ao feijoeiro e sua carencia e observada em quase todos os solos. O objetivo deste trabalho foi avaliar a resposta do feijoeiro irrigado por aspersao a adubacao nitrogenada em cobertura, num Latossolo Vermelho distrofico. O cultivo foi realizado em sistema pivo central, em condicoes de plantio direto com sucessao de diferentes culturas. Os tratamentos constituiram-se de sete culturas: braquiaria cv. Marandu, milho em consorcio com braquiaria, guandu, milheto, mombaca, sorgo granifero e estilosantes cv. Mineirao. Sobre as palhadas picadas das culturas, foi semeado o feijao cv. Perola e aplicados em cobertura 0, 30, 60 e 120 kg ha -1 de N (ureia). Houve efeito das palhadas sobre a produtividade de graos e as maiores produtividades alcancadas foram sobre as palhadas de milheto e do guandu. O feijoeiro responde a aplicacao de N em cobertura em todas as sucessoes, com resposta quadratica sobre o milheto e o guandu, e linear nas demais. Termos para indexacao: Phaseolus vulgaris, gramineas, leguminosas, nitrogenio, adubacao de cobertura. Nitrogen fertilization of common bean grown under no-tillage system after several cover crops

Atributos biológicos do solo sob influência da cobertura vegetal e do sistema de manejo

The objective of this work was to evaluate the effects of cover crops and direct and conventional tillage systems on soil biological attributes when cultivated with dry bean in winter under sprinkle irrigation. The experiment was conducted in Santo Antonio de Goias, GO, Brazil, in a clayey Rhodic Haplustox. Cover crops were cultivated annually in the summer since 2001, using Brachiaria brizantha, Cajanus cajan, Pennisetum glaucum, Panicum maximum, sorghum, Stylosanthes guianensis, brachiaria in association with corn, and native vegetation as reference. In 2005, 60 days after cutting the cover crops, BRS Valente bean cultivar, under irrigation, was cultivated. Sowing was performed on June 16, 2005 and the harvest on September 19, 2005. Soil samples were collected to a depth of 0-10 cm, in November 2004 (before cover crops planting), June 2005 (before dry bean planting) and July 2005 (at dry bean flowering). Evaluations of basal respiration, carbon and nitrogen of microbial biomass, microbial/organic carbon ratio, microbial/total nitrogen ratio and metabolic quotient were performed. Soil biological attributes were influenced by cover crops, soil management and sampling time.

Eficiência de uso de nitrogênio em cobertura pelo feijoeiro irrigado

Entre as tecnicas de manejo necessarias para atingir alto potencial produtivo nos sistemas agricolas irrigados, esta a adubacao nitrogenada. O objetivo deste trabalho foi avaliar os efeitos de doses de nitrogenio aplicadas em cobertura sobre a fitomassa e a eficiencia de uso do nutriente pela cultivar BRS Horizonte de feijoeiro. O experimento foi conduzido na Embrapa Arroz e Feijao, em um Latossolo Vermelho distrofico, em delineamento experimental de blocos ao acaso, com quatro repeticoes e cinco doses de nitrogenio, 0, 30, 60, 120 e 240 kg ha-1, na forma de ureia, aplicadas em cobertura metade aos dez dias apos a emergencia (DAE) e a outra metade aos 17 DAE. A fitomassa no florescimento do feijoeiro relacionou-se linearmente com as doses de N aplicadas em cobertura, ao passo que a fitomassa na colheita apresentou resposta quadratica. As relacoes entre o indice de colheita de graos e o indice de colheita de N com as doses de N foram quadraticas e os indices maximos foram estimados com a dose de 140 kg ha-1 de N. A eficiencia de uso de nitrogenio pelo feijoeiro variou com as doses de N aplicadas e com o tipo de eficiencia calculada, enquanto as eficiencias agronomica e fisiologica diminuiram com o incremento da dose.

Sistemas de cultivo, sucessões de culturas, densidade do solo e sobrevivência de patógenos de solo

The objective of this work was to evaluate the effect of cropping systems and crops cultivated previously to common beans (Phaseolus vulgaris L.) on soil density and soil populations of Rhizoctonia spp. and Fusarium spp. Previous crops included the following legumes: Cajanus cajan,Stylosanthes guianensis cv. Mineirao and Crotalaria spectabilis; and the following grasses: Pennisetum glaucum (cv. BN-2, millet), Sorghum bicolor (cv. BR 304), Panicum maximum cv. Mombaca, Brachiaria brizantha cv. Marandu and a consortium of corn (Zea mays) and B. brizantha. Previous crops were planted in Brazil summer seasons (wet) of 2002, 2003 e 2004, and bean crop (cv. BRS Valente) was planted in the correspondent subsequent winters (dry) of 2003, 2004 and 2005, irrigated by central pivot. Crop residues were incorporated to the soil, in conventional tillage, and kept on the surface, in no tillage management. In general, soil populations of Fusarium spp. and Rhizoctonia spp. were higher in no tillage cropping system. Higher populations of Rhizoctonia spp. were found in heavier soils. Legume crop residue increased soil populations of Rhizoctonia spp. and Fusarium spp. and, therefore, Leguminosae should be avoided as previous crops to common beans, in both cultivation systems. Generally, Gramineae previous crops are supressive to soil populations of Rhizoctonia spp. and Fusarium spp.The objective of this work was to evaluate the effect of cropping systems and crops cultivated previously to common beans (Phaseolus vulgaris L.) on soil density and soil populations of Rhizoctonia spp. and Fusarium spp. Previous crops included the following legumes: Cajanus cajan, Stylosanthes guianensis cv. Mineirao and Crotalaria spectabilis; and the following grasses: Pennisetum glaucum (cv. BN-2, millet), Sorghum bicolor (cv. BR 304), Panicum maximum cv. Mombaca, Brachiaria brizantha cv. Marandu and a consortium of corn (Zea mays) and B. brizantha. Previous crops were planted in Brazil summer seasons (wet) of 2002, 2003 e 2004, and bean crop (cv. BRS Valente) was planted in the correspondent subsequent winters (dry) of 2003, 2004 and 2005, irrigated by central pivot. Crop residues were incorporated to the soil, in conventional tillage, and kept on the surface, in no tillage management. In general, soil populations of Fusarium spp. and Rhizoctonia spp. were higher in no tillage cropping system. Higher populations of Rhizoctonia spp. were found in heavier soils. Legume crop residue increased soil populations of Rhizoctonia spp. and Fusarium spp. and, therefore, Leguminosae should be avoided as previous crops to common beans, in both cultivation systems. Generally, Gramineae previous crops are supressive to soil populations of Rhizoctonia spp. and Fusarium spp.

Adubação nitrogenada em arroz sob irrigação suplementar por aspersão

The objective of this study was to determine adequate N level for modern upland rice (Oryza sativa L.) cultivars sown at 0.20 m row spacing under supplemental sprinkler irrigation. The effects of N levels (0, 40, 80, 120, and 160 kg of N/ha) on the yield of one cultivar (Maravilha) and three favourable upland rice lines (CNA7127, CNA7730, and CT7/15) were studied during three crop seasons, in Santo Antonio de Goias, GO, Brazil, in a Dark Red Latosol. According to regression model used, the maximum rice grain yield was 5,523 kg/ha, obtained with 112.9 kg of N/ha. Considering the prices of N (R

Adubação nitrogenada na produtividade, leitura SPAD e teor de nitrogênio em folhas de feijoeiro

1.20) and rice (R

Adubação nitrogenada em cobertura na cultura do trigo em sistema de plantio direto após diferentes culturas.

0.20) practiced in Goiânia, on June/97, the economical N level was 87.3 kg/ha.