Raul de Ld Ribeiro

Avaliação de coberturas mortas em cultura de alface sob manejo orgânico.

A cobertura morta do solo com leguminosas e gramineas e uma pratica cultural que traz beneficios aos sistemas de producao. Foi conduzido um experimento no municipio de Seropedica, estado do Rio de Janeiro, com o objetivo de avaliar o efeito de diferentes tipos de cobertura morta sobre a reinfestacao de ervas espontâneas e sobre o desempenho agronomico de alface, em cultivo orgânico. O delineamento experimental adotado foi blocos casualizados com quatro repeticoes e parcelas de oito plantas na area util. Os tratamentos foram: bagaco de cana-de-acucar (Saccharum sp.), bambu (Bambuza sp.), capim Cameroon (Penisetum purpureum), crotalaria (Crotalaria juncea), eritrina (Erythrina poeppigiana), gliricidia (Gliricidia sepium), guandu (Cajanus cajan), mucuna cinza (Mucuna pruriens) e controle (sem cobertura dos canteiros). Estimou-se a decomposicao in situ e a liberacao de nitrogenio de cada cobertura morta. Foram avaliados dois ciclos consecutivos de alface, cultivar Regina, na mesma area, visando a comparar o efeito residual das coberturas mortas. Observou-se maior acumulo de N nos residuos vegetais das leguminosas (maximo de 1.010 kg ha-1 com mucuna-cinza). Em relacao a decomposicao da cobertura morta, avaliada na colheita do primeiro ciclo de alface (35 dias apos o transplante), as leguminosas apresentaram percentuais inferiores aos das gramineas de massa seca e N remanescentes. A reinfestacao dos canteiros pelas ervas espontâneas nao diferiu significativamente entre coberturas mortas, variando entre 31 e 58 plantas m-2, mas a reducao da densidade populacional da vegetacao reinfestante chegou a 83% em comparacao ao tratamento controle. Em ambos os ciclos de cultivo da alface, a massa fresca (de 315,8 a 366,0 e de 202,9 a 225,0 g planta-1, respectivamente nos primeiro e segundo ciclos), o diâmetro da cabeca (de 30,8 a 31,7 e de 25,5 a 28,5 cm) e o teor de N (de 32,3 a 38,8 e de 28,0 a 30,3 g kg-1) foram superiores quando leguminosas foram utilizadas como cobertura morta.

The use of sunn hemp as green manure intercropped with taro

An experiment was carried out in Mage, Rio de Janeiro State, Brazil, to evaluate the performance of taro (Colocasia esculenta) intercropped with sunn hemp (Crotalaria juncea), used as green manure. A randomized blocks design with four replicates was used and the soil of the field plots was classified as Haplic Gleysol. Treatments consisted of taro (1) intercropped with unpruned sunn hemp, (2) intercropped with sunn hemp cut at soil level, (3) intercropped with sunn hemp pruned at its mid-height, and (4) in monoculture. The taro was planted in double rows spaced by 1.0 m. The planting furrows had a space of 0.5 m, with rhizomes placed at every 3.0 m. The experimental plot consisted of four 3.0 m rows and the useful area corresponded to the five central plants in each of the two central rows. The sunn hemp was sown in parallel lines in the spaces between the taro double rows, 120 days after planting the taro. When the sunn hemp was cut at soil level, an accumulation of 211 kg ha-1 of N was observed. Besides this, the sunn hemps biomass promoted the cycling of an average 17 kg ha-1 of P, 85 kg ha-1 of K, 151 kg ha-1 of Ca, and 27 kg ha-1 of Mg. Worth mentioning, it represented also a deposition of 6.85 Mg ha-1 of dry substance. Even when pruned at its mid-height, the sunn hemp still provided 60% of nutrients relatively to the treatment in which it was cut at soil level. In addition to the nutrient supply, the use of taro intercropped with sunn hemp cut at soil level or pruned at mid-height represented efficient alternatives for controlling the spontaneous vegetation and for reducing taro leaf burning by solar radiation, without compromising the yield of taro. In all intercropping systems, taro plants had a larger leaf area and were taller than plants in monoculture.

Desempenho do inhame (taro) em plantio direto e no consórcio com crotalária, sob manejo orgânico

An experiment was carried out in the upland region of Rio de Janeiro State, Brazil, to evaluate different planting systems on yam performance under organic management. A randomized blocks design was used with four replications, in a 2 x 2 factorial scheme comprising the treatments: soil tillage system (no-tillage or conventional) and cropping system (monoculture or intercropping with Crotalaria juncea). Intercropping with C. juncea (sun hemp) stimulated yam vegetative growth and reduced leaf blight caused by sun radiation. The weed population was reduced more effectively associating no-tillage and intercropping with sun hemp. None of the treatments affected yam yield, which was considered satisfactory indicating the potential of the organic management adopted.

Produção de cebola orgânica em função do uso de cobertura morta e torta de mamona

A cebola e uma hortalica consumida em grande quantidade e tem sua producao concentrada no âmbito da agricultura familiar, sendo responsavel pela geracao de emprego e renda para grande numero de produtores rurais que tem no cultivo desta especie sua unica fonte de renda. E crescente a demanda por tecnologias para producao de cebola adequadas a agricultura familiar, com enfase em tecnicas agroecologicas. Neste aspecto, destaca-se a utilizacao de coberturas mortas e adubos orgânicos. O objetivo deste trabalho foi avaliar o efeito de diferentes coberturas mortas, associados a doses crescentes de torta de mamona aplicadas em cobertura, na producao total e no diâmetro dos bulbos de cebola produzidos em sistema orgânico. Observou-se efeito significativo da cobertura morta na producao total e nas diferentes classes de diâmetro de bulbo. Nao foram observados efeitos significativos da adubacao com a torta de mamona e da interacao entre cobertura e adubacao com torta de mamona. O efeito benefico da cobertura morta na produtividade e na qualidade da cebola foi, provavelmente, decorrente da manutencao de maior umidade e da reducao da amplitude termica do solo.

Consórcio couve-coentro em cultivo orgânico e sua influência nas populações de joaninhas

O consorcio de culturas e comumente praticado na producao de hortalicas devido a diversos beneficios economicos. Em alguns casos, podem reduzir infestacoes de pragas por favorecer a conservacao dos inimigos naturais nos agroecossistemas. Avaliou-se a viabilidade agronomica do consorcio de couve e coentro, sob manejo orgânico, com base em parâmetros fitotecnicos, alem de sua influencia sobre populacoes de joaninhas (Coleoptera: Coccinellidae), na comparacao com os respectivos cultivos solteiros. O coentro, representando a cultura secundaria, foi utilizado com a finalidade de fornecer recursos para as joaninhas. O estudo foi realizado em area do Sistema Integrado de Producao Agroecologica em Seropedica-RJ. O experimento consistiu dos consorcios: 1) couve consorciada com coentro, cujas quatro linhas de plantas foram colhidas na fase vegetativa (consorcio I), e 2) couve consorciada com coentro, cujas plantas das duas linhas internas (proximas a linha da couve) foram colhidas na fase vegetativa e as duas linhas externas foram cortadas apos floracao (consorcio II). Em ambos consorcios foram avaliados os parâmetros fitotecnicos da couve e do coentro na fase vegetativa (padrao comercial), enquanto que no consorcio II, tambem se avaliou as populacoes de joaninhas, por meio de coletas semanais de adultos, em comparacao com a couve em cultivo solteiro. O delineamento experimental foi em blocos ao acaso com quatro repeticoes. O coentro nao interferiu na produtividade da couve consorciada e sua introducao contribuiu positivamente para a abundância e diversidade de especies de joaninhas. O indice de equivalencia de area para o consorcio I, com referencia aos rendimentos de biomassa aerea fresca, foi superior em 92% em relacao ao cultivo solteiro. Este resultado demonstra a viabilidade do consorcio I, no manejo orgânico adotado, para plantios de outono nas condicoes edafoclimaticas da Baixada Fluminense.

Crescimento e produtividade do inhame cultivado entre faixas de guandu em sistema orgânico

Growth and productivity of taro intercropped with pigeon pea hedgerows in organic system under different management was tested in Bom Jardim, upland region of Rio de Janeiro State, Brazil. A completely randomized block design was used with four replicates. The treatments consisted of unpruned hedgerows; hedgerows pruned with the biomass maintained on the soil surface; and hedgerows pruned with the biomass removed from the experimental area. The unpruned hedgerows system was shown to be advantageous by protecting taro leaves against sun burning and keeping the same productivity of the hedgerows pruned system. In addition, it represented an effective way to control weeds, reducing manual labor and costs of organic taro production in which herbicides are not allowed. The legume hedgerows pruned promoted a significant input of organic matter and nitrogen (6.58 t of dry biomass ha-1 and 159 kg of N ha-1) and the recycling of other nutrients, like 20 kg of P ha-1, 136 kg of K ha-1, 64 kg of Ca ha-1 and 16 kg of Mg ha-1.

Agronomic viability of onion and lettuce intercropped in the organic cultivation system

Three intercrops of onion (cv. Alfa Tropical) and lettuce (cv. Regina 2000) were compared, varying the time intervals between transplants of each one in the field. The experiment was made in a complete randomized block design with the treatments (replicated six times): monocrops of onion and of lettuce, and intercrops of the two vegetables keeping the same onion spacing arrangement, with lettuce transplanted on the same day, 15 days, and 30 days after onion. Lettuce seedlings were placed between onion rows in an alternating manner, thus corresponding to half of its monocrop population density. Except for the last treatment (lettuce 30 days after onion planting) the intercropping system was advantageous in terms of increased income by cultivated area unit. Introducing lettuce into the system did not decrease onion yield in marketable bulbs. In addition, lettuce growth was comparable to that of its monocrop. The land equivalent ratio values confirmed the viability of intercropping onion and lettuce. Besides the adequate agronomic performance, the system leads to more efficiency of inputs and hand labor utilization under the organic management adopted.

Cultivo agroecológico de berinjeleira sob doses de adubação orgânica em coberturas vivas perenes

Agroecological cultivation of eggplant under different doses of organic fertilization using perennial species as cover crops Agronomic performance of eggplant was evaluated under organic management, comparing perennial grass and legume species as cover crops. The trial was carried out in Seropedica, Rio de Janeiro state, Brazil, using a randomized block design with a split plot arrangement and three replications. The evaluated treatments in the plots were forage peanut (Arachis pintoi) as cover crop, Bahia grass (Paspalum notatum) as cover crop, and conventional soil tillage (control). Split plot treatments were represented by increasing dosages of poultry litter, corresponding to 120, 240, 480, and 720 g plant -1 , which were partitioned through the eggplant cycle. The viability of forage peanut used as living mulch for eggplants was evidenced by the fact that its results did not differ statistically from conventional soil tillage for yield, number of fruits per hectare and average fruit weight of eggplant. The only exception is related to the use of forage peanut associated to the greatest dosis of organic fertilizer (720 g plant -1 ),