Edmilson Evangelista da Silva

Survival of endophytic diazotrophic bacteria in soil under different moisture levels

Neste trabalho foi avaliado o efeito da umidade do solo na sobrevivencia de tres especies de bacterias diazotroficas (Azospirillum amazonense, Gluconacetobacter diazotrophicus e Azospirillum brasilense). O teor de umidade apresentou pouca influencia na sobrevivencia de A. brasilense, considerada uma especie cosmopolita, enquanto A. amazonense e G. diazotrophicus, consideradas endofiticas, aumentaram o periodo de culturabilidade na presenca de umidade no solo. Os resultados demonstram que o teor de umidade do solo possui maior influencia nas especies endofiticas, em comparacao as especies associativas.

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.

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.

Fertilizantes de leguminosas como fontes alternativas de nitrogênio para produção orgânica de alface

O objetivo deste trabalho foi avaliar o potencial de dois fertilizantes de leguminosas - produtos derivados do corte, desidratacao e moagem da biomassa aerea das leguminosas mucuna-cinza (Mucuna pruriens) e gliricidia (Gliricidia sepium) - como fontes alternativas de nitrogenio (N) para a producao orgânica de alface (Lactuca sativa cv. Vera), e a influencia dessas adubacoes sobre a vida util pos-colheita da hortalica, em condicoes de laboratorio. Esses fertilizantes foram empregados em cobertura e comparados com cama-de-aviario industrial, assegurando-se doses equivalentes de N total. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos e quatro repeticoes: T1: adubacao pre-plantio, com termofosfato silico-magnesiano + sulfato de potassio; T2: T1 + esterco bovino, em pre-plantio; T3: T2 + fertilizante de mucuna-cinza, em cobertura; T4: T2 + fertilizante de gliricidia, em cobertura; T5: T2 + cama-de-aviario em cobertura. Nao houve diferenca entre os fertilizantes de ambas as especies de leguminosas e a cama-de-aviario, quanto a produtividade, teor de N, padrao comercial e periodo de vida util pos-colheita das alfaces, o que indica potencial de uso desses fertilizantes como fontes de N para sistemas orgânicos de producao de hortalicas.