Danielle Medina Rosa

Efeito alelopático de sabugueiro e capim-limão na germinação de picão-preto e soja

Agriculture has been suffering adaptations throughout time, from hard hand labor to the most advanced sowing and harvesting techniques. Invasive plants are a constant, diminishing productivity by competing for space, nutrients, and water. Therefore, farmers have adopted, on a large scale, the use of efficient synthetic chemicals, which are highly toxic to the environment, in order to control plant production. However, there are other alternative means to control those competitors: using allelochemicals present in some plants, such as medicinal ones. The objective of this paper is to analyze allelophatic properties of the medicinal plants Cymbopogon citratus (DC) Stapf. and Sambucus australis Cham. and Schltdl., and inhibit Bidens pilosa L. without interfering on Glycine max L. Merrill germination. The extracts were obtained by crushing 200 g of leaves and mixing them with 1 liter of distilled water. The seeds were kept in B.O.D. at a temperature of 25oC, with a photoperiod of 12 hours of light. Considering the conditions in which the experiment was performed, it was concluded that the warm liquid extract of Cymbopogon citratus restrained the germination of Bidens pilosa L. without interfering on the germination of soybean, whereas the warm liquid extract of Sambucus australis Cham. constrained soybean and Bidens pilosa L. germination. Thus, the use of Cymbopogon citratus (DC) Stapf. as a natural herbicide for Bidens pilosa L. is recommended.

Variation on the amount of winter cover crops residues on weeds incidence and soil seed bank during an agricultural year

This study analyzed possible interferences associated to the amount of crop residues produced by the black oats and the consortium of black oats, common vetch and forage turnip on weeds incidence and soil seed bank. It was a field trial with seven treatments and five replications. The cover crop was sown at throwing, cut at 100 days and residues were put on each respective plot, using a proportion of normal amount of produced straw, either its half and double. The heaviest weights were obtained from cover crop consortium and their application decreased weeds incidence in such area. The seeds bank and other analyzed parameters did not show statistical differences. According to these results, it was concluded that winter cover crop could be used in crops rotation with soybean.

Substâncias húmicas do solo cultivado com plantas de cobertura em rotação com milho e soja

A materia orgânica (MO), principalmente suas fracoes, e indicadora da qualidade do solo e, na agricultura, esta relacionada ao aporte de material vegetal por meio de cultivos. Neste contexto, a adocao de sistemas de manejo que aumentassem o fornecimento de MO, consequentemente, melhorariam a qualidade do solo. Assim, neste trabalho foram avaliadas alteracoes nos teores de MO e substâncias humicas em um LATOSSOLO VERMELHO Eutroferrico, cultivado com plantas de cobertura em rotacao com milho e soja. Em 2010, sob sistema de plantio direto, foram implantadas as plantas de cobertura mucuna ana (Mucuna deeringiana), feijao guandu anao (Cajanus cajan) e crotalaria juncea (Crotalaria juncea). Em 2011 foram implantadas as culturas do milho e as plantas de cobertura canola (Brassica napus), crambe (Crambe abyssinica) e nabo forrageiro (Raphanus sativus) e, em sequencia, a cultura da soja. O teor de MO e carbono das fracoes humicas foram determinados anteriormente a implantacao, apos o manejo da cobertura vegetal e apos a colheita dos cultivos. No ano agricola 2010/2011, apos manejo das plantas de cobertura leguminosas, observaram-se alteracoes na concentracao total de substâncias humicas do solo. Em 2011/2012 houve incremento no teor de carbono e alteracao no teor de acidos fulvicos. Dessa forma, as plantas de cobertura proporcionaram mais carbono na fracao acidos fulvicos que contribui com aspectos de fertilidade do solo (CTC). O manejo com as plantas de cobertura, leguminosas e brassicaceas, e o cultivo de milho e soja aumentaram teor de MOS em um curto periodo de tempo, sendo o manejo considerado adequado para as condicoes estudadas.

ATRIBUTOS FÍSICOS DO SOLO APÓS APLICAÇÃO DE ÁGUA RESIDUÁRIA DE SUINOCULTURA APLICADA EM COBERTURA NA CULTURA DO MILHO E CULTIVO SEQUENCIAL DE AVEIA PRETA

The rate of swine wastewater application (SW) in agricultural production could result in the replacement of chemical fertilizers. However, SW destroys soil physical properties by decreasing pore bulk, which negatively affects both crop yield and development. In this context, this study aimed at monitoring the influence of swine wastewater as a cover fertilizer in maize and black oats in sequence on soil physical properties. Five application rates (0, 100, 200, 300 and 537 mha 1 equivalent to 0, 11.2, 22.3, 33.5 and 60 kg ha N, respectively, based on the average nitrogen concentration in SW) were tested with four replications each. In the studied area, soil porosity, density, and water content, before maize sowing and at the end of the cycles of maize and black oats, were determined by the volumetric ring method. Data were submitted for regression analyses. There was a reduction in the macroporosity and total porosity of the soil when the SW application rate, before maize cultivation, was higher. The introduction of black oats helped to improve the physical quality of the soil and reduced the compaction of the surface layer from 0 to 15 cm and 100 to 300 m ha SW rates.

Soybean growth and yield after single tillage and species mixture of cover plants

A adequacao da cobertura vegetal a cultura agricola e ao manejo de solo e importante para obtencao de melhorias do sistema e, consequentemente, de maior produtividade. Nesse contexto, este estudo analisou a interferencia de restos vegetais de aveia preta (Avena strigosa Schreb) (AP) e coquetel de aveia preta, nabo forrageiro (Raphanus sativus L.) e ervilhaca-comum (Vicia sativa L.) (CO) no indice de velocidade de emergencia (IVE), velocidade de emergencia (VE) de plântulas, altura de plantas e produtividade da cultura da soja em intervalos diferenciados entre dessecacao da cobertura vegetal com glifosato 480 (3L ha-1) e semeadura da cultivar BRS 232. Parcelas de 5 m x 2,5 m, com 1 m de bordadura, receberam quatro tratamentos com cobertura AP, quatro para CO e uma testemunha para cada cobertura, ao acaso, com cinco repeticoes. A dessecacao foi nos intervalos de 1, 10, 20 e 30 dias anteriores a semeadura da soja. A colheita foi manual e a produtividade, ajustada para 13% de teor de agua. O delineamento experimental foi inteiramente casualizado, em esquema de parcelas subdivididas, teste de Scott e Knott a 5% de probabilidade. Pelos resultados obtidos pode-se recomendar a utilizacao do coquetel de coberturas na cultura da soja a fim de proporcionar emergencia de plântulas mais vigorosas. A semeadura da soja e recomendada a partir de 10 dias apos a dessecacao da cobertura vegetal.