STRUCTURING POTENTIAL OF COVER CROPS IN A CLAYEY OXISOL AND THEIR EFFECT ON CRAMBE GRAIN YIELD AND OIL CONTENT

This study aimed to assess the potential of twelve cover crops in improving the structural state of the soil  evaluating soil bulk density and soil resistance to penetration and their effects on crambe grain yield and oil content. The experiment was conducted at the Experimental Center of Agricultural Engineering (NEEA), at the State University of West Paraná (UNIOESTE) - Cascavel - Paraná. The cover crops were named as treatments and consisted of twelve species, namely: Crotalaria juncea, Crotalaria spectabilis, Pigeon pea, Jack bean, Foxtail millet, Forage sorghum, Lablab beans, Guandu beans, Mucuna aterrimum, Mucuna Pruriens, Mucuna deeringiana, Mucuna aterrima, and a control treatment (fallow area). The experimental design used consisted of randomized blocks with four replications and plots measuring 5 x 5 m. When species were in full bloom in May 2010, they were managed by desiccation with non-selective herbicide and subsequent mowing in order to accelerate the  decomposition rate of their roots. In August 2011 we performed the planting of crambe for further analysis of its grain and oil yield. In January 2012 soil samples  were collected to evaluate soil bulk density by the volumetric ring method at depths of 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Soil resistance to penetration was determined using a penetrometer until 0.4 m deep. In order to determine crambe grain yield, crambe was collected in an area of 4 m2 in the central part of each plot. In ordet tor determe seed oil content it was used the Soxhlet method. The statistical analyzes for soil variables (soil penetration density and resistance) and plant (grain yield and oil yield) consisted of analysis of variance (ANOVA), with a comparison test of mean values. It was also performed linear regression analyzes between data concerning to grain yield and oil yield, as well as grain yield and bulk density. The species Crotalaria spectabilis and Mucuna aterrima provided a significant reduction in soil bulk density when compared to the fallow area, showing higher structuring potential than other species after the first year of use. Considering the structural state of the soil prior to the experiment, with bulk density values lower than 1.2 Mg m-3, there was no significant effect on soil structure by any of the coverage species used and there was also no beneficial effect on crambe grain yield and oil content

Long-term effects of cover crops on physical-hydric properties of compacted soil

The screening of cover crops is essential for improving the physical-hydric properties of compacted soils. This study aimed to evaluate the effects of mixed or single cover crops on improving the physical-hydric properties of compacted Oxisol. Species with tap-rooted and fibrous-rooted rooting patterns were evaluated. The species included pearl millet (Pennisetum americanum), pigeon pea (Cajanus cajan), sunn hemp (Crotalaria spectabilis), velvet bean (Mucuna pruriens), white oat (Avena sativa), black oat (Avena strigosa), rye (Secale cereale), black oat + forage turnip (Raphanus sativus), black oat + white lupin (Lupinus albus L.), and black oat + group pea (Pisum arvense L.). Mixing cover crops did not improve the physical properties of the soil. The tap-rooted pigeon pea effectively reduces bulk density and increases porosity and saturated hydraulic conductivity (Ksat) in compact soils. The selection of cover crops with characteristics that improve soil physical-hydric properties is crucial for compacted areas

Structuring potential of cover crops in a clayey oxisol and their effect on crambe grain yield and oil content

This study aimed to assess the potential of twelve cover crops in improving the structural state of the soil evaluating soil bulk density and soil resistance to penetration and their effects on crambe grain yield and oil content. The experiment was conducted at the Experimental Center of Agricultural Engineering (NEEA), at the State University of West Paraná (UNIOESTE) - Cascavel - Paraná. The cover crops were named as treatments and consisted of twelve species, namely: Crotalaria juncea, Crotalaria spectabilis, Pigeon pea, Jack bean, Foxtail millet, Forage sorghum, Lablab beans, Guandu beans, Mucuna aterrimum, Mucuna Pruriens, Mucuna deeringiana, Mucuna aterrima, and a control treatment (fallow area). The experimental design used consisted of randomized blocks with four replications and plots measuring 5 x 5 m. When species were in full bloom in May 2010, they were managed by desiccation with non-selective herbicide and subsequent mowing in order to accelerate the decomposition rate of their roots. In August 2011 we performed the planting of crambe for further analysis of its grain and oil yield. In January 2012 soil samples were collected to evaluate soil bulk density by the volumetric ring method at depths of 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Soil resistance to penetration was determined using a penetrometer until 0.4 m deep. In order to determine crambe grain yield, crambe was collected in an area of 4 m2 in the central part of each plot. In ordet tor determe seed oil content it was used the Soxhlet method. The statistical analyzes for soil variables (soil penetration density and resistance) and plant (grain yield and oil yield) consisted of analysis of variance (ANOVA), with a comparison test of mean values. It was also performed linear regression analyzes between data concerning to grain yield and oil yield, as well as grain yield and bulk density. The species Crotalaria spectabilis and Mucuna aterrima provided a significant reduction in soil bulk density when compared to the fallow area, showing higher structuring potential than other species after the first year of use. Considering the structural state of the soil prior to the experiment, with bulk density values lower than 1.2 Mg m-3, there was no significant effect on soil structure by any of the coverage species used and there was also no beneficial effect on crambe grain yield and oil content.Este trabalho teve por objetivo avaliar o potencial de doze espécies de cobertura na melhoria do estado estrutural, através de avaliações da densidade e resistência do solo à penetração e seus reflexos no rendimento de grãos e de óleo da cultura do crambe. O experimento foi realizado no Núcleo Experimental de Engenharia Agrícola (NEEA), da Universidade Estadual do Oeste do Paraná (UNIOESTE) - Cascavel - Paraná. As espécies recuperadoras foram denominadas tratamentos e consistiram de doze espécies, sendo elas: crotalaria juncea, crotalaria spectabilis, feijão guandú, feijão de porco, capim moha, sorgo forrageiro, feijão lab-lab, guandú anão, mucuna preta, mucuna cinza, mucuna anã e mucuna verde, além da testemunha (área de pousio). O delineamento experimental utilizado foi o de blocos ao acaso com 4 repetições e parcelas experimentais de 5x5 m. Quando as espécies se encontravam em pleno florescimento, em maio de 2010, foram manejadas via dessecação, com o uso de herbicida de ação total, com posterior roçada, de forma a acelerar a velocidade de decomposição de suas raízes. Em Agosto de 2011 realizou-se o plantio de crambe para posterior análise do seu rendimento de grãos e de óleo. Em Janeiro de 2012, realizaram-se as coletas de amostras de solo, para avaliações de densidade do solo (Ds) pelo método do anel volumétrico, nas profundidades de 0,0-0,1; 0,1-0,2 e 0,2- 0,3m. A resistência do solo à penetração (Rs) foi determinada através de um penetrômetro, até 0,4m de profundidade. Para determinação do rendimento de grãos, colheu-se na parte central de cada unidade experimental uma área de 4m2. Para a determinação do teor de óleo nas sementes, foi utilizado o método Soxhlet. As análises estatísticas para variáveis de solo (densidade e resistência do solo à penetração) e de planta (rendimento de grãos e de óleo) consistiram de análise de variância (ANOVA), com posterior teste de comparação de médias. Também foram realizadas análises de regressão linear entre os dados de rendimento de grãos e rendimento de óleo, rendimento de grãos e densidade do solo. As espécies Crotalaria Spectabilis e Mucuna verde apresentaram redução significativa de Ds em comparação à área de pousio, mostrando potencial estruturante superior às demais espécies após o primeiro ano de uso. Para o estado estrutural que o solo se encontrava, com valores de densidade inferiores a 1,2 Mg m-3, não houve efeito significativo sobre a estrutura do solo por nenhuma das espécies de cobertura utilizada, bem como não houve efeito benéfico sobre o rendimento de grãos e de óleo do crambe