Benjamin Dias Osório Filho

Resposta de culturas à aplicação de enxofre e a teores de sulfato num solo de textura arenosa sob plantio direto

The total sulfur amount is lower in soils with low contents of clay and organic matter, and the aplications of limestone and fosfate fertilizers on the surface in no-tillage have reduced the sulfur disponibility through plants on the superficial layer of the soil. This study was carried out to evaluate the sulphate dynamic and the crop responses to S-SO4-2 application. The experiment was carried out at field using a sandy surface soil (Tipic Hapludult), and was a trifactorial with complete randomized blocks and four replications. Four S-SO4-2 levels (0, 15, 20 and 60kg ha-1) were applied at the principal plots; two crop rotations at the sub-plots (rapeseed/maize-crotalaria/wheat and soybean/canola/maize-mucuna beans); and the immediate and residual effect was studied at the sub subplot. Soil samples were collected before and after every crop and analyzed for S-SO4-2. The dry matter and crops yield and S-SO4-2 absorbed by plants were also evaluated. The results showed that rapeseed and maize responded to sulfur application. Soybean, canola and wheat do not respond to sulfur application.

Deposição do enxofre atmosférico no solo pelas precipitações pluviais e respostas de culturas à adubação sulfatada em sistema plantio direto

Some factors, such as atmospheric sulphur deposition by rain, may mask the crops response to fertilizers containing sulphur. This experiment was carried out to study (a) crop yields response to sulphur, and (b) sulphur deposition by rain. An experiment was installed in 2002 Winter, and cultivated to three crops sequences until December 2003, with sulfate rate of 0, 15, 30, and 60kg ha-1 for the first crop, 1/3 rates for the second crop and nil on the third. From May 2004 to October 2005, it was cultivated two new cultures in each crops system (black oat / bean / wheat and black oat / soybean / colza). The same sulfate rates applied in 2002 were again applied to second and third crops. The atmospheric sulphur deposition was evaluated by sampling all rain events from September 2004 to November 2005. Only bean responded to sulfate application. No response observed to other crop yields may be attributed to the sulphur atmospheric deposition and organic matter mineralization. The sulphur atmospheric deposition was 3.2kg ha-1 year-1 which is equivalent to almost 10kg ha-1 year-1 of sulfate.

Resposta à aplicação e recuperação de enxofre em cultivos de casa de vegetação em solos com diferentes teores de argila e matéria orgânica

The sulfur (S) dynamic and availability is less studied than others nutrients, even though S is an essential nutrient for crops production. This study was carried out to evaluate the crop responses to S-SO4-2 application in different soils and to study S recuperation by balancing it in soil and plants. The study was composed by a greenhouse experiment with six successive crops (canola, soybean, black bean, sesame, clover and wheat) using four soils and four S-SO4-2 levels (0, 5, 10 and 20mg kg-1) to evaluate immediate and residual effect of S-SO4-2 application. Soil samples were taken from 0-10 cm layer before and after each crop and analyzed for S-SO4-2. It was evaluate the dry matter production and S-SO4-2 absorbed by plants. Only canola responded to sulphur application. Soybean, black bean, sesame, clover and wheat did not response to sulfur application. There was not observed correlation between soil S-SO4-2 available in 10cm topsoil and crop yields. Soils with different clay and organic matter content showed similar behavior of crop response to sulfur application. The increase of S-SO4-2 availability with fertilization was greater in soils with more clay content.

Interação entre isolados de rizóbios e genótipos de tomateiro (Solanum lycopersicum)

Com o melhoramento vegetal, as plantas de tomateiro (Solanum lycopersicum) sao selecionadas com vistas a expressar o maximo do seu rendimento, tornando-se mais exigentes em fertilizantes e agrotoxicos. Na busca por sistemas mais sustentaveis de producao, necessita-se entender melhor as interacoes entre plantas e microrganismos promotores de crescimento. Estes podem ser utilizados como insumos biologicos, no entanto, sua eficiencia pode depender da interacao entre os genotipos dos organismos envolvidos. Dentre os microrganismos promotores de crescimento, estao os rizobios, que realizam a fixacao biologica de nitrogenio quando associados simbioticamente com leguminosas, que tambem podem estimular o crescimento de outras familias botânicas por outros mecanismos. Assim, o objetivo desta pesquisa foi avaliar a producao de diferentes genotipos de tomateiros quando inoculados com quatro isolados de rizobios. Foi realizado um experimento a campo, bifatorial, com delineamento experimental em blocos casualizados, com tres repeticoes. Cada bloco continha 15 unidades experimentais com oito plantas inoculadas com meio de cultura contendo rizobios. Foram utilizadas duas variedades crioulas e uma cultivar hibrida, inoculadas com os isolados UFRGS-VP16, UFRGS-Lc336, UFRGS-Lc348 e SEMIA-3007. Os frutos foram colhidos no comeco da maturacao, pesados e medidos. Os dados foram submetidos a analise de variância e teste Dunnett. As cultivares Cereja e Rosa, ambas crioulas, tiveram aumento de producao com a inoculacao com rizobios, enquanto a variedade Serato, hibrida, nao obteve incremento de producao com essa pratica.