RESUMO: A presença de camada compactada próxima à superfície do solo e a variabilidade das propriedades químicas do solo podem afetar o rendimento de grão de soja. Com o trabalho, objetivou-se avaliar a influência de sistemas de preparo do solo e de semeadura e de locais de cultivo (áreas de corte e aterro) no rendimento dessa cultura. O experimento foi realizado na área experimental de várzea da Universidade Federal de Santa Maria, nas safras 2013/14 e 2014/15. O delineamento foi blocos ao acaso, com quatro repetições. Os tratamentos foram arranjados em parcelas subdivididas. As parcelas principais foram: área de corte (A1) e área de aterro (A2). As subparcelas foram os tipos de preparo do solo e de semeadura: com escarificação do solo e semeadura utilizando disco duplo na semeadora (D1); sem escarificação do solo e semeadura utilizando haste sulcadora na semeadora (D2); sem escarificação do solo e semeadura utilizando disco duplo na semeadora (D3). A cultivar utilizada foi a BMX Tornado. O tratamento com escarificação e haste sulcadora reduziu a resistência do solo à penetração e proporcionou maior teor de Mg e S no tecido foliar na safra 2013/14; e de N, P, K, Ca, Mg e S, em 2014/15. Esse tipo de preparo de solo possibilita maior rendimento de grão de soja sem diferenças entre as áreas de corte e de aterro.
Resumo: O objetivo deste trabalho foi avaliar o efeito de sistemas de plantio e irrigação suplementar em faixas sobre o rendimento de grãos de soja, em áreas com presença de camada compactada próxima à superfície do solo. Dois experimentos foram realizados em blocos ao acaso, em faixas, com quatro repetições, no Estado do Rio Grande do Sul. O experimento 1 foi realizado em Santa Maria, correspondente às safras de 2013/2014 e 2014/2015; e o experimento 2, em Formigueiro, na safra 2013/2014. Os tratamentos consistiram dos fatores A e D. O fator A considerou os seguintes sistemas de plantio: A1, semeadura com discos duplos desencontrados; A2, semeadura com disco ondulado de 12 ondas; A3, semeadura com haste sulcadora; A4, semeadura com haste sulcadora e um mecanismo de acomodação do solo; A5, semeadura em microcamalhão; e A6, escarificação do solo e semeadura com disco duplo desencontrado. O fator D consistiu de tratamentos com ou sem irrigação. Na safra 2014/2015, alterou-se o fator A4 por haste desencontrada a 5 cm da linha de semeadura. O experimento 2 constituiu-se apenas do fator A do experimento 1, sem o tratamento microcamalhão. Os sistemas com escarificação do solo e haste sulcadora são os que proporcionam maior rendimento de grãos. A irrigação realizada em condições de umidade do solo abaixo de 60% da capacidade de campo aumenta o rendimento de grãos.
ABSTRACT:A compacted subsurface soil layer can be a limiting factor for soybean growing, reducing soybean yield. The aim of this study was to evaluate the effect of different tillage systems on the physical properties of two Albaqualf soils of the Central Plains region in the state of Rio Grande do Sul in southern Brazil. Two experiments were conducted: one in Santa Maria, RS, during the 2013/14 and 2014/15 crop seasons, and another in Formigueiro, RS, during the 2013/14 crop season. A randomized block experimental design with four replications was used. The treatments were: sowing using an offset double disc (T1); sowing using a fluted coulter disc (wavy disc with 12 waves) (T2); sowing with a knife runner opener (T3); sowing with a knife runner opener + press wheel mechanism for ground levelling (T4); sowing using a furrow opener upon a raised bed (T5); and chisel plough + sowing using an offset double-disc (T6). In the 2014/15 growing season, the T4 factor was changed using a knife runner opener 0.05 m from the planting row. A smaller reduction in the compacted subsurface soil layer was observed for both T1 and T2, which exhibited high soil bulk density values for the 2013/14 and 2014/15 crop seasons. Furthermore, T3, T5 and T6 led to a reduction in bulk density, and increasing total porosity and macroporosity in the soil, which consequently increased water infiltration, water storage capacity, and crop yield in areas with the presence of a compacted subsurface soil layer.
How to cite OLIVEIRA, L.M. de; MARCHESAN, E.; DAVID, R. de; WERLE, I.S.; ARAMBURU, B.B.; DONATO, G.; SILVA, A.L da; COSTA, I.F.D. da. Occurrence of rice blast on and grain quality of irrigated rice fertilized with nitrogen and silicates.Abstract -The objective of this work was to evaluate the effects of fertilization with nitrogen topdressing and silicates, as well as of the use of fungicides, on the occurrence of rice blast on panicles, milling yield, and whole grains, vitreous grains, and chalky kernels in a flood-irrigated rice cultivar sensitive to the disease. Two experiments were conducted in a randomized complete block design, in a 4×4×2 factorial arrangement, with four replicates: in experiment 1, four doses of nitrogen × four doses of calcium and magnesium silicate on soil × with and without fungicides; and, in experiment 2, four doses of nitrogen × four doses of potassium silicate applied on leaves x with and without fungicides. At the doses above 60 kg ha -1 nitrogen without fungicides, there was an increase of rice blast severity on panicles, a decrease in the percentage of whole and vitreous grains, and an increase in chalky kernels and chalky area. The greatest effects of silicates occurred without fungicides. Fungicide use reduced the severity of rice blast on panicles. Milling yield ranged from 60 to 70% in both experiments. The control of rice blast with fungicides maintains high rice grain quality, milling yield, and percentages of whole and vitreous grains.
The intensive use of plant protection products in rice paddy fields ( Oryza sativa L.) has caused concern about the environmental impact on communities of non-target organisms that are natural inhabitants in these agroecosystems. The purpose of this review is to analyze the data currently available in the literature about some important fungicides and insecticides (such as trifloxystrobin, tebuconazole, tricyclazole, lambda-cyhalothrin, and thiamethoxam), which are currently used to control pests and diseases in rice paddy fields, as well as their effects on the community of non-target aquatic organisms.
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