The effects of liming on the aggregate stability and erodibility of three Oxisols in Parana State, southern Brazil, were studied. Two soils from Londrina, one in a 10‐yr coffee (Coffea sp.) plantation (LC), and the other in a secondary mixed hardwood forest (LM), were compared with a third Oxisol from Cascavel, also under secondary mixed hardwood forest (CA), to give a range of surface organic‐C contents in the order CA > LM > LC. Lime was applied to replicated field plots at each site to neutralize 0, 25, 50, 100, 200, and 400% of total exchangeable acidity. Acid was also added to the Londrina soils to reduce initial soil pH to that of the Cascavel soil. Changes in aggregate stability, soil splash, and water erosion were measured. Lime application decreased the weight percentage of 2.0 to 4.0‐mm‐diam. aggregates and mean weight diameter (MWD) of aggregates in Cascavel soil, but had no effect on the other two soils. Liming decreased the apparent clay content of all three soils, and increased water‐dispersible clay on the LC soil. There were no significant effects of liming on soil splash, in part because of the high experimental variability of measurement. Soil erosion, measured on the field plots with a portable rainfall simulator, was in the order LC > LM > CA, a trend that corresponded to the decreasing organic‐C contents of the soils. Liming significantly decreased erosion on the LC soil, and had no effect on the other two soils. The study suggests that, while there may be some short‐term structural degradation caused by liming, the long‐term effect is to reduce water erosion.
O objetivo do presente trabalho foi verificar o desempenho de oito clones elite de batata quanto ao ciclo vegetativo, caracteres de produção e peso específico em comparação com as cultivares mais utilizadas no país. O experimento foi realizado no campo experimental da Embrapa Clima Temperado, Pelotas (RS). Foram avaliados oito clones elite desenvolvidos pelo Programa de Melhoramento Genético de Batata da Embrapa juntamente com duas cultivares comerciais, no cultivo de outono de 2011. O delineamento experimental foi em blocos casualizados com quatro repetições e parcelas compostas de uma linha com 20 plantas. Aos 95 dias após o plantio determinou-se o ciclo vegetativo dos genótipos e aos 110 dias foram realizadas a colheita e avaliações dos componentes de produção e peso específico. Após a verificação da normalidade de distribuição dos erros, os dados foram submetidos à análise de variância e de agrupamento de médias por Scott & Knott. Os clones CL02-05, CL69-05, CL27-05 e 2197-15 apresentaram maiores número de tubérculos comerciais, percentagem de tubérculos comerciais e massa média de tubérculos que as cultivares testemunhas. O clone CL02-05 revelou, além disso, o maior potencial de produção de tubérculos comerciais dentre os quatro clones. Os clones CL69-05 e 2197-15 apresentaram peso específico e ciclo vegetativo semelhantes à Asterix e também maior potencial produtivo.
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