ABSTRACT A widespread assumption among researchers and technicians is that stony soils are more susceptible to degradation. However, the role of rock fragments in the hydrology of stony soils, especially in regard to infiltration, is still a research gap. The aim of this study was to test the hypothesis that an increase in rock fragments in the soil profile increases the water infiltration rate. Infiltration tests using a double-ring infiltrometer were conducted on February 11, 2021, and December 11, 2022, at three sites of Entisols with different fractions of rock fragments. The results supported the hypothesis of this study. The infiltration rate was up to sixteen times greater in profiles whose horizons had at least 60 % rock fragments in relation to profiles with a lower fraction of rock fragments. These findings provide evidence that some stony soils may not be as susceptible to degradation by water erosion as it was suposed.

RESUMO Em experimento conduzido no campo quantificou-se o período de viabilidade de escleródios de Sclerotinia sclerotiorum. Escleródios naturalmente produzidos em plantas de soja numa lavoura comercial foram coletados numa máquina de pré-limpeza. Utilizou-se no trabalho os escleródios produzidos na medula das plantas e com tamanho de aproximadamente oito mm de comprimento e 1,9 mm de diâmetro. Cinquenta escleródios foram acondicionados num recipiente feito com tela de nylon branca (25 x 25 cm) com malha de 0,25 mm. Oitenta recipientes foram posicionados na superfície do solo simulando o plantio direto. Mensalmente foram removidos quatro recipientes. O solo aderido às embalagens foi removido com jato d´água de torneira, os escleródios lavados, submetidos à assepsia com hipoclorito de sódio e postos a germinar em areia de rio esterilizada, em câmara de crescimento a 15oC e fotoperíodo de 12h. Os escleródios, mantidos na superfície do solo, perderam a viabilidade em 12 meses. Conclui-se que o banco de escleródio no solo, sob plantio direto, pode ser reduzido pela rotação de culturas com espécies vegetais não suscetíveis.

ABSTRACT The longevity of Sclerotinia sclerotiorum sclerotia was quantified in an experiment carried out in the field. Sclerotia naturally formed in soybean plants in an infested commercial field were collected in a grain-cleaning machine and those present in the stem pith, with c.a. 8 mm in length and 1.9 mm in diameter were selected. Fifty sclerotia were kept inside a white nylon mesh (0.25mm) screen bag (25 x 25cm). Eighty bags were laid on the soil surface-simulating no till farming. At monthly intervals, four bags were taken and brought to the laboratory. Sclerotia were washed with tap water and surface desinfested with sodium hypochlorite and exposed to germinate on sterilized moist river sand in a growth chamber at 15oC and 12h photoperiod. After 12 months, sclerotia kept on the soil surface, lost their viability. It may be concluded that under no till, crop rotation with nonsusceptible crops, can reduce the sclerotia bank in the soil.