Susceptibility of row-planted soybean (Glycine max) to the rotary hoe

A three-year study was conducted to determine soybean susceptibility to phy sical damage from cultivations done with the rotary hoe in a weed-free situ ation. Plot size was large enough to enable the rotary hoe to be used at a speed of 15 km h(-1). The soybeans were systematically cultivated at eight growth stages, from pre-emergence to fourth trifoliate leaf. Two, three and four cultivations were done on a combination of growth stages. Soybean pop ulation decreased with the number of cultivations but yields were either no t affected or significantly increased compared with the uncultivated contro l. Cultivations with the rotary hoe could be done up to the 4th trifoliate leaf growth stage without risk of decreasing yield.