A Long-Term Rotational and Manurial Trial in Uganda

Abstract

Mean yields and average trends with time are given for cotton, finger millet and groundnuts grown in a rotational experiment during the period 1936–64. The experiment, which ran for five cycles, involved a five-year rotation with three different resting periods, five types of resting cover, and farmyard manure at three levels. Yield trends differed from crop to crop, and a critical level of total soil nitrogen is suggested in partial explanation. Responses to farmyard manure in most crops increased over die years, with increasingly marked negative curvature in a pattern that showed most strongly in cotton crops immediately following the application of manure.