The influence of different tillage methods on seedling emergence, emergence force and yield of soybean (Glycine Maximum (L) Merrill) were investigated in a two-year experiment for a sandy loam soil at florin, Nigeria. Four tillage methods, no till (NT), chisel ploughing (CP), rotavation (RT) and conventional tillage (CT) were compared during the cause of the experiment. Seedling emergence force was obtained by assuming that the weight of soil heaved by seedlings upon emergence is proportional to the force causing emergence. The percentage emergence for the two years on the average were higher for the no-till and chisel tillage systems than in other treatments. No significant differences in seedling emergence force (SEF) was observed among the tillage treatments. The no-till treatment exhibited higher seedling emergence force in relation to the other tillage treatments. The lowest SEF value of 0.96N was associated with the highest yields of 1.26 and 1.27 t/ha for both CP and CT, respectively, during the 1990 growing season. A similar trend was observed in 1991. Soybean yield generally decreased with time irrespective of the tillage treatment. Grain yields were similar and lowest for NT and RT. The Chisel tillage method was found to give the highest seedling emergence and yield, comparing all tillage methods used in this experiment. Results from the studies on the mechanics of seedling emergence yielded a simple but functional empirical relationship that could be used for computing seedling emergence force.
