Two field experiments were conducted in a Mollisol of the southern region of Puerto Rico to evaluate the effect of three different tillage techniques versus no tillage on the yield of watermelon, tomato and pigeon pea. No-till (undisturbed), minimum-till (chisel plowing), conventional-till (disk plowing to 15 cm), and deep-till (disk plowing to 45 cm) were used as soil treatments (main plots). Each plot was split into 3 subplots in which watermelon, tomato and pigeon pea were planted. To measure the residual effect, we planted the-same crops in the same plots after the first harvest. Combined response of the three test crops to land preparation techniques was not significantly different, nor in general, were individual responses significantly different. Thus, watermelon, tomato and pigeon pea might be grown with minimum- or even no-tillage under the conditions prevailing at the experimental site. No significant differences among treatments were observed with regard to the analyzed plant nutrient levels, pH and soil strength. In the residual effect experiment, watermelon and tomato yields declined considerably, whereas pigeon pea yields increased.