Tillage Residual Effects On A Crop Rotation Of Taro, Cabbage And Eggplant In Oxisol, Ultisol And Vertisol Soils In Puerto Rico

An experiment was established to evaluate several tillage treatments and their residual effect on a crop rotation that included taro, cabbage and eggplant. The experiment was established at three ecologically different locations with three different soil series and orders. At two locations (Ultisol and Vertisol soils), the treatments were conventional tillage; conventional tillage - no beds; deep till + conventional tillage; and deep till. At the third location (Oxisol soil) the treatments were no-till; conventional tillage; deep till + conventional tillage; and deep till. Taro was planted after soil preparation according to the treatments. The crops that followed in the rotation were planted no-till in the same plots. A fifth treatment, in which all crops in the rotation were planted under conventional tillage, was used as a check. In the Oxisol soil, taro yields in the no-till plots were significantly lower than yields in any of the other treatments. There were no yield differences among the other treatments. In the Ultisol soil, the higher taro yields were obtained in plots where no beds were raised (deep till and conventional - no beds); whereas in the Vertisol soil the lowest yields were obtained in the deep tilled plots. Yields of cabbage and eggplant were not significantly different among treatments in the Oxisol and Ultisol soils. In the Vertisol soil, cabbage yields were significantly higher in plots with the continuous conventional tillage. The results suggest a positive residual effect from the tillage operations performed prior to planting the taro crop in the Ultisol. The good physical properties of the Oxisol soil probably contributed to the lack of differences in cabbage and eggplant yields.