EARLY CHANGES IN THE TRANSITION FROM CONVENTIONAL TO NO-TILLAGE IN A VOLCANIC SOIL CULTIVATED WITH BEANS (Phaseolus vulgaris L.)

Conventional tillage (CT) is a soil management system commonly used by small farmers in the Ecuadorian highlands; they remove the soil during seedbed preparation to eliminate weeds, improve soil aeration, avoid compaction, and develop adequate rooting space. CT causes changes in physical, chemical, and biological soil properties but, in the long run, have negative effects on crop performance. Most of these effects can be avoided by using no-tillage (NT). The objective of this study was to determine the initial effects of NT, different fertilization rates and depth levels of sampling on yield and soil chemical and physical properties after the first crop cycle (prior to crop rotation scheme). A long-term field experiment was established to study the soil changes derived from the transition from CT to NT systems in a volcanic soil of the Ecuadorian highlands cultivated with the following crop rotation schemes: beans (Phaseolus vulgaris L.)-corn (Zea mays L.)-beans and beans-amaranth (Amaranthus caudatus L.)-beans. The results for the first crop cycle show that bean yield was 42% higher under NT compared to CT, indicating that the soil improvements promoted by NT had effects on crop yield; however, only the changes in pH and water storage capacity presented significant differences, levels of soil organic matter, total N, available P, and bulk density showed a trend towards improvements under NT. This suggests that NT allows for increased crop yield and improved crop rotation performance in the medium and long term