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