EFFECTS OF WINTER CROPS AND ROTATION SYST EMS ON SOME AGRONOMIC CHARACTERISTICS OF SOYBEAN

The effects of winter crops and rotation systems on some agronomic cha racteristics of soybean were assessed at the Cooperativa Agraria Mista Entre Rios Ltda., in Guarapuava, State of Parana, Brazil. Four croppi ng systems to soybean were tested: I) monoculture soybean/barley; II) rotation soybean/corn in sucession of barley/commom vetch, from 1984 t o 1989, and rotation soybean in sucession of barley/white oats, from 1 990 to 1993; III) rotation soybean/soybean/corn in sucession of barley /flax/commom vetch, from 1984 to 1989, and rotation soybean/corn/soybe an in sucession of barley/commom vetch/white oats, from 1990 to 1993; and IV) rotation soybean/soybean/corn/soybean in sucession of barley/f lax/commom vetch/white oats. Both winter and summer were grown under n o-tillage, except in 1989 when limestone was applied before planting w inter crops. A completly randomized block design with four replication s and plots with 60 m(2) was used. Soybean crop can be cultivated afte r white oats and barley, with no restriction. Differences in the mean agronomic characteristics evaluated were observed on rotation systems studied.