CULTURAL PRODUCTIVITY OF CROP-ROTATION SY STEMS FOR BARLEY, UNDER NO-TILLAGE

Over a ten-year period (1984 to 1993), in Guarapuava, Parana Brazil, t he effect of crop rotation systems on barley was assessed. Four rotati on systems for barley were studied: system I (barley/ soybean); system II (barley/soybean and common vetch/corn, from 1984 to 1989, and barl ey/soybean and white oats/soybean, from 1990 to 1993); system III(barl ey/soybean, flax/soybean, and common vetch/ corn, from 1984 to 1989; c ommon vetch/corn was replaced by white oats/soybean, from 1990 to 1993 ); and system IV (barley/soybean, flax/soybean, common vetch/com, and white oats/soybean). The objective of this work was to evaluate the cu ltural productivity of these four rotation systems under no-tillage. F rom 1984 to 1989, the systems II (2.19 kg/Mcal) and III (1.89 kg/Mcal) showed a higher energy conversion rate, as compared to system I (1.54 kg/Mcal). No difference was found between systems IV (1.81 kg/Mcal) a nd I. From 1990 to 1993 the systems II, III and IV, whose average cult ural productivity indexes were 1.89 kg/Mcal, 2.02 kg/Mcal, and 1.88 kg /Mcal, respectively, did not differ from system I (1.68 kg/Mcal); howe ver, the annual cultural productivity indexes of systems III and II we re either higher than or did not differ from system I.