ANALYSIS OF THE CULTURAL PRODUCTIVITY OF CROP-ROTATION SYSTEMS FOR WHEAT, UNDER NO-TILLAGE

From 1984 to 1993, in Guarapuava, PR, Brazil, the effect of systems of crop rotation on wheat was assessed. Four rotation systems for wheat were studied: system I (wheat/soybean); system II (wheat/soybean, comm on vetch/corn, from 1984 to 1989, and wheat/soybean, white oats/soybea n, from 1990 to 1993); system III(wheat/soybean, flax/soybean, and com mon vetch/corn, from 1984 to 1989, and wheat/soybean, common vetch/cor n, and white oats/soybean, from 1990 to 1993); and system IV (wheat/so ybean, legume/corn, barley/soybean, and white oats/soybean). Cultural productivity (kg of commodity/Mcal consumed) during that period is pre sentend in this paper. From 1984 to 1989, systems II (2.20 kg/Mcal), I II (1.91 kg/Mcal), and IV (1.83 kg/Mcal) showed a higher conversion ra te, as compared to system I (1.52 kg/Mcal); system II was the best opt ion. From 1990 to 1993 systems II, III, and IV, whose average cultural productivity indexes were 1.93 kg/Mcal, 1.96 kg/Mcal, and 1.91 kg/Mca l, respectively, did not differ from system I (1.78 kg/Mcal); however, the annual cultural productivity indexes of system II showed no diffe rence from system II or exceeded it, becoming, therefore, a good alter native to replace wheat/soybean monoculture.