ENERGETIC BALANCE FOR CROP-ROTATION SYSTE MS TO WHEAT UNDER NO-TILLAGE

From 1990 to 1992, at the Cooperativa Agraria Mista Entre Rios Ltda., in Guarapuava, PR, Brazil, the effect of some crop rotation systems of wheat on energetic balance was estimated. Four rotation systems for w heat were studied: 1) monoculture; 2) rotation of one winter without w heat: 3) rotation of two winters without wheat; 4) rotation of three w inters without wheat. The winter crops (oat, barley, common vetch, and wheat) and summer crops (corn and soybean) were seeded under no-tilla ge. A randomized complete block design, with four replications and plo ts with 60 m2, was used. In the 1990 growing season under monoculture wheat showed lower energetic balance than under rotation. Soybean pres ented energetic efficiency and stabilized cultural productivity of sev eral winter crop rotation systems.