Hp. Dossantos et al., CULTURAL PRODUCTIVITY OF CROP-ROTATION SY STEMS FOR BARLEY, UNDER NO-TILLAGE, Pesquisa agropecuaria brasileira, 31(10), 1996, pp. 721-727
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.