Hp. Dossantos et Em. Reis, CROP-ROTATION IN GUARAPUAVA .17. ENERGETI C EFFICIENCY OF ROTATION SYSTEMS FOR BARLEY CROP, UNDER NO-TILLAGE, Pesquisa agropecuaria brasileira, 29(7), 1994, pp. 1075-1081
In the period from 1984 to 1989, at the Cooperative Agraria Mista Entr
e Rios Ltda., in Guarapuava, PR, Brazil, the effects of rotation syste
ms for barley on energetic efficiency were assessed. Four rotation sys
tems for barley were studied: 1) monoculture; 2) one winter without ba
rley; 3) two winters without barley; 4) three winters without barley.
Both winter (white oat, barley, common vetch, and flax) and summer (co
rn and soybean) crops were seeded under no--tillage. The energetic eff
iciency is the ratio of grain yield of each crop by the cropping energ
y, represented by the commodities and labor executed in the cropping s
ystems. Energetic efficiency of crops studied was influenced by the cr
opping period. White oat and barley crops showed higher energetic effi
ciency than the other winters crops. The best energetic efficiency was
obtained for corn.