00575naa a2200205 a 450000100080000000500110000800800410001910000200006024500760008026000090015665000120016565000180017765000120019565000150020765300170022265300150023970000250025470000170027977300730029618032142017-04-18       1990    bl ---       0--  u    #d1 aLANGDALE, G. W.  aCropping frequencies to sustain long-term conservation tillage systems.  c1990  atillage  aConservação  aLavoura  aProdução  aConservation  aProduction1 aWILSON JUNIOR, R. L.1 aBRUCE, R. R.  tSoil Science Society of America Journalgv.54, n.1, p.193-198, 1990.