“…The effects of these different tillage practices on yield have been evaluated in different regions of the U.S. (Bordovsky et al, 1998;Mullins et al, 1998;Wesley et al, 1988) and throughout the world (Fischer et al, 2002;Ghuman and Sur, 2001;Grant and Lafond, 1994;Iqbal et al, 2005;Lal, 1976), for different soil types and for different crops (Tsuji et al, 2006) and rotations (Dick and Van Doren, 1985;Wilhelm and Wortmann, 2004). The general development in most of these systems has been an increase in positive impact or decrease in the negative impact of no tillage on grain yield (Cahoon et al, 1999;Dick et al, 1991;Edwards et al, 1988) and accumulation of soil organic matter in the soil surface (Grant and Lafon, 1994;Dick, 1983;Hussain et al, 1999;Karlen et al, 1989;Rhoton et al, 1993). Eight years of no-till on a Grenada silt loam soil for different crops was evaluated to determine the time factor required to improve soil properties under no-till and this was determined to be four years (Rhoton, 2000).…”