like the other guys said, lot of variables. what are the other farmers doing in your area? if you have a lot of wind and water erosion, i wouldnt moldboard. i do corn and soybeans conventional tillage, disk chisel in the fall and hit it with the field cultivator in the spring. how deep you plow/chisel also, watch your field tile depth. lot of iowa guys run subsoilers with moleballs. my neighbor pretty much no -tills, but after8 years or so, the ground got pretty compacted. (combines and grain carts helped to pack it good) 2 years ago i helped him v-rip in the fall(he ran the stalk chopper, i followed pulling the v-ripper.) really helped a lot. ran the ripper about 15 inches with the winged points. it loosens the soil in the fall to get water down deep but leaves a lot of trash on the surface to slow erosion. heres a couple pics of the ripper in corn. 5 shank dmi on a 7060 allis. really made her snort in some spots!!
the allis is about 160 hp.