The most important and perhaps difficult operation to accomplish under such a system is a good seeding. A heavy seeder is required with strong coulters that can cut through the mulch. This would result in poor germination rate. A trash whipper may be used in order to clear the seeding row from residue. A major drawback of conservation tillage is the increased consumption of pesticide and nitrogen.
Weed control is more difficult because of the lack of mechanical weeding.
Colder and wetter soils result in slower nitrification as well as increased denitrification. It is necessary to find ways of achieving soil conservation while reducing energy consumption. Poor yields were usually obtained with ZO because of inadequate placement of the seed and loss of nitrogen as the manure was left on the surface. In 1989, in the same experiment under the direction of Dr. O'Halloran, solid dairy manure was replaced by liquid manure. In all the tillage treatments, the corn which received manure was taller and greener than the corn which received inorganic fertilizers.