Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering


The continuing trend towards no-till crop production places considerable emphasis on the planter to create a suitable environment for plant growth;The effects of plant residue cover and soil physical conditions associated with conservation tillage systems, were assessed in relation to emergence and early growth of corn (Zea mays L.) and winter wheat (Triticum aestivum);Increasing the residue-free area above the seed from 0 to 16 cm resulted in higher soil temperatures and improved early growth of corn at normal planting depths. Shallower planting helped offset the depressive effects of complete residue cover;Two types of grain drills were considered to be less effective than a unit planter with respect to seed placement and resulting soil conditions after planting, but because of good soil moisture conditions, emergence and early growth of winter wheat was similar for all planting methods;Increasing the vertical load on two styles of press-wheels from 215 to 645 N often increased the soil bulk density in the seed zone, but with adequate soil moisture, this had little effect on plant growth. Planter press-wheels may have a greater effect on early plant growth under drier conditions or on less well structured soils;A study conducted in the growth chamber demonstrated that residue cover can improve emergence, early growth, and water use efficiency of corn when soil moisture is limiting. Bulk densities exceeding 1.25 Mg/m('3) had the greatest effect on increasing soil moisture loss through evaporation and on reducing plant growth when soil moisture contents approached 'field capacity'.



Digital Repository @ Iowa State University,

Copyright Owner

Calvin Wayne Lindwall



Proquest ID


File Format


File Size

141 pages