Corn stubble height and residue placement in the northern US Corn Belt II. Spring microclimate and wheat development

Crop residue management systems are yet needed in the northern Corn Belt of the USA that hasten sowing and early establishment of crops in the spring. This study was conducted to investigate the effect of corn stubble height and residue placement on the soil microclimate and associated development of wheat in early spring. Treatments were established after corn harvest in the autumn of 1993–1995 and included 60 cm stubble, 30 cm stubble, 30 cm stubble with adjacent interrows devoid of and covered with prostrate residue (30 cm stubble with banded residue), 0 cm stubble, and 0 cm stubble without prostrate residue. Five rows of wheat were sown by hand into one corn interrow on 12 April 1994, 3 April 1995, and 24 April 1996. Leaf development on the main stem was assessed twice weekly until late May. Net and reflected global radiation, soil temperature, and soil water content were measured in each treatment throughout the spring. Vegetative development of wheat was hastened in soils with little residue cover (0 cm stubble without residue treatment and the bare interrow of the 30 cm with banded residue treatment). Averaged across years, the phyllochron ranged from 75 °C day per leaf for treatments with little residue cover to 92 °C day per leaf for the residue interrow of the 30 cm stubble with banded residue treatment. Vegetative development in treatments with little residue cover was hastened by soil temperatures that were at least 1 °C higher throughout spring than those of the residue interrow of the 30 cm stubble with banded residue treatment. The 0 cm stubble without residue treatment was warmer because of a smaller albedo (at least 0.03) and greater net radiation (at least 0.5 MJ m⁻² per day) compared with all other treatments. Little difference in soil water content was found among treatments, although treatments with little residue cover were wetter in two of the three springs. Based on the results of this study, one can conclude that soils with little residue cover or that have taller stubble on the surface will absorb more radiation and thereby enhance soil warming and early development of plants in the northern Corn Belt of the USA.