Decomposition in the Field of Buried and Surface‐Applied Cornstalk Residue

Abstract

AbstractThe decomposition of cornstalk residue placed on the surface of soil or buried in soil in the field was followed during a corn crop‐growing season by removing from the soil at various times subsamples of decomposing residue contained in glass‐cloth bags. Decomposition during the season (20 weeks) amounted to 50% of the surface residue and 65% of the buried residue. Half of this decomposition occurred in 8 weeks and in 5 weeks for surface and for buried residue, respectively.There was little change in the total N content of surface residue throughout the season. Nitrogen was not immobilized. However, the C/N ratio declined from 57 to approximately 30.A maximum of 12 pounds of N per 3 tons of residue per acre was immobilized by buried residue. This occurred after 3 weeks incubation. Thereafter, total N content of the residue declined. A net loss of N occurred after 5 weeks with no N fertilization and after 15 weeks' with N fertilization. The C/N ratio declined from 57 to 22. The decline in C/N ratio, both with surface and with buried residue, was caused by loss of carbon from the residue rather than an increase in total N.Early season growth of corn plants was retarded by surface residue, but the retardation was not a consequence of N immobilization. A slight retardation of growth with buried residue might, in part, have been caused by immobilization of N.