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

Abstract

The 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.

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

“…Slopes were compared among treatments at P<0.05 P>/−t/ is the probability of a greater absolute value of the slope (/t/) 1997). Although crop residues are often on the soil surface, there is a greater chance of partial incorporation and decomposition as the season progresses (Parker 1962). The wide C/N ratio and the relatively large amounts of readily decomposable carbon compounds leads to prolonged nitrogen immobilisation by micro-organisms, rendering the nitrogen unavailable for crop growth in the short term ) thus high nitrogen inputs are required when poor quality crop residues are used as mulch.…”

Ammonia volatilization and soil nitrogen dynamics following fall application of pig slurry on canola crop residues

“…However, the amount of N 2 O + N 2 produced by denitrification is usually much smaller than the NH 3 losses (Dendooven et al 1998b) and other mechanisms have likely been involved to explain this apparent loss of mineral N in the INCORP plots. An increase in nitrogen immobilization in the first days following incorporation of crop residues (Parker 1962) may also have partly counteracted the greater NH 3 volatilization in SURF than in INCORP plots.…”

Decomposition of grain-corn residues (Zea mays L.): A litterbag study under three tillage systems

“…Generally, residues left on the soil surface, as in no-till and reduced tillage systems, decompose more slowly than buried residues (Parker 1962;Ghidey and Alberts 1993;Schomberg et al 1994). Surface-placed residues have reduced residue-to-soil contact and greater fluctuations in temperature and moisture content, limiting the amount of time during which conditions are favourable to the decomposers (Summerell and Burgess 1989).…”

“…Other approaches include direct sampling of unenclosed residues (Alberts and Shrader 1980), and CO 2 monitoring and/or 14 C or 13 C measurements (Azam et al 1985;Balesdent and Balabane 1996;Rochette et al 1999), in field or laboratory conditions. Past litterbag studies of corn residue decomposition in the field have used mixes of different plant parts (Parker 1962;Ghidey and Alberts 1993;Gregorich and Ellert 1994;Zaborsky 1995). Most appear to have included only stems and leaves in their mixtures; some have also included husks (Havis and Alberts 1993;Gregorich and Ellert 1994).…”