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Spatial Variation of Crop Residue Incorporated by Tillage
Author(s) -
Staricka J. A.,
Allmaras R. R.,
Nelson W. W.
Publication year - 1991
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1991.03615995005500060028x
Subject(s) - tillage , plough , residue (chemistry) , crop residue , agronomy , chisel , soil science , environmental science , chemistry , materials science , biology , ecology , biochemistry , metallurgy , agriculture
Spatial distribution of crop residues incorporated by tillage is generally unknown even though the soil environment for roots, soil microbes, and water flux may be greatly affected. Variations in depth and concentration of oat ( Avena sativa L.) residue and tracers (ceramic spheres and polyethylene chips) were measured after incorporation by disk, chisel, or moldboard plow as a primary tillage. Depth distribution of root tissue in an untilled area was also measured. In 1987 and 1988, 60 to 120 soil cores (1.8‐cm diam.) per treatment were taken to a 30‐cm depth immediately after tillage and sectioned into 2‐cm increments (a 5‐cm 3 volume). Residue amount, tracer presence, and soil bulk density were measured in each 5‐cm 3 sample. Moldboard‐plowing treatments incorporated crop residue to a depth of 28 cm; chiseling and disking incorporated residue to 10 cm. Despite differences in depth of incorporation between tillage treatments, residue and tracers were generally in a 10‐cm band of each 30‐cm‐deep core from all tillage systems. Frequency distributions of residue concentration in individual 5‐cm 3 samples were not normal (Gaussian); rather, they were monotonic and positively skewed. Maximum concentrations of crop residue in a 5‐cm 3 sample (135.0 mg cm −3 in 1987 and 48.1 mg cm −3 in 1988) were similar among tillage treatments and were greater than the average concentration by a factor of 10 for disk and chisel and 30 for moldboard plow. Samples containing incorporated residue had a distinctly higher soil porosity than samples in general. Primary tillage buries crop residue without effectively dispersing in a microscopic scale throughout the tilled zone. Ceramic spheres and polyethylene chips worked equally well as tracers for incorporated residue.