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Agronomy Journal Abstract -

Distribution of Small Grain Residue Produced by Combines1


This article in AJ

  1. Vol. 77 No. 5, p. 730-734
    Received: Oct 30, 1984

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  1. R. R. Allmaras,
  2. C. L. Douglas Jr.,
  3. P. E. Rasmussen and
  4. L. L. Baarstad2



A uniform distribution of small grain residues is needed in conservation tillage systems, but measurements are needed to describe the degree of uniformity or nonuniformity actually produced by combines. A combination of hand-cut bundles of wheat (Triticum rrestivum L.) plus straw before a combine pass; straw plus chaff deposit on a canvas apron and hand-cut bundles of the uncut stubble were used to measure the distribution of small grain residue produced by 12 test combines. Header width varied from 5.5 to 7.3 m, grain production from 4.8 to 7.1 Mg/ha, and straw (plus chaff) production from 9.0 to 11.4 Mg/ha. From 52 to 64% of the straw plus chaff was threshed. An uneven residue distribution ratio (URDR) of maximum total to minimum total residue varied from 1.4 to 5.1 depending on combine and residue distribution system. A dispersion index (DI), which ranges from 0 for an even distribution to approximately 0.5 for a severely uneven distribution, varied from 0.09 to 0.42. All test combines with a standard flail spreader gave DI > 0.23. Dispersion indexes ≤ 0.14 were produced by a retrofit chaff spreader on a cylinder-type combine, a farm-shop modified flail spreader system on a rotary-type combine, and an experimental straw chopper on a rotary combine. Agronomic and machinery operation problems associated with chaff rows suggest an URDR < 1.5 is needed to successfully manage no-till after small grain harvest. A DI < 0.l can be attained without excessive costs to improve spreading devices.

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