PROPERTIES OF STRAWS

 

Straw is an agricultural by product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as wheat, rice, barley, oat and rye. It has many uses, including fuel, livestock bedding and fodder, thatching and paper-making. It is usually gathered and stored in a straw bale, which is a bundle of tightly bound with twine or wire. Bales may be square, rectangular, or round, depending on the type of balers used.

bale of straw     loose straw     cut straw

 

Chemical Composition of Wheat Straw and Softwood/Hardwood


Cell wall Composition (% of dry weight) Wheat Straw Softwood Hardwood
Stalk Node Leaf
Cellulose (%) 40.0 40.0 35.0 42.0 42.0
Hemicellulose (%) 45.0 40.0 55.0 28.0 35.0
 Lignin (%) 15.0 20.0 10.0 30.0 23.0

Cell Wall, Silica and Extractive Content of Wheat Straw and Softwood/Hardwood


Plant Composition (% of dry weight) Wheat Straw Softwood Hardwood
Stalk Node Leaf
Cell Wall 90.0 79.0 76.0 95.0 93.0
Silica 3.0 8.0 11.0 <0.5 <0.5
Extractives 7.0 13.0 13.0 4.5 6.5

Cell Characteristics of Wheat Straw and Softwood/Hardwood


Cell Characteristics Wheat Straw Softwood Hardwood
Stalk Node Leaf
Length (mm) 1.3 0.5 1.5 2.0 93.0
Diameter (mm) 0.015 0.015 0.015 0.030 0.020
Lumen % 75 50 80 65 55
Tissue Density (g/cc) 0.34 0.68 0.27 0.49 0.63
Fiber Length and Diameters of various Straws
Straw & Stalk Fibers Length (mm) Diameter (micron)
Cereal Straw 1.5 23
Wheat Straw 1.0-1.5 13
Corn Straw 1.0-1.5 18
Rye Straw 1.5 13
Oat Straw 1.5 13
Barley Straw 1.5 13
Rice Straw 0.5-1.4 8-10
Canola Straw 0.8-1.8 24-38
Corn Stalk 1.0-1.5 16-20
Sorgum Stalk 1.0-1.7 20-47
Cotton Stalk 0.6-0.9 20-30
 

The Chemical Composition  of various Straws

Straw & Stalk Fibers Alpha Cellulose Lignin Holo-Cellulose Pentosans Ash
Canola Straw 48.5 20.0 77.5 17 6.6
Corn Straw 33.6 17.5 64.8 - 9.5
Wheat Straw 38.2 15.3 74.5 - 7.8
Rice Straw 48.2 17.3 70.9 24.5 3.5
Bongkot 42.7 17.2 70.0 27.2 0.9
Sunflower 37.5 182 74.9 - 7.0

More Info

  1. Sugarcane Bagasse Paper versus Wheat Straw Paper by Omar Omari, Marcus Cheung, Robert Chen, Hugo Chen
  2. Wheat Straw as a Paper Fiber Source Prepared by Recycling Technology Assistance Partnership. Prepared for The Clean Washington Center



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