Ohio State University Fact Sheet

Community Development

700 Ackerman Road, Columbus, OH 43202-1578

Comparative Decomposition Rates for Shredded Newsprint, Straw, and Sawdust

CDFS-124-98

John D. Rohrer, Ph.D.
Assistant Director, OSU Extension Community Development

Joe E. Heimlich, Ph.D.
Leader Environmental Sciences, OSU Extension

In bedding trials, it has been observed that newsprint has less wet strength than straw. In fact, in liquid manure systems, newsprint tends to break apart into very small pieces during handling/pumping operations. Depending on the handling systems of manure, long fibers in straw may or may not be desired. The trend during the last ten to fifteen years has been toward more liquid systems, particularly for hog, beef, or dairy, and some poultry operations. In liquid systems, fine particles such as sawdust and shavings must be used for bedding or materials such as newsprint that will break up very readily.

Newsprint tends to "decompose" or, at least, the fibers break apart quite rapidly when saturated with livestock manure and applied to the farmland at normal rates. Bedding materials, when used in commonly accepted bedding practices, result in a wide variation of moisture saturation depending on animal species and management practices. This research was conducted to determine comparative decomposition rates for different types of bedding materials that were incorporated into the soil in an outside natural environment.

Studies were conducted during the summer of 1989 to observe the decomposition of shredded newsprint, straw, and sawdust without manipulation.

Methodology

A plot was prepared to incorporate bedding material in soil test bed 2 feet wide and 9 feet long for each of the three bedding materials. The 9-foot long strips were subdivided into three 3-foot long segments and labeled A, B, and C. In the Section A of each strip, 1 to 2 inches of the bedding material was incorporated into the soil by spading and working the soil to a depth of approximately 6 inches. This resulted in approximately a one third mixture of the bedding material in each of the "A" sections of straw, sawdust, or newsprint. In the Section B of each strip, the amount of bedding material was doubled and incorporated 6 inches deep resulting in approximately one half mixture of soil and bedding material. In Section C of each strip, approximately 6 inches of soil was removed and an even layer of bedding material 3 inches deep was deposited. The 6 inched of soil was then replaced on top of the bedding materials. After the plots were established, no additional moisture was added, but during observations, natural rainfall kept the soil and bedding materials moist, but not saturated. As the soil test beds were established, photographs were taken to identify each of the three test beds and the three treatments for each bedding material.

Selected Observations

Observation 1

After 11 days, the bedding materials were damp, but no decomposition was noticed in any of the test beds. The newsprint did tear somewhat more easily than normal because of the damp condition, while the straw, also damp, required nearly the same force to tear or shred as dry straw.

Observation 2

After five weeks, the soil conditions were dry on the surface but moist at least an inch below the surface.

Sawdust and shavings - Sections A and B. The sawdust and shavings bedding material tended to blend with the dry surface of the soil. Sawdust that was in a moist condition under the surface of the soil crumbled readily and nearly disintegrated when rubbed between the thumb and forefinger.

Sawdust and shavings - Section C. Sawdust layered 6 inches below the surface was nearly black in color and crumbled when rubbed.

Newsprint - Sections A and B. Where single sheets were in contact with moist soil, the print was still readable and tended to disintegrate with a firm touch. When rubbed firmly against the soil, it completely disappeared. Where paper wads of six or eight sheet strips, 1 inch wide, were buried together, the print was still readable, and when rubbed together, the material developed the consistency of a well-worked piece of warm putty. Dry paper near the surface barely changed in appearance, but tore easily.

Newsprint - Section C. The thick layer of newsprint was very readable without much color change. It was very moist and tore easily.

Straw - Sections A and B. The dry straw on top or in the top inch of soil did not change much in color and strength. When pulled, it separated with a snapping sound. The buried straw pulled apart with less effort and without a snap. With considerable rubbing between the thumb ad forefinger, it disintegrated into long fibers and with persistent rubbing it became a damp was of fibers.

Straw - Section C. The plug of straw was damp and quite tough with a golden color. The straw snapped when pulled with sufficient tension.

Observation 3

Observations and photographs were taken approximately six weeks after soil application. The buried sawdust still had a leathery texture. The layer of sawdust in Section C changed in color, but was not decomposed.

The newsprint was moist, still readable and not decomposed.

The straw was still very pliable and yellowish in color. In Section C the straw slice was more moist and tended to be matted together.

Observation 4

Approximately six weeks into the study, the sawdust was barely distinguishable on the surface. Upon digging in Section A much of the sawdust seemed to have simply disappeared or decomposed into the texture of the soil. In Sections A and B, the sawdust layer buried 6 inches deeps was black in color and individual particles were indistinguishable. It was difficult to identify the original material by looking at the decomposed layer. The newsprint in test beds A and B were found to be still readable particularly when several layers were stuck together. Single layers tended to be crumbled and were less readable. The newsprint crumbled or wadded very easily when touched or rubbed. The layer of newsprint buried in Section C was damp and cream colored. Twenty pages together were easily torn but were still readable. When rubbed together the newsprint broke apart easily between the thumb and forefinger.

The straw in Sections A, B and C was still intact, but broke longitudinally because of strong fibers in the straw. The straw had a leathery texture when pulled or worked.

Observation 5

In observations 16 weeks after initiation of the test, the sawdust was black and very crumbly. The newsprint was readable when found in layers of many pages, however, single pages disintegrated unless found in the upper, drier portions of the soil. The straw buried even at the lower depths was still yellowish in color but tore easily.

Conclusions/Implications

1. Of the three bedding materials tested, the fine shavings and sawdust material decomposed most readily. These materials, if kept moist, were completely decomposed at the end of the 16-week test period. The newsprint and straw were more closely paired in decomposition rates. The newsprint did decompose or at least disintegrate more quickly than did straw when kept in similar moist conditions on the soil. The straw was most persistent in retaining its color and strength because of the long fibers. At the end of the 16-week study period, the straw was still yellowish in color and tore very easily. Most of the newsprint and straw were not decomposed.

2. Barn management practice will determine, to a great extent, the amount of exposure of bedding materials to animal manure. This exposure, observed in field trials greatly alters the rate of decomposition of bedding materials. In lagoon systems, paper bedding has been observed to break apart within six hours, in pack barns, paper bedding is virtually indistinguishable before removal.

3. Straw has become an expected visual component of barns and fields. Paper, in the same use and amount is often viewed as litter. Management practices for utilization of newspaper for animal bedding must incorporate efforts to control excess paper and paper trails. Allowing paper bedding to be further incorporated into manure may prevent problems when land applied.

Brief

This fact sheet, one in a series reports data from that examined newsprint as an alternative bedding material for farm animals. The study was funded in part by the Ohio Department of Natural Resources, Division of Litter Prevention and Recycling. The study addressed newsprint with black ink and examined the supply of newsprint in Ohio, effects of the paper bedding, as well as the absorption and decomposition. The bedding was evaluated on management and disposal, animal behavior, and aesthetics. The newsprint bedding was shredded into small bales. Evaluators commented on the ease of use, stall maintenance, storage and disposal of the newsprint. They also observed animal behavior such as grazing on the newsprint, grooming of the animals and insulation qualities. The general appearance of barns and fields were qualitatively assessed as to dust levels and stall and barn appearance.