Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 7, 2000
Publication Date: April 1, 2001
Interpretive Summary: Waste paper accounts for a large part of the materials usually disposed of in landfills, but some landfills no longer accept waste paper. As a result, other means for disposing of waste paper are needed. One means would be to apply the paper to cropland as a mulch, provided the paper did not cause the land to appear trashy. This could be done by applying paper pellets to the land. This experiment was conducted to study the effect of a paper pellet mulch on soil water storage and grain sorghum yield. Mulch rates were 0 (check), 5, 10, and 15 Mg/ha. Treatments involving wheat residues being retained on or removed from the plots and sweep tillage or no-tillage were included. Applying the pellet did not result in greater soil water storage or sorghum yields. This was because the pellets absorbed water from rain or snow. As a result, water evaporation was about the same from bare and mulched soils. Residue and tillage treatments had little effect on water storage and sorghum yield. Soil carbon contents were greater where pellets were applied than in bare soil in one case, but some pellet material was still on the soil surface. With more time for decomposition, soil carbon contents could increase. Applying the pellets also improved soil aggregation. These improved soil conditions (more carbon and better aggregation) could improve crop production. Crop production was not harmed by applying the paper pellets. As a result, waste paper in a suitable form (for example, pellets) can be disposed of on cropland. Mixing the paper with soil to increase the decomposition rate would be a better practice than applying the paper to the soil surface, as was done in this study.
Technical Abstract: Some landfills no longer accept waste paper for disposal; thus alternative disposal means are needed. One means would be to apply pelleted paper to cropland as a mulch. This study was conducted to determine effects of a paper pellet mulch on soil water storage and grain sorghum [Sorghum bicolor (L.) Moench] yield. Mulch rates were 0 (check), 5, 10, and 15 Mg ha**-1. Wheat (Triticum aestivum L.) residue condition (retained or removed) and tillage (sweep or no-tillage) treatments were included. Pellet applications did not result in increased water storage or sorghum yields, apparently because pellets absorbed precipitation, which resulted in similar evaporation from bare and mulched soils. Residue and tillage treatments had little effect on water storage and sorghum yield. Soil C concentrations were greater in mulched than bare soil in one case, but some pellet material remained, suggesting further decomposition could increase soil C concentrations. Pellet applications resulted in greater aggregate mean weight diameters and lower percentages of small aggregates. These improved soil conditions could improve the soil's long-term productivity. Because crop productivity was not harmed, waste paper in a suitable form (e.g., pellets) can be disposed of on cropland. However, shallow incorporation to hasten its decomposition would be a better practice than surface applications, as used in this study.