Soil Organic Matter Mineralization after Compost Amendment
1996
Sikora, L. J. | Yakovchenko, V.
The addition of composts and manures to soils has often resulted in increased plant yields that are not obviously related to the nutrients in the added organic material. A study was conducted to determine if compost additions to soil resulted in increased mineralization of soil organic matter (SOM). The organic matter of a Sassafras sandy loam soil (fine-loamy, siliceous, mesic Typic Hapludult) was labeled with ¹⁴C by incubating uniformly labeled wheat (Triticum aestivum L.) straw with the soil through a minimum of 60 wetting-drying cycles during 2 yr. A municipal solid waste-biosolids compost (MSWC) or a biosolids compost (BC) was added to the labeled soil or to acid-washed sand and incubated for 1440 h. Decomposition of MSWC was low with 95% of the compost-C remaining in sand or soil after 1440 h. Ninety-two percent of BC-C remained in sand and 86% remained in soil after 1440 h. Total and ¹⁴CO₂ data indicated that neither compost stimulated SOM decomposition. Municipal solid waste-biosolids compost reduced slightly SOM decomposition at 545 and 715 h. The soil, however, stimulated BC decomposition. Nitrogen mineralization of the BC + soil mixture was greater than soil alone, and the N apparently came from the compost. The benefits from addition of BC to Sassafras soil was not attributed to increased mineralization of SOM.
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