Composting of organic wastes to use as soil amendments or in potting substrates offers great potential for diversion of these wastes from landfills. The chemical and physical characteristics of 12 composts containing (by volume) spent mushroom substrate (50%), waste waxed corrugated cardboard (WCC, 0%, 25% or 50%), and/or pulverized wood wastes (PWW, 50%, 25%, or 0%) were measured during two separate windrow composting periods (14 to 18 weeks). Supplemental N was added to some of the composts in the form of poultry manure and/or soybean processing wastes. During the first 8 to 10 weeks, composts containing 50% WCC tended to reach and maintain higher temperatures, but subsequently cooled more rapidly. Microbial activity (CO2 evolution) also was initially higher in these composts but fell by week 12 to levels, comparable to composts containing 50% PWW. The paraffin wax in WCC-containing composts was degraded almost completely (>95%). Total N (1.2% to 1.6% DW), P (0.30% to 0.55%), and K (0.9% to 1.2%) concentrations were within, typical ranges but highest in composts containing 50% WCC. KCI-extractable NH4-N (494 mg N/kg) and NO3 + NO2-N (281 mg N/kg) were highest and lowest, respectively, in composts containing 50% WCC. Electrical conductivity (4.5 to 8.5 mS·cm–1) and pH (7.5 to 8.5) were high in all composts and highest in composts with 50% WCC. Concentrations of phenolic compounds were highest in composts containing 50% WCC, manure, and soybean wastes. C:N ratios of all composts were within an acceptable range (18 to 23.1).
Effects of Poultry Manure and Spent Mushroom Substrate on Soil, Weed and Maize Performance in an Ultisol
