Wood ash from a wood-fired, electrical generating plant was examined as a potential amendment in municipal biosolids and yard waste com posting applications. The rate of composting and the final compost quality (chemical, physical, and plant growth characteristics) were examined. Yard waste (leaves, grass, and wood chips) and a municipal biosolids-chip mixture w ere either not amended or amended with wood ash at eight percent or five percent by weight, respectively, and then com posted outdoors in insulated, 1700L, aerated reactors. Yard waste piles heated rapidly to 60°C within six to seven days, whereas biosolid piles heated more slowly to a maximum of 52 to 57°C within nine to 11 days. Ash had little, if any, effect on the time-temperature response. In general, ash-amended compost had higher pH, plant nutrient, and salt contents. Tomato plants (Lycopersicum esculentum) produced 100 percent more shoot biomass in biosolids than in yard waste compost media. Poor plant growth in the yard waste compost was likely due to the high initial pH and salt content of the growth medium. In yard waste media, tomato plants germinated and produced more shoot biomass in the control compost than in the ash-amended compost.A pH neutralization study indicated that wood fly ash could be used as an economical substitute for lime which is commonly used to stabilize municipal biosolids prior to land filling or land application. Wood fly ash (pH= 13.2-13.4), when added to biosolids at a 2 to 1 ratio by weight, raised the pH of the mixture to 12.0.

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Log yard residues (LYR) a bark and soil waste material produced during log handling, could find use as a growth medium for plants. In this study, log yard fines (LYF), a screened fraction of the LYR (<1.3 cm), were either not amended or amended with a N-S fertilizer mixture (LYF + F) or with cow manure (LYF + M) and then composted outdoors in insulated, aerated tanks for 18-22 weeks. The resulting substrates were then evaluated as growth media for 'Chief crimson clover (Trifolium incarnatum L.) and 'Streaker' red top (Agrostis alba L.). Plants were fertilized (0 or 78 kg N/ha) and grown in a growth chamber.Temperatures in the LYF and LYF + F piles were similar to ambient conditions over the 5-6 month treatment period, whereas the manure-amended pile reached a maximum of 34°C after two weeks and then cooled to ambient after two additional weeks. The final C/N ratio of the nonamended LYF was 85 as compared to 36 for LYF + M and 44 for LYF + F. Clover and red top grew best (height and biomass) in LYF + F and poorest in LYF + M, regardless of fertilization regime. Red top grew poorly in the nonamended, unfertilized LYF presumably due to the high C/N ratio of this medium. In summary, this study suggested that LYF could be either amended with fertilizer and aged in piles or directly land applied with supplemental fertilization to support plant growth.

The following is an edited version of a discussion held by the Middle East Policy Council on September 23, 1994, at the U.S. Senate Hart Building in Washington, D.C. The Council's president, former Senator George McGovern, was the moderator.

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