Compost Science Complete scientific data on compost process control and end product quality

PERSPECTIVE

Compost Science & Utilization, (2007), Vol. 15, No. 4, 219

A Complete Range Of Studies
REFLECTING on the topics that are so inherent in the nature of composting, this issue once again assembles the critical qualities that affect both the science and utilization of the end products. In their opening paper on estimating dry matter mass balance, Larney and Buckley observe that the most

accurate approach was using carbon concentration to calculate organic matter and treatment effects. “Accurate estimates greatly improve nutrient mass balance calculations to gauge success of manure handling practices,” they conclude.
For Griffin and Hutchinson with the USDA and University of Maine laboratories, the challenge is understanding relationships between compost maturity and nitrogen availability. Their observation: Methods of characterizing compost maturity and stability that more realistically reflect the composting process are better predictors of N release and potential plant inhibition after incorporation into soil.
Based on their study of properties of 12 composts sourced from United Kingdom composting plants, the goal of Dimambro, Lillywhite and Rahn was to determine whether the products could be used as growing media or for application to farmland. The composts contained 100 percent source segregated BMW - or mixtures of mixed MSW. In this study, source segregated composts could be considered for use in agriculture or as growing media in the horticultural industry, but the mixed MSW contained high levels of glass and plastic, in addition to high concentrations of the PTEs. “Until a greater proportion can be removed, contaminants and PTEs will limit use of these types of compost in agriculture,” they concluded.
In their analysis of open-air windrows for winter disposal of frozen cattle mortalities, Stanford and colleagues at Canada's Agricultural Centre demonstrated that freezing temperatures “provided no barrier.” Stacking up to 3 layers of full-sized cattle mortalities in a windrow did not affect temperature profiles, residual flesh or bone, or analyses of finished compost.
Roberts, Edwards-Jones and David Jones at the University of Wales point out in their paper, that compared to traditional windrow composting, in-vessel techniques often represent more effective options due to reduced production of bioaerosols and leachate, and the potential for better process control. After the active compost phase was over, and the compost removed from the vessel and matured outside, they demonstrated that covering the compost was essential to preserve compost quality. Their study “clearly showed that cocomposting of waste feedstocks can be used to successfully manipulate the chemistry of the final compost - making it suitable for multiple end uses.” In addition, their work demonstrated that careful management of the compost maturing phase is also required to maximize quality and minimize pollution.
In the concluding paper in this issue, Mugnai and colleagues discuss the effects on growth and plant water relations in their evaluation of composted green waste (CGW). They added CGW to peat-based media in increasing amounts and observed that a higher CGW content (75 or 100 percent) increased plant susceptibility to water shortage; and peat-based media partially amended with CGW may have positive agronomic and economic consequences for commercial ornamental nursery production.
As we approach a new year, the research published in this issue of Compost Science & Utilization continues to advance the use of compost as well as the efficiency of composting operations, globally.

Jerome Goldstein