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

CURRENT RESEARCH PROJECTS

CSU Autumn, 2005, Vol. 13, No. 4, p. 232-233
CROP RESPONSE

Effects Of Composted Hazelnut Husk On Growth Of Tomato Plants
Investigator: Damla Bender Ozenc, Department of Soil Science, Karadeniz Technical University, Ordu, Turkey
Objectives: To observe the effect of composted hazelnut husk on growth of tomato plants, and to determine suitable mixture ratios with soil under greenhouse conditions to increase horticultural use. Turkey is first with respect to hazelnut production in the world, and it is basic income for people in the

Black Sea region. Hazelnut is cultivated on approximately 600,000 hectares in Turkey, yielding a harvest of 550,000 to 600,000 tons. After harvest, the dry husk represents about one-fifth of the residue which becomes a problem for the producer and region every year.

ENVIRONMENTAL IMPACT
Reliability Of Bioassay Tests For Herbicide Residues In Compost Of Varying Salinity And Herbicide Levels
Investigators: W. F. Brinton, E. Evans and T.C. Blewett; Woods End Research Laboratory and Dow AgroSciences
Objectives: To evaluate the reliability of detecting plant damage from herbicide residues with and without adjusting for background electrical conductivity, using composts of varying clopyralid content. The study compares two bioassay protocols and employs a range of green waste composts, which varied regarding salinity and clopyralid content. Results demonstrated that high levels of conductivity, frequently encountered in composts, lead to interfering effects that comprise assessment of herbicide damage.

MATERIALS AND METHODS
Stability Of Mixed Food Residuals Composted With Low-Technology Methods
Investigators: Teresa L. Matteson and Dan M. Sullivan, Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon
Objectives: To evaluate the efficacy of low technology, outdoor composting methods to produce a compost with a low, stable decomposition rate; and to determine reliability of simple, rapid compost stability evaluation methods. This study - initiated by the Oregon Dept. Of Environmental Quality (DEQ) - involved regulators, composters, consultants and academia. The DEQ study evaluated outdoor composting of mixed food waste using two low technology processing treatments, limited turn windrow and passive aerated windrow under western Oregon climatic conditions.

Comparing Biological Quality Of Potting Media Based On Different MSW Composts
Investigators: A. Moldes, Y. Cendon, E. Lopes and M.T. Barral; University of Santiago, Spain; University of Vigo, Spain; Escuela Politechnica Superior, Lugo, Spain
Objectives: To evaluate MSW compost as an alternative to peat in preparation of growing media. MSW composts were obtained from conventional aerobic composting and anaerobic digestion followed by aerobic curing. Composted pine bark was also evaluated as well as mixed with MSW compost. Germination and above-ground growth were recorded and calculated to propose best combinations of substrate components.

Effects Of Hydrated Lime On Transition From Mesophilic To Thermophilic Composting Conditions
Investigators: A. Boen, 0. Bergersen, R. Aasen and R. Sorheim; Jordforsk - Norwegian Center for Soil and Environmental Research, As, Norway
Objectives: To document in laboratory-scale 1) effect of lime addition on pH and microbial activity; and 2) response of different doses of lime on the initial composting phase of source separated organic household waste. Effects of hydrated lime (Ca(OH)2) addition on early stages of composting of source separated organic household waste (SSW) were studied in lab-scale composting reactors. Temperature development was monitored and oxygen concentrations in the composting material measured regularly the first 100 hours. The SSW was acidic and inhibition of microbial activity was observed at temperatures higher than 45-50°C. By addition of adjusted doses of lime, it was possible to achieve a faster establishment of high-rate respiration under thermophilic condition. “Addition of lime can be an interesting alternative for fast establishment of high-rate composting of acidic SSW in large-scale composting,” observe the researchers.

MICROBIAL ECOLOGY
Phytotoxicity Of Biosolids Compost Of Different Maturity Degrees Compared With Biosolids And Animal Manures
Investigators: M.S. Zubillaga and R.S. Lavado, Agronomy Faculty, University of Buenos Aires, Argentina
Objectives: To determine the phytotoxicity of biosolids compost at different times of the composting process as well as its causes, while comparing other organic amendments. As part of the germination bioassay, root growth percentage was calculated along with electrical conductivity, pH, phenol content and volatile organic acids. Potentially toxic elements, volatile organic acids, phenolic compounds and ammonia were not related to the germination test. The researchers did not exclude occurrences of unknown phytotoxic substances, which degrade as composting proceeds.