Fort Collins, CO | rmiller@colostate.edu

Dr. Miller is an affiliate professor in the soil and Crops Science Department at Colorado State University. He received his BS and MS degrees from the University of Nebraska, and his Ph.D. degrees at Montana State University. He served as the Director of the University of California Davis Diagnostic Laboratory and Extension Soil Specialist from 1988 to 1997. Since 1997 he is the coordinator of three lab proficiency testing programs.

For the past 22 years he has coordinated the STA Compost-Certified Laboratory aka Compost Analysis Proficiency (CAP) Program, which assess methods and laboratories based on the US Compost Council method manual- the Test Methods for the Examination of Compost (TMECC). The program provides three compost materials tri-annually to eighteen laboratories in North America, and is required for STA Certified Compost participants testing their products. Since 1997 the STA Compost-Certified Laboratory program has evaluated 189 compost materials collected across the US and Canada.

Session Code: 6D

Track: STA

Session Name: STA Program Updates & Benefits

Session Time: Thursday, February 8, 2:00 – 3:30 PM

Presentation Title: Assessment of Transport Coolers for Shipping Compost for Laboratory Analysis

Presentation Description: USCC protocols for laboratory analysis of compost requires one-day shipping to the testing laboratory. Due to increased shipping costs, a study was initiated in January 2023 to assess the temperature stability of compost based on two day shipping. The study assessed: (1) two types of transport coolers; (2) three different quantities of Ice brix; and (3) two different external temperature regimes 24 and 22 C. Six Onset data loggers were placed in multiple positions within shipping coolers and data collected in 2 minute intervals for 50 hrs. In all studies 10 lbs of moist compost was used. Results show the optimum ratio of Ice Brix to compost is 1:1 with 40% of the total ice brix mass placed on the bottom of the cooler and 60% on the top of compost samples. Transport cooler with 2” side walls were superior to 1.2” side walls and maintained compost sample intern at temperature below 7 C for across all temperature regimes. These results clearly demonstrate that transport coolers with 2” walls and sufficient Ice brix mass can maintain compost shipping temperatures below 7C for periods up to 50 hrs, and thereby reduce shipping cost.

The Compost Analysis Proficiency Program (CAPP) is part of the Seal of Testing Assurance Program operated by the US Composting Council. Blind Compost Samples are sent to the participating laboratories in the program, analyzed and the data is statistically studied by Dr. Robert Miller, the Program Director. Reports are generated with details of these results and this presentation will provide an updated on CAP and those reports.