BROAD CREEK WINDROW TEMPERATURE OBSERVATIONS Bud Malone University of Delaware

General Comments: Temperature probes were placed in duplicate at one foot depth at one location for each of the 12 treatments. Previous data suggest this is the hotter portions of windrows and that windrows typically heat from the outside inward. The core of the piles are cooler and take longer to get the target temperatures needed. The windrows were turned at 4.5 days and spread at 6.5 days. Pathogen inactivation data is not available to date. As will be discussed, differences in litter moisture and method of pile construction limit any direct comparison of one house to another. The data can only be discussed in the context of time to reach and maintain peak temperatures. Temperature Data for All Houses: As shown in the graph below the temperatures reached 130F by the end of the first day and peaked at 147F before starting to decline. The implications of turning will be discussed later. LITTER MOISTURE Litter moisture differences between and within houses limits comparisons of many treatments. It should be noted moisture appears to have a major influence on windrow temperatures. The following are the initial and final litter moistures taken at the one foot depth next to the temperature probes: House Initial Moisture Final Moisture Comment 1 24% 19% 5% loss 2 26% 22% 4% loss 4 29% 28% 1% loss Moisture losses were greatest with the Brown Bear houses (1 and 2) compared to the skid-steer house (4) which also had larger piles. After the piles had equalized in moisture content over time, there appeared to be strong correlation (r=0.75) between final litter moisture and windrow temperatures during the last 2 days of monitoring (see graph below). Initial moistures were somewhat variable and may reflect difficulty in getting representative samples.     Brown Bear vs. Skid Steer All three houses reached 130Fin similar amount of time (2.0 to 2.3 days). However, peak temperatures in the Brown Bear houses (H# 1was 140F at 3.0 days, H#2 was 152Fat 2.8 days) were achieved about one day less than the skid steer house (H#4 was 151Fat 3.7 days). Other benefits observed with the Brown Bear would be no cake removal. The amount of time required to form 2 rows/house (using proper equipment and trained operator) would be about equal to the time for 2 skid-steer loaders to do the same size house. The Brown Bear houses might have less moisture (ammonia yet to be determined) but would have some uncomposted litter along the sides and corners.     COMPOST ADDITIVES Since the windrows were constructed differently in H#4, the only true comparison of additive vs. no additive is in H# 1 and 2. Both the CF4 and LDM treated litter appeared to reach the target temperature of 130Fabout 4 hours quicker than the control. However, the CF4 had 6F higher temperature than the control (131 vs 125) during the first 3.5 days. Although LDM temperatures were only 3F higher than control during the first 3.5 days, during the first 1.5 days they were 9F higher (130 vs 121). It is uncertain if the CF4 organisms can sustain the higher compost temperatures while the LDM is more effective in getting higher early temperatures but start to die at 150F???           Turning Windrows: When the windrows were turned, temperatures dropped 9F compared to unturned piles the first day but increased an average of 5F higher than unturned the second day. Turning would have the benefit of mixing the cooler pile core temperatures for secondary heating but uncertain if this is practical or justified (need pathogen data to support the benefit of turning).   Day Post Turn There was no difference between the time to achieve peak temperatures in H#l with 2 windrows vs. H#2 with 1windrow (3.0 vs. 2.8 days). Both houses appeared to sustain peak temperatures for -24 hours. House 4 with the skid-steer had half the house with one long continuous pile and the other half with 3 larger piles. Both achieved peak temperatures in 3.7 days but the long piles sustained these temperatures for 1.2 days while the larger piles sustained peak temperatures for 2.8 days. Although the larger piles maintained temperatures for a longer period of time, the core temperatures might be less.     SUMMARY Based on these limited observations, the results might suggest (until more supporting data available): 1 Brown Bear might achieve peak temperatures quicker, helps dry out and recondition litter. 2 Forming 2 rows per house with the Brown Bear is probably the most efficient with no difference in temperatures from larger windrow, large piles with skid-steer are slower to reach peak temperatures. 3 Data suggest compost additives might help achieve higher initial temperatures 4 Until pathogen data is available, uncertain if turning is justified (this study did not evaluate pathogens in the core of the windrow, only at 1 foot depth). 5 Litter moisture is critical in achieving desired temperatures. For more information, please look at the following pages Brown Bear Poultry Litter Report Litter Reconditioning Strategy In House Composting of Litter (Timely Topics 2007) Greg Newhart Farm (Brown Bear Windrow composting trial) East Coast Integrator Broad Creek Windrow Observations

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