Effectiveness of Aerated Static Pile to Windrow Composting on Small-Scale Farms

Effectiveness of Aerated Static Pile to Windrow Composting on Small-Scale Farms

Summary

Modern commercial composting facilities largely use aerated static piles (ASP) for increased efficiency, fast turnaround, odor reduction, and a superior product.  Small farmers, on the other hand, predominantly use windrows to make their compost– a cheap, labor-intensive, tried-and-true method.  We merged the technology of modern facilities with the needs of the small farm.  A small-scale ASP system is a much more efficient use of farmers’ valuable time, labor and space, and produces superior compost for their soils.

For this study, we created a small-scale, replicable ASP system to be adapted by farmers, using the expertise of technical advisor & ecological designer Adam Schwartz. We compared the capital, labor, and time spent on windrow-produced compost – the method currently used by most farmers, including myself – with our ASP model.  We predicted that the ASP model will be hugely beneficial for the small farmer,  as a labor- and space- saving method that creates a superior product.

Objectives/Performance Targets

Moon Valley Farm built a replicable ASP system, and created active compost piles in it as well as in our windrow compost system.  We carefully documented the time, labor, and efficiency of both the windrow system and the ASP system, to compare their overall quality and effectiveness for the benefit of small-farms everywhere.  We sent samples of the final products from each system to a lab for quality analysis.

We took the findings of our research to the community, through on-site workshops with area farmers & horse owners, and created a promotional video that is available online.  We are working on compiling straight-forward instructions on how to create this system for your own farm, as it is not yet widely available and will be invaluable to farmers who are looking to add an efficient composting system to their farm.

This is the link to the video we produced: http://youtu.be/eDv79H_CEMY (It was too large to upload as a separate document).

Accomplishments/Milestones

We designed and built a small-scale, replicable aerated static pile system.  We custom-built this system to fit the needs of Moon Valley Farm, and it is easily adaptable to the needs of other farms/farmers.  Additionally, we maintained the windrow pile system we had on our farm, and documented our recipe, time/labor hours, and quality for both systems.

We were able to complete and document 8 compost piles from the ASP system, and 7 windrow piles this season.  We found that the ASP system took, on average, 4 fewer labor hours to create and maintain piles compared to the windrow system.  The two systems took approximately the same amount of time to create and monitor temperature and moisture levels, but the windrow system took additional hours to turn before sifting in order to ensure that the outer layers of the pile were thoroughly composted.  

The piles were approximately the same volume, though they varied depending on the availability of materials.  The footprint of the ASP system was smaller than that of the windrow system, by 108 square feet.  However, the footprint of the windrow system was decreased this season from previous seasons, because our needs from it were decreased due to the production from the new aerated system.  

We tested finished compost samples from the two systems, and a third of an older finished heap from the previous year as a control.  We found the quality to be satisfactory in all of the results, with the pH levels being a little high (7.7) for the ASP system (compared to the 7.0 pH for the windrow, and a 6.4pH for the control).  We believe that is due to an excess of nitrogen-heavy food scraps in those piles, and that we can easily adjust the initial compost recipe to lower the food scrap inputs.  There was a learning curve for us in adjusting the compost recipe for the aerated system, because it needs to be more calculated to allow for airflow.  We used more wood chips and food scraps in the heaps than we traditionally do in the windrows to compensate, and are still adjusting the recipe to reflect what works best for the system.

Moon Valley Farm attempted to make all of our own compost for several years before this, but ended up purchasing occasionally to keep up with increased cultivation and needs for double cropping.  It is too soon to tell for certain yet, but we anticipate that the ASP system will allow us to produce all of our own compost, saving us money every year on the cost of purchased compost.

• Compost Test 2
• Compost Test 1
• Compost Test 3
• ASP System Capacity

Impacts and Contributions/Outcomes

We hosted two workshop days in late summer and fall 2014 to share our compost trials with other area farmers.  We talked with them about their own composting efforts, and many have shared that their current methods of producing compost are not successful and they purchase compost to get a reliable & fast product without the hassle.  Although we don’t know that anyone has decided to build an ASP system of their own because of our project, we do know that several area farmers are reconsidering their choice to purchase compost in light of the O2 system being a faster, cheaper, smaller-footprint and more attractive method of compost production.

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