Compost Production and Water Conservation
this handbook, we focus on Aerated Static Piles and worm composting (See details in chapters 4 and 5).
Managing moisture content and air flow are critical factors in a successful composting operation. When conditions are too dry, the decomposition rate will slow down and feedstocks will essentially dehydrate rather than compost. When conditions are too wet, water fills the pores needed for air flow and anaerobic conditions can result- leading to rot (and methane production!) rather than compost. Additionally, excess water can lead to run-off of nutrients that may be damaging to adjacent waterways.
While concerns of excess moisture are low in the desert, we should still consider the potential impact of run-off from the composting site in the overall design. If working on a slope, windrows should be oriented parallel to the slope, so that precipitation landing between the windrows can move freely off the composting area and are less likely to carry away partially composted feedstocks as runoff. The downslope perimeter of the composting area can also be safeguarded with a vegetative filter strip: an intentional planting of a native perennial grass or wildflower that will take up the runoff water. Piles made of compost or wood chips can also be effective at controlling runoff from sloped areas (also see image on page 45).
In the high desert, we are working with environmental factors such as high winds, low ambient humidity, intense sun/altitude, and lack of consistent precipitation. Due to these factors, we’ve selected composting techniques that reduce evaporation and moderate air flow to conserve water. In
Condensation
Precipitation Transpiration Evaporation
Compost Piles
Water Holding
‘The Water Cycle’ with compost piles incorporated for improved water holding and infiltration.
Infiltration
Pond Groundwater Flow
Graphic by Jessica Brothers
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