One of the greatest soil amendments is homemade compost. The benefits of adding recently decomposed organic matter to garden soil are improved soil tilth (structure), water holding capacity, microbial activity and it supplies macro and micronutrients to your garden plants. My home compost pile began with primarily 60% carbon (straw, stalks and dry leaves) mixed in with 40% nitrogen (grass clippings, food scraps and fresh plant material from the garden). I selected this system since a temperature of 140 F is quickly attained. During the season, I attempt to maintain the aforementioned ratio of plant materials while also adding food scraps to the mix. The food scraps decompose promptly and are consumed by earthworms in a matter of 1 to 2 weeks. I will occasionally add a small amount of nitrogen fertilizer to stimulate microbial activity. Last, I monitor the moisture of the compost pile to ensure that microbes remain healthy and active.
Now that I am a Garden Leader at St. Joseph Street Community Garden (Columbia, MO) my vegetable gardening and composting efforts are done there. Due to the size of the garden and number of gardeners involved, we’ve established a 4-bin compost system to allow for a higher volume of material to go through the decomposition process. The size of each compost bin is 3.0 ft tall and 4 ft. long and wide. I no longer have access to fresh cut grass, so I use fresh plant material from the garden and surrounding area. I continue to use dry leaves and straw for a carbon source. The sides of the bins are welded wire to ensure that the piles have sufficient aeration, and we typically turn the piles 2 to 3 times per season.
Manure in the Mix
We are presently looking into securing animal waste to add into our compost system. In our area it is possible to secure horse manure, for free, if one is fortunate enough to have a truck. The cause for such high interest in utilizing farm animal* waste is due to the high content of nitrogen, phosphorous and potassium (N, P and K) in their excrement. Data from the University of Massachusetts, Amherst, Extension, indicates that animals excrete approximately 70 – 80% of the N, 60 – 85% of the P and 80 – 90% of the K found in their feed. Of course, the type feed and animal will have a bearing on the levels just mentioned.
At our community garden, we plan to stockpile a small quantity of horse manure near to our 4-bin system. This will allow us to add a few shovelfuls of manure to complement our original mix of materials, as needed. The addition of composted manure to the garden plot contributes to the soil’s nutrient supply and will improve soil structure. However, I don’t rely on the manure’s content of N, P and K to satisfy the total nutrient demand by my crops. This is especially true for eggplant, sweet corn, beans and tomatoes.
*Caution – there is a claim that warns against using pig manure. Apparently, certain pathogens and parasites are not destroyed during the composting process.