Ecosystem Engineers

A citation from a recent review article entitled “Vermiculture technology: reviving the dreams of Sir Charles Darwin”: compared to human beings, earthworms have over 600 million years of experience as “ecosytem engineers” (Rajiv K. Sinha)

• In a blog at the beginning of October, we described how a large number of trees (about 1000) have been uprooted at Frog Hollow and will be replaced with new trees next spring. The holes in which new trees will be planted were filled with a mixture of thermophilic compost and vermicompost. One of the important components of composts is humus. Humus is part of the non-living, non-tissue component of soil organic matter (SOM). Humus is the hard to digest plant materials that remain in organic matter after the easily digested portions have been consumed at least once by the various decomposers (bacteria, fungi and other creatures). Humus is made up of persistent organic molecules from plant cells such as oils, resins, lignins, and waxes that resist further decay by the various decomposers. Humus particles are negatively charged and act as magnets for any positively charged particles that pass their way. Thus, humus binds many particles that are essential for plant growth and microbial growth in the soil: examples are calcium, potassium and plant hormones (plant substances that regulate growth) which, when bound to humus, are not leached out of soil. Finally, humus is derived from organic matter and eventually, but only after many years, it returns to being carbon dioxide, water and minerals. The term humus is synonymous to the terms found in commercial literature: humic acids and humic substances. Several peer reviewed studies have shown that vermicomposts produce enough humus to have a positive effect on plant growth. Plants treated with humic acids extracted from vermicomposts produce significantly more fruits and flowers than those treated with commercially produced humic acids. Commercially produced humic acids have different origins (mining, peat bogs, wetlands, good and bad compost) and their use remains controversial because of their heterogeneity. At Frog Hollow, we hope to replace all commercial humic substances with well managed and well characterized vermicomposts and thermophilic composts. Typically, vermicomposts produce humus/humic acids in a shorter time period than thermophilic composts. Also, using on-site produced composts as a source of humus/humic like substances is less expensive and ecologically more responsible than reliance on commercial sources.

• This week, about 77 tons of compost from a thermophilic windrow was applied in the orchard. The average temperature of this windrow dropped to 100 F last week-end and the compost was analyzed for the biology (fungal dominance) in time to beat the rain that came down today (Friday). Hopefully, if enough rain comes down today, we can turn the new windrows (that have been constructed in the last two weeks) on Monday without having to water them (rain or no rain, we still have to worry about the drought).

• A new vermicompost pile will be available for spreading sometime in the next two weeks. Worms were removed by trommelization from a worm bed that looked ready (by visual criteria) for spreading. This vermicompost is being presently being analyzed for the biology and for stability/maturity.
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