About 8 tons of fungal vermicompost was applied to the peach trees that were planted 2 years ago near the worm compost area. The peach trees in question (about 120 trees) were smaller than other trees planted at the same time in the 6-acre block and are considered problem trees. However, as was reported in an earlier blog, these same trees received a vermicompost treatment a few weeks ago and this has produced a positive effect (growth and fruit harvest).  This is why we decided to go ahead with a second application. I want to cover the vermicompost around these trees with a layer of thermophilic compost to serve as a protective mulch and to keep the vermicompost as moist as possible. However, the workers on the farm are busy with other more important tasks and this will not be done in a timely manner.

How will the effects of vermicompost be assessed on problem trees? First and most important is the visual aspect (via photography) and the harvest yield . In addition, I am analyzing the biology (is it balanced?) before and after compost treatment. The biology will also be compared between the problem trees and the healthy trees. Finally, two types of chemical analyses will be performed. A total chemical analysis of all the nutrients present in the soil will be followed by a rhizosphere analysis (around the roots) of water extractable nutrients. These chemical analyses will be performed on healthy trees and problem trees. The goal here is not to find a silver bullet that will eliminate all problems (that is impossible). Rather the idea is to create conditions in the soil around healthy trees and problem trees that are  similar and that will result in good harvest yields. These conditions should also result in reducing water use and the application  of various nutrients.

This week I started to develop a vermicompost that will be primarily used to grow vegetables.  This compost will be made from materials that have little or no contamination with weed seeds. The major source of weed seeds is horse-bedding (and manures in general). Coffee grounds (from the Frog Hollow  Café and Blue Bottle Coffee Bar in the Ferry Building in San Francisco) will serve as a source of nitrogen in the vermicomposting process and will replace horse-bedding. I am mixing the coffee grounds (nitrogen and nutrient  source) with shredded cardboard (bulking agent and food source) and fruit residues . These materials especially the coffee grounds have to be balanced in the right proportions so that some of the coffee decompostion products do not affect worm mortality.  My past experience with coffee grounds and shredded cardboard has shown that the Eisenia fetida earthworms produce very good compost and their mortality rates are reduced with this mixture. As we ramp up this type of compost, we will discuss it in more detail. By the way, 29 September is celebrated as National Coffee Day in North America.

Author: Christophe Kreis MLF Soil Consulting PhD, Molecular Biology/Developmental Biology, University of British Columbia, Canada. Christophe is co-founder of MLF Soil Consulting with his wife Monique. He started his career in basic medical research and after various positions in academia and industry Christophe slowly returned to his first passion Soil Ecology and Microbiology. It is his belief that human health is tied intimately to soil health through the production of healthy food. For this reason MLF Soil Consulting is committed to help farmers improve the management of their soil through composting, vermicomposting and biological analysis of microbial soil life.