Tree Experiment Final Analysis

Tree Experiment Background:
In June of 2006, Sonoma Mountain Institute (SMI) began a replicated study on the effects of five different biological treatments for improving the health of diseased oak woodlands.

Tree Experiment Data Sheet

The experiment treatments (outlined below) were applied to three separate blocks of six plots each on the SMI property, and replicated in another block of six plots at the Occidental Arts and Ecology Center (OAEC).
The treatment applications were:
• White Plot: Control / Water
• Red Plot: Water plus 1 unit of fungal food
• Green Plot: ACT (Aerated Compost Tea)
• Blue Plot: ACT plus 1 unit fungal foods (turf pro/fish hydrolysate)
• Yellow Plot: ACT plus 5 units fungal foods
• Pink Plot: ACT plus a thin layer of compost

Data Analysis:
In November of 2007, SMI employees prepared all of their collected data from throughout the course of this trial for a statistical analysis done in collaboration with Dr. Elaine Ingham of Soil FoodWeb.

During our initial setup of these trials, our goals were non-specific. We simply wanted to try these applications and observe any affects that may come as a result. Our data from these trials consists of 4 sets of soil biology tests, 2 sets of soil chemistry tests, 4 sets of soil compaction readings, and simple field observations done by SMI staff.

Based on analysis of soil biology, soil chemistry and field observations, our first general observation was that none of our treatments had a dramatic affect in any of the plots. While this broad conclusion has support, we also realized that without an annual record to use as a baseline, we needed to consider seasonal variance when looking at any datasets.

We were able to draw the following conclusions from our data:

I. Active fungi and active bacteria numbers are lower in the drier times of year, when plant activity and soil moisture are reduced, and more active in wetter times of the year when plant roots are releasing more exudates, which reflects an expected seasonal trend in soil biology.

II. The Oak woodland ecosystems are overall slightly fungally dominant. Dr. Ingham observed that the fungal to bacterial ratios in our plots are not at the level they should be for a healthy oak forest. Her research has shown that a much more fungally dominant condition is necessary for proper nutrient cycling, disease suppression and plant productivity. Therefore, any future work should focus on increasing the total and active fungal biomass in this system.

III. There was no significant change in soil biology in any of our treatment plots as compared to the control plots.

IV. Dr. Ingham made several comments on the soil chemistry data in these plots, noting some data that seemed significant, but acknowledged that more data was needed, especially reliable seasonal trends before we could draw any absolute conclusions. Some observations from these data:
• The buffering capacity of all plots samples way much higher than expected, indicating a compacted condition.
• The soil organic matter in all plots was lower than expected, which suggests that proper decomposition and nutrient cycling is not happening. Dr. Ingham believes that the lack of total ands active fungi in our woodlands is contributing to this condition.

All involved parties agree that these experiments are valuable and provide needed data. However, there is also general agreement that the initial design and implementation of these trials and treatments was not done properly. Early observations indicated that the compost and compost tea being used in these experiments was simply not good enough, biologically speaking, to be used in a field trial. Later applications were done using somewhat better compost and compost tea, though still not up to the Soil Foodweb standard that is used to measure the biological component of these treatments. Likewise, the overall design of these trials lacked the background research and tools for evaluation that should be a part of any experiment at this scale. While the number data itself is useful, the observations made of the process of setting up and running the trials may be the more important component of our data from which we learn.

The final element to carry from these trials is that we were unable to significantly shift the soil biology and soil chemistry in this oak woodland ecosystem using the treatment materials we had available at that time. These trials are finished, but should be repeated at some point in the future, perhaps on a much smaller scale, using compost and compost tea that meets the Soil Foodweb inc. standards to truly document any effects positive or negative that they might have in this system.

Leave a Comment