Sonoma Mountain Institute

After 5 weeks there has been no significant difference between the control and the one time treatments in both the oak leaf litter and the harding grass thatch bins. Here is a picture taken at 5 weeks…page down and compare to the initial photo…

The next phase will begin with a once a week treatment following the initial amounts of compost, compost tea and water. (see 1-3 listed below). I will continue this until total decomposition.

1.    Control Bin – this bin will receive 4 cups of water with each treatment session (to establish the same amount of added moisture as the Tea Bin)
2.    Tea Bin – this bin will receive 1 cup of compost tea mixed with three cups of water evenly distributed over the top layer of thatch and leaf litter.
3.    Compost Bin – this bin will receive 2 cups of compost and 4 cups of water with each treatment session (the 4 cups of water is to establish the same amount of added moisture as the Tea Bin)

Our perennial dry grassland community is dominated by Phalaris aquatica (harding grass). Phalaris aquatica has a large biomass creating a thatch layer that can be over six inches deep. The thatch build up inhibits the potential of other species to germinate and become established, leading to a monoculture of grass opposed to a variety of plant species found in a healthy native community.

Dr. Ingham’s hypothesis is thatch buildup in the grasslands is due to low fungal activity.  She believes we can achieve significant to total litter decomposition within a month’s timeframe.

In previous experiments, the biological treatments used had no appreciable effect on either thatch buildup or fungal activity biomass [see grassland experiment, Biology Analysis].  Possible explanations include, 1) fungal foods inadequate, and/or 2) the correct species composition is absent and/or the number of decomposition fungi is not adequate in our previous compost/compost tea.

In this small-scale trail, we will be looking at the effect of compost and compost tea as the biological amendments as treatments for breaking down the thatch layer of Phalaris aquatica and the leaf litter of Coast Live Oak.

Set Up

Phalaris aquatica thatch
Fill 3 bins (24-gallon totes) with 2 inches of grassland soil from the perennial dry community and cover the soil with 4 inches of Phalaris aquatica thatch. The thatch collected was ½ laying on the ground and ½ cut from standing dead plant material

Oak Leaf Litter
Fill 3 bins (24-gallon totes) with 2 inches of soil from the oak woodland and cover the soil with 2 inches of leaf litter.

Treatments
The initial phase of this trail will be a one-time treatment. The final thatch/leaf litter remaining will dictate our next step.
1.    Control Bin – this bin will receive 4 cups of water  (to establish the same amount of added moisture as the Tea Bin)
2.    Tea Bin – this bin will receive 1 cup of compost tea mixed with three cups of water to evenly distribute the tea over the top layer of thatch and leaf litter.
3.    Compost Bin – this bin will receive 2 cups of compost and 4 cups of water (the 4 cups of water is to establish the same amount of added moisture as the Tea Bin)

Testing:
Direct observation of soil (inches of soil, inches of litter)
Compost Test & Compost Tea Test

Week One: 3/17/08
Phalaris aquatica – All Bins
no change – 2 inches of soil and 4 inches of thatch
Oak Leaf Litter – All Bins
no change – 2 inches of soil and 2 inches of leaf litter

Week Two: 3/23/08
Phalaris aquatica – All Bins
no change – 2 inches of soil and 4 inches of thatch
Oak Leaf Litter – All Bins
no change – 2 inches of soil and 2 inches of leaf litter

Week Three: 4/1/08
Phalaris aquatica – All Bins
2 inches of soil and 3.5-4 inches of thatch (it appears that the thatch has settled more. Possibly  due to rains last week. No change in soil depth)
Oak Leaf Litter – All Bins
no change – 2 inches of soil and 2 inches of leaf litter

Week Four: 4/9/08

The grow-box trial started on 10.17.07, to evaluate the effect of compost tea applications on native grass seed and native wildflower germination and growth in a “grow-box”, has come to a close leaving me with more questions.

To see full write up: Grow Box Project Write Up PDF

To see a spreadsheet of the foodweb data: Grow Box Spreadsheet PDF

In short, because this was not a replicated study and the initial soil biology numbers may have been slightly different than the compost test results from October 1, 2007, it is difficult to make a conclusive statement of the effects of the compost tea on the final soil biology values. What is interesting, is that there was an observable visual difference in the germination rate and first 8 weeks of growth between the compost tea treated grow boxes and the non-treated grow-boxes and not a clear distinction in the soil biology results. It is worth noting, at the end of January, both sets of grow-boxes respectively, appeared at similar growth height and density. Is it possible that there would have been a noticeable trend in the soil biology in the initial 8-weeks of this project to correspond with the visual observations? Or is it possible that the compost tea affected the soil chemistry and stimulted the growth of the compost tea treated grow-boxes? This project has stimulated several ideas for other projects, particularly, to conduct a similar observational study evaluating the effect of compost tea applications on the germination of native grasses with a sterile soil medium and/or a soil medium collected from our grasslands. Considerations would be to add replication, initial soil biology and soil chemistry tests and repeat the tests at the five to six week mark of the project. Perhaps adding the variable of compost in comparison to compost tea on germination and continued growth on native grasses.

In the below photos the compost tea treated grow-boxes are in the front (from left to right):

1) 10.26.7 2) 11.02.07 3) 11.11.07- Grass CT Treated on the Rt 4) 01.29.07