Tag Archives: compost

Pathogen-Reducing Compost

January 14, 2020
© 2020

Benefits of compost are widely known: 1) enhances water holding capacity, soil structure, organic matter, drainage, and nutrient holding capacity of soil, 2) provides a source of beneficial microbes, 3) decreases both inputs (to your garden) and outputs (from your garden), a plus for sustainability, and, 4) reduces fertilizer and pesticide use.

However, did you know that well-made compost has the ability to reduce pathogens and enhance plant growth?

An extensive research study of 120 bioassays, involving 18 composts and seven pathogens, found positive disease suppression in 54 percent of the treatment combinations, a disease stimulating effect only rarely (3%), and no effect in 43 percent of the treatment combinations (Termorshuizen et al., 2006).

Other studies have shown that “backyard” compost is superior to the commercial product, possibly due largely to richer and varied starting materials, plus a more relaxed thermophillic phase (wherein temperatures are sanitizing but lower than those recorded in commercial composts). Backyard composting presented higher counts of bacteria, actinomycetes, and fungi. It also shows higher percentages of isolates producing extracellular enzymes which allow the breakdown of tough substrates, including polyethylene!

Although the studies show the efficacy of compost, no one has come up with the perfect recipe or management strategy to combat a particular soil pathogen. This is because the soil microbial community is so dynamic and complex. Quality control tools are also lacking.

Still, we know from research that microbial organisms in compost are able to reduce pathogens my means of: direct antagonism (antibiotic production and direct parasitism), predation, competition for resources, enzyme production, and, induced resistance in plants – through signaling networks and hormones.

Sun, Jan 19, 2-4. work party
Sat, Feb 1, 10-12, Work Party
Sat, Feb 1, 1-3, PRUNING CLASS
Sun, Feb 16, 2-4, Work Party
Sat, Mar 7, 10-12, work party

Note, compost is more effective as a pathogen prevention method than when used as a management strategy for some existing soil or plant pathogen. Elaine Ingham, veteran soil scientist, points out that compost and soil should be colonized with a sizeable and diverse body of microbes. “There are only so many seats at the table. If the good guys are already there, the bad guys are turned away.”

Image Credit: Zosia Rostomian & Jill Banfield, Creative Services, Berkeley Lab

Who are these microbial actors who play such a beneficial role in a garden? It’s bacteria, fungi, protozoa, and nematodes, none of which can be seen with the naked eye. There are millions of microbes in a gram of compost and hundreds of thousands different species. In fact, it’s the diversity of players that makes good compost a pathogen suppressor.

Commercial composts can differ widely in their suppressive effects and can vary as to which pathogens are diminished. However, commercial composts can meet the objective of adding organic matter to the soil. In contrast, the special compost that you can produce with backyard composting, using correct temperature, moisture, aeration and curing processes, will yield a compost that you can use sparingly as an inoculum throughout your garden. It will jump-start good soil biology and maintain nutrient cycling, creating an environment fostering pathogen-suppressive soil.

Next up – A template on making a thermal compost.
Also, watch the FreewayEstates.org calendar for a hands-on thermal composting class, coming in early May, 2020

Ruth

References:

Hadar & Papadopoulou, 2012 – Suppressive Composts: Microbial Ecology Links Between Abiotic Environments and Healthy Plants DOI: 10.1146/annurev-phyto-081211-172914

Vaz Moreira et al., 2008 – Diversity of Bacterial Isolates from Commercial and Homemade Composts. DOI: 10.1007/s00248-007-9314-2

Welgarz et al., 2018 – Microbial diversity and nitrogen-metabolizing gene abundance in backyard food waste composting systems DOI: 10.1111/jam.13945

Fayolle , L., 2006 –  Eradication of Plasmodiophora brassicae during composting of wastes
https://bsppjournals.onlinelibrary.wiley.com/doi/full/10.1111/

Cangelos, G, 2014, Dead or Alive: Molecular Assessment of Microbial Viability
https://aem.asm.org/content/80/19/5884 DOI: 10.1128/AEM.01763-14

Hot! Hot! Hot!

November 6, 2017

Last week, three of us poured our energy into designing a proper thermal compost pile. Today was the critical third day after the initial turning of the pile. Did the center stay above 131 degrees F? Drum roll. Both thermometers read 155. We did it!

A proper thermal compost includes the following procedures:

All parts of the compost must have adequate moisture and reach threshold temperatures,
either:
160 F for one day
150 F for two days, or
131 F for three days.

These temperature requirements are necessary to kill human and plant pathogens, insect pests, and weed seeds. If your pile does not heat up or, it does not heat after turning, the problem is often due to lack of nitrogen in the recipe and/or the pile cooling down too much from turning.

During our first try last May, the pile did not heat up enough after we laboriously turned the insides to the outsides and the outside materials to the inside with garden forks. What an effort. No wonder no one turns a compost pile.

the-turn-w-steam-20171103_091219_hdrWe came up with a new trick this time and it worked. Welcome to the stage … mesh onion bags!

Kate and Ruth carefully mixed all of the ingredients and then stuffed them in the red bags. The bags that would be in the hot center of the pile were laid inside the chicken wire frame standing straight up. In contrast, the other half of the bags, those that filled the cooler perimeter, were laid in horizontally. From the bag orientation, we could tell which compost had been in the hot center and which had not.

Sun, Nov 19, 2-4, Work Party
Sun, Dec 17, 2-4, Work Party
Sun, Jan 21, 2-4, Work Party

The center bags heated up in no time and remained at 150 F for two days. Time to turn the pile. All the bags surrounding those hot bags went to the middle of the pile and the hot bags came out to surround those new center bags. The turn took two volunteers 10 minutes and was not the least bit backbreaking.

What we accomplished:watering-after-turn-sm-20171103_091801_hdr
1) the surety that all parts of the compost heated up adequately,
2) only one turn was necessary, and
3) anyone could help turn the compost pile without needing to be strong as an ox.

The whole process took seven days. Now the pile will cool to ambient temperature and evolve over the next several months. We will make good use of the finished compost next spring.

tarp-is-last-sm-20171103_092558_hdrHow can we improve upon our new idea? We would like to work with bags made from natural material instead of polypropylene. Let us know if you have an idea.

Ruth

Day of Dragonflies

July 7, 2013

Today, I was thigh deep in Green Lake, helping Friends of Green Lake (FOGL) haul Eurasian Watermilfoil out of the water. (Eurasian milfoil is an invasive non-native plant.)

Dragonflies were everywhere and some were quite large, though not as big as this one pictured Dragonflieshere from Butchart Gardens. (Possible sound wall art?) The dragonflies were landing on the mat of milfoil, downed tree branches and blue-green algae. I was removing some of their perch. Speaking of perch, I freed one fish that was tangled in both milfoil and knotted fish line – yet another reason for milfoil removal.

Watermilfoil is excellent compost (http://www.apms.org/japm/vol16/v16p24.pdf) so Nancy took five bike trailer loads to the orchard. The material will work well under the cardboard, especially since leaves are scarce at this time of year. I spoke with several people who were walking the lake and one man said that milfoil washes up to the upper east corner of Lake Washington, near where he lives. He said he has hauled milfoil to his garden and he noted that it took about a year to break down.

Save The Dates
1st Public design meeting Aug 18. 2nd meeting Sep 28 – Both at the Orchard.

Today at the lake, I also heard a loud commanding boot camp instructor. Hmm… I said to myself, I know a good boot camp class that is free: our next sheet mulch party, Sunday, July 14, 2-4 pm! (All are welcome and only one job requires brute strength.)

Other important news: Thanks to the hiring committee of Justin, Nancy and Pam, we hired Barker & Associates as our Landscape Architects (LA) for the upcoming Orchard community design process. Jackie Cramer will be on the team as the permaculture expert.

We can sure use more helpers, especially for Nancy, who is in charge of hosting the three public meetings at which the community design process will unfold. Please give us a call or send an email. Also, keep your eye on the calendar page of this website.

Thank you to Aaron for designing our brochure and 062113 Aaron's Heart smadopting Alex’s three tree circles (photo at right). Thank you to Melany for providing professional signs for the trees! Thank you to Justin, Nancy, Joan, Jennifer & Marcus, Max and Dana for their excellent sheet mulching Sunday, June 30.

063013 work party crew sm JH

Finally, there is interest in hosting Seattle Night Out (Against Crime), at the Orchard, Tuesday evening August 6. We love the idea but many of us are busy with the Neighborhood Matching Grant responsibilities. Please speak up if you are willing to help coordinate. A volunteer who will organize entertainment has already stepped forward.

Ruth