Soil & Climate Change Mitigation

Author's comment: It's amazing how far I've come in understanding soil science since I first started asking questions in 2012. See blog posts here and here. At the time I was caretaking a couple garden spaces, and little did I know the soils were actually in decent shape (thanks to the efforts of former gardeners). Also six years ago I wasn't making the connection between soil building practices and climate change, nor was I aware of our rapidly depleting top soils. A few years later I was gardening in a newly tilled area with no soil building at all--a great demonstration of the effects of urban development on Seattle Soils. See that blog post here. Fortunately at the time I was in the middle of a "Soils" class so was able to interpret the results of the test. Still I wasn't thinking in terms of climate change mitigation; I'm not sure why but it seems hard to talk about it. In my current garden in West Seattle, I haven't actually taken any soil tests yet. Just by looking at the health of the plants and the color of the soil I am able to determine it's in pretty good form. Of course, soil testing would reveal the fascinating chemistry within it--but it's not the right time of year to yield the best results. So I'll wait for now. And keep building the soil. And researching.

I've been gardening in West Seattle for just over a year. There are some peculiarities about this space, including that it sits in a ravine at the base of High Point, so gets part sun much of the year, and is in a bit of a frost pocket. When I first moved in I noticed a lot of the soil was sandy, which surprised me due to Seattle Soil's reputation of being clay/acid. Which was a good reminder of how much variation exists in any area.  Based on what I learned in the "Soils" class I was aware of soil building practices I could do to remediate the sandy soil, so I focused on that immediately. A couple months ago, I was transplanting some materials and noticed what a year's worth of soil building had given my garden at Tim's. I was so excited I posted a photo on my Instagram:

This gave me a lot of encouragement that with thoughtful effort, I can influence the health of soil in whatever garden spaces I am working in. Almost two years ago I took a "Soils" class at a community college, which opened my eyes to soil structure, chemistry and the formation of tilth. I couldn't believe I had been gardening all those years without this basic knowledge. I've now been coming to learn how the health of plants really begins in the foundation of soil science. However since this field is always changing with new research, I've committed to continuing my education for life on this particular topic, while investigating the microclimates I am working in. In addition, there is the issue  of climate change and how it will influence soil science in the time to come.

Next month, I am moving again--onto a farm on the Olympia Peninsula, and I've been told by the farmers they are working with peat soils. I know very little about this type of soil so in preparation, I've decided to do some research. All I remembered from my "Soils" class was that peat is a carbon sink with a ton of organic matter and poor drainage. Upon learning there are peat soils at this particular farm, a question immediately arose in my mind: should we be digging up peat soils? In the face of climate change--shouldn't we be preserving peat lands wherever they exist? I will begin answering this question only as I start working on this farm, I'm sure.

Peat soils are called "Histosols" per their taxonomy. Here is a nice map of histosols in the U.S. created by the NRCS:

This map suggests to me that the Pacific Northwest is not a region where histosols are usually found. So if we have them in our area, they are probably in little pockets. Also from this map we can observe the percent of histosols in general is very small! According to Soil Society of America, histosols make up only 1% of the world's glacial-free land surface, which makes them very special. International Peatland Society says they make up 3%--but either way it's still a very small amount. IPS believes for the sake of mitigating climate change that peatlands must be properly managed to avoid increasing greenhouse gases (CO2, CH4, etc) and compaction (caused by changing hydrology patterns), while increasing carbon sequestration. I couldn't agree more! I am not sure how to pose this conversation with the farmers but perhaps I can casually bring it up sometime while working in the field.

There is a really nice article in Permaculture News that discusses peat soils (read here). I am not sure what percent of peat this farmland is where I will be working, but I'm assuming the farmers lean more in the direction of realizing their economic benefits--as we've had very little discussion of permaculture practices thus far. I do know they haven't formerly drained their land, so it's possible the percent of peat is not super high--otherwise they wouldn't be able to produce their vegetables (due to anaerobic conditions). And I must also acknowledge the farmers are simultaneously practicing some conservation to maintain natural habitat, particularly along the waterways, and the area for vegetable cultivation is only around an acre (not including pastured animals). I am definitely not trying to imply the farmers are disturbing their peat soils, just that it's possible some of their practices might benefit from shifting into more of a permaculture framework.

The Food and Agriculture Organization of the United Nations (FAO) recommends "paludiculture" practices, which work within the constraints of the peat microclimate. Without disturbing natural hydrology, you can cultivate crops more appropriate for that setting. The FAO also suggests various fodder crops, wood (trees that can tolerate high saturation) and food crops including aronia berry, lotus, cranberry, water chestnut and wild rice. From my perspective this particular bit of land  might provide a great educational opportunity for people in the area on peat soils and paludiculture. In fact the farmers might be able to work with a conservation district or WSU to conduct research, and they could provide workshops on permaculture and paludiculture--peatland restoration and cultivation--for the sake of climate change mitigation. We certainly could use more organizations in the area that are directly tackling issues on climate change.