#Soil Carbon in Saticoy

I’ve been doing some reading recently on the topic of soil organic matter, most notably in the book The Soil Will Save Us, by Kristin Ohlson. There’s a lot of discussion about sequestration of carbon in the soil, and what agriculture has done in the past and may do in the future to affect that amount. But much of the discussion relates to large-scale Midwestern farming – rangeland grazing and grain production. It doesn’t speak to Ventura County agriculture. How are we faring?

At our farm, we have had a covercrop program going in our orchard for 10 years, and it made me wonder… was there a good way to see a measurable difference for our efforts? Subjectively, we’ve been very happy with our results. Our program has prioritized erosion control and soil structure. We’ve never worried our soil carbon content. But a big part of a soil’s structure is determined by the organic material within, and organic material is a pretty good proxy for carbon. (Direct measurements soil carbon are apparently expensive and not that reliable.) Since we’ve been trying to add biomass, we must be adding carbon, right?

Out of curiosity, I decided to take a look at some numbers.

We haven’t regularly tracked our soil organic matter, but a fairly recent lab test shows us ranging between 5.5% and nearly 7%. (6.94% to be precise.) Unfortunately, we took no baseline measurement before starting the covercrop experiment, but I was able to find a figure to represent our soil in a “natural” state. According to the Web Soil Survey of the Natural Resource Conservation District, the Pico and Mocho series soils such as those at our Saticoy farm typically have only 2.5 – 3% organic matter.

5.5 to 7% sure beats 2.5 to 3%!

It would seem that we are holding twice the organic matter (and presumably twice the carbon) in our soil that existed in nature. I’m actually not that surprised to see an improvement, although double was unexpected. Orchards, even without covercrop, have much heavier vegetation than would exist here naturally, thanks to irrigation. That plant material that my family has been producing over 130 years is reflected in the organic content of our soil.

I’d love to have figures for other orchards in our area, and better data on our soil circa 2005, prior to the reintroduction of covercrops on our farm. If I were writing a PhD thesis, I’d need more data. But for a farmer looking for validation of his practices, this looks pretty good to me.

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One thought on “#Soil Carbon in Saticoy

  1. Pingback: WORLD ORGANIC NEWS | #Soil Carbon in Saticoy | SaticoyRoots WeblogWORLD ORGANIC NEWS

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