Even degraded soils in Hawaii often hold a lot of carbon

Perspectives for Hawaii – Reports on scientific papers appear in news feeds and social media, but what do the results mean for Hawaii?  How, or does, it apply?

photo_soil pit with scale

I tweeted about this Yale paper headlining “link between soil and crop yield is valid – to a point”.  An assessment of available crop yield and soil carbon data globally showed more carbon associated with higher yield but only up to concentrations of 2% carbon.

In Hawaii, we’ve measured carbon in some of the most degraded agricultural settings and, at least in the surface soils, the concentration is nearly 2%.  Volcanic ash soils such as those abundant on the Big Island and elsewhere, even when degraded, can range from 6 to 38% carbon.

Does this mean we can’t expect improved yields with climate smart practices meant to increase soil health and promote GHG sequestration in Hawaii?  No.

The authors clarify “Because all locations will have different thresholds of how much a soil property can be changed and what level of a soil property is ‘good’ for that place”.  The value of this synthesis is that it is a quantitative starting point to guide policy and practice to establish targets, but place-based relationships between soil carbon, organic matter, and crop yields must be established.

Carbon comprises about 50% of soil organic matter, which is a central component of soil health.  Organic matter in soil provides substrate for the microbiome that releases nutrients through their metabolic activity, improves water relations, and increases aeration, all of which improve soil health and more.

Hawaii’s soils may have a high starting point for carbon, but they also have high potential to store even more due to deep soil profiles, volcanic ash deposits, and high productivity.  The more organic matter accumulates, and is stored within multiple carbon pools in healthy, productive agroecosystems, the more climate, soil health, and yield benefits may be achieved.

Please see some of our research results on our project page for more details.

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