Soil health is a topic of concern among a growing population of agriculturalists and an increasingly vocal public promoting sustainable, managed landscapes. It is also the current focus of a national initiative through the USDA-NRCS to provide relevant and useful information to farmers to improve long-term ecosystem function of agricultural soils. Soil health Key Points from the NRCS may be found here; their Fact Sheets may be found here.
A fundamental tenet of sustainable agriculture is the philosophy that sustainability is underpinned by maintaining a “healthy” soil. While there may be some agreement on the general academic definition of soil health as “…the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, maintain the quality of air and water environments, and promote plant, animal, and human health” (Doran et al., 1996), there remains considerable debate among the soil science community as to how soil health should be measured. The Soil Health Institute, a public-private partnership and the Cornell Soil Health Testing Laboratory are moving the conversation forward at the national level.
To provide geographically specific information on Soil Health in Hawaii, we currently are asking: what metrics comprise the critical factors necessary to develop an organic matter-based soil health index for Hawaii’s diverse, tropical soils? Further, what advice do we provide Hawaii (and Pacific Islander) farmers for management to improve soil health for greater resilience and sustainability of our agroecosystems in the future? First, we visited farmers and land managers across multiple islands with soil under a wide range of current soil health status and land use. These soils were measured for over 25 metrics of soil health. From there, we will reduce those to a few key factors that provide an index of soil health appropriate for Hawaii’s diverse soils, cropping systems, and producers.
Next, we are building a network to bring the Hawaii community together to provide information, soil health measurements, and data monitoring and analytics. Soon, we will demo a technical tool and start a soil health Hawaii project blog designed to inform, engage, and understand the community’s needs as we move forward with our research into soil health and potential carbon sequestration in Hawaii.
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?
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, even when degraded, can range 6-38% 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.
Resources:
Press release for our recent papers on the ecology of soil carbon and need for data synthesis to know the potential for soil management to mitigate climate change.
NYT article on regenerative pasture and soil carbon, Hawaii’s progressive legislation for the Carbon Farming Task Force got a mention near the end!
The Tipping Point podcast on climate justice in the Anthropocene has me thinking about what didn’t work in the European carbon markets, and what might work better this time for Hawaii as we move forward with progressive new legislation meant to combat climate change.
Landscape architects “Leading the Charge for Climate Action”
The Nature Conservancy puts out a new report on soil carbon, stating “Soil carbon projects are laboratories for transforming the agricultural sector to reach sustainable growth, climate change resilience, and climate change mitigation. Soil carbon projects are innovators: for farmers, local communities, as well as investors.” CTAHR, UH Manoa, and Hawaii should be leading the country in putting these ideas into action in support of our island communities.
Crow Soil Ecology & Biogeochemistry Lab 