Slide of the Day | Remember to Count: Chemical Fertilizer Energy Inputs Compared to Compost (Typically Applied in Organic Systems)

Slide from Glenn McGourty presentation

Last week I visited Russell Ranch at U.C. Davis for soil health presentations, including those by Kate Scow and her team who have recently documented the dramatic impact of compost in sequestering carbon.

Today, while searching for something else, I came upon Glenn McGourty's fabulous presentation on soil health and vineyards.

We are often told that "sustainable" wine grape growing is the answer to climate change and soil issues, and that because organic certification does not require regenerative practices, it is not as good for the environment.

Nothing could be further from the truth, as, even though the regulations don't mandate healthier soil practices, most organic growers do use compost.

Tillage turns out to be not nearly as important as previously thought (as long as it's just the top 6 inches, according to the Russell Ranch study's experts).

Slide from Glenn McGourty presentation

The slide above shows that, aside from carbon sequestration alone, compost has HUGE benefits when we look at the resources needed to fertilize soils with chemicals.

You can see McGourty's whole slide deck here.

I guess I haven't yet posted anything about the U.C. Davis trip (except on social media) so here's a link to the published version of their compost research from CalCAN.

And as a slide from the presentation last week shows (see below - the vertical bar on the right) there is vast potential for carbon sequestration in the organic farming example where compost is applied.

In recent years, the U.C. researchers have also added a fourth system in which compost is added to conventional plots with cover crops to see how well soils treated with conventional chemicals sequester carbon.

To date, scientists are divided over what the impacts are of using compost in non-organic systems in terms of the impact on carbon sequestration.

Compost study results from Russell Ranch study, published 2019. The compost (organic) system on the right sequestered
far more carbon - about 0.7% per year which added up to 12% over the length of the study, The study has recently adopted a fourth category - which includes compost with conventional farming. Note that cover crops, while they have many virtues, do not aid in carbon sequestration, according to the researchers.