Page 52 - referenceguide6th_web

LENGTH OF GREEN

Around soil health and conservation, the questions we ask This first map (see previous column) shows, in darkness of
have been mostly about practices, species, or substances. green, the intensity of photosynthesis (NDVI) from July 25 to
Practices such as terracing, buffer strips, strip till; species for August 15 in 2018 for an area just north of Elkhart, Illinois.
CRP seeding or edges; and substances such as plant-available The red marker on the left is in a field where cover-crop ex-
nitrogen, phosphorus, or organic matter. These questions are periments are being tried. The marker on the right is business
important, and they help guide practical action, but there is as usual for the corn belt: short-season annual cropping of
another less immediately visible dimension. This is the flows corn or beans.
and changes of sunlight energy that drive water and carbon
cycling, which together make up the most powerful planetary
force. Our agriculture and land management have changed
and continue to change these flows of sunlight energy in
ways we may not intend or be aware of.

Since the 1880s, our government has spent hundreds of bil-
lions on controlling the rivers in the Mississippi-Missouri
system. Since 1931 our nation has spent hundreds of billions
on soil conservation. Have we been dealing with a symptom
or a cause? According to a U.S. Geological Survey report on
the Mississippi-Missouri basin, precipitation increased 2.1%
per decade from 1949-1997 in the basin, while estimated
total runoff increased 5.5%, some of this not making it to the The above map shows duration of photosynthesis rather than
Gulf because it was held behind dams. The unavoidable con- momentary intensity and is nearly the reverse of the summer
clusion is that the soils of the central U.S. have become in- map. Same area, same markers, this map shows number of
creasingly compacted and less able to infiltrate or store water. days in which photosynthesis was over a threshold (in this
Basin-wide, we do a poorer job of capturing rain where it case, NDVI over .3) The darker the green, the longer soil life
falls, missing our biggest opportunity to capture sunlight is being fed by plant photosynthesis such as root exudates,
energy as water held in covered, porous, well-aggregated soil. and the more chance soil life has to grow and maintain soil
This amounts to a massive sunshine spill and observers point structure and aggregation. The marker on the left shows a
to the flooding of 2018-19 as a bigger ecological disaster than huge increase in the capture of sunlight energy, with cover
the BP oil spill. crops providing a much longer season of plant growth.
Most of us now realize that maximum sunlight capture de- Maps of energy flow can give us additional perspective and
pends on green plants with living roots feeding the soil food- underscore the need for the implementation of soil health
web through photosynthesis, driving the biological carbon principles of soil cover, living roots, diversity, minimize till-
cycle that feeds us all. If we’re going to take responsibility age, and integrate livestock.
for the capture of sunlight energy, it helps to be able to see
it over time. Satellite data can be an asset here. People use By Peter Donovan
satellite data to look at a vegetative index to show crop stress Peter Donovan founded the Soil Carbon Coali-
or predict yields, but we can also ask some different questions tion in 2007 and shortly afterwards embarked on
the Soil Carbon Challenge: soilcarboncoalition.
about energy flow on our croplands, as with these maps: org/challenge. For many years, Peter has written
on innovative natural resource stewards, and
most of his articles can be found on ManagingWholes.com.

“I have been nothing short of super impressed with your com-
pany, from start to finish. I tried to work with someone local but
nothing was available. I found you guys since you had a large
selection of species and carried all non-GMO products.
I called to ask for help with a drill seeder I’ve never used before,
and had immediate help over the phone in real time. I will be
seeding my fields for many years to come and look forward to
working with you guys each and every time. Thanks again.”
Jeremy A - Oregon

52