With our very sandy soil (CEC = 4 to 5), organic matter is extra essential. Sandy soil is notorious for rapidly leaching nutrients and drying out fast, but organic matter can hold onto nutrients and absorb water like a sponge. This sorta makes up for sandy soil’s missing clay content.
So check out our super duper chart! It shows the eight fields under our care (40 acres total), our management decisions, and organic matter data from soil tests.
It’s not wise to think a single data point is accurate, but series of soil tests can show general trends.
Differences between Scott and Neighbor Fields
From 2010 to 2012, the average percent change in our fields (Scott) is over 50 percent! This makes us super happy. That’s a lot of sequestered carbon in just two years. Since May 2009, the average percent change is over 100 percent, but I’m wary of including the 2009 test because it’s different than the other three Logan Labs tests. But, organic matter in the low 1% range corresponds to how poor the soil was when we first got here.
The average percent change in our neighbor’s fields (the three with data) is over 20 percent, still good! The difference is probably explained by our neighbor’s fields not being in grass like ours are/were, and maybe our August 2011 amateur rotovating (still makes me cringe to think about it) burned out some soil carbon.
The Three Best Fields
Like I said above, it’s not good to concentrate on single data points, but the organic matter percentages correspond to our perceptions of field quality. We’ve had a feeling for a while that Scott West, Scott Middle, and Neighbor North and West are the fields that need alotta help. In contrast, the three fields showing organic matter over 3% make me say “DANG!” when I bush hog them. The bush hog works hard and slows the tractor’s RPM. They produce a lot of biomass for sure. Our McCarthy field was the one I photographed this summer. The pictures show very strong and healthy plants even under drought and heat stress, something I attributed to compost, which might be true.
More Organic Matter from Cover Crops?
The test data are mixed (and too few) to see if the cover crop fields stored more organic matter than the grass fields. (We have no livestock and don’t sell hay.) I know for certain that our cover crops grow way more biomass than our grass produces, so maybe the difference will show up on our future soil tests.
We’re going to spread this year’s batch of compost, foliar spray liquid fish & seaweed, and broadcast calcium and micronutrient fertilizers. We haven’t decided what we’ll plant on each field this spring. We’ll soil test again next fall to keep accumulating data. But all in all, things are looking up for our rapidly improving soil!