Who Knew? Cover Crop Cocktails are Commune Hippies

I came across this cover crop article the other day that featured quotes from Dr. Jill Clapperton. Dr. Clapperton was very influential to me – I heard her speak once in fall 2011, and I really clued into everything she said about diverse mixes of plants collaborating with soil life to rejuvenate soil. Everything clicked. I came home and decided to limit tillage and started planning my first big cover crop cocktail for planting in spring 2012. And I went crazy with the first cocktail – 20 varieties of seed! And then, the dreadful drought hit and made summer 2012 unforgettable for most farmers in the eastern half of the U.S. Corn fields around our farm were “fired” (brown and crispy). But our cover crop cocktail stayed green. How was it doing that? I gleefully wondered.

hippiesJill Clapperton: “With a diverse cover crop all roots are crossing over below the soil surface touching each other and they are sharing things. If the crop combination is compatible they are sharing nutrients and water. That is probably why a mixed species stand survives and does so much better than a single species stand.”

Yuck. Plants are behaving like a bunch of commune hippies, sharing stuff and whatnot. Not competing and killing each other like they should – water and nutrients are scarce resources!

Dr. Clapperton says sharing happens in the roots. I think this is fascinating, and it opens up even more questions:

  • What makes a crop combination “compatible”?
  • Are the plants doing the sharing, or are soil microbes & bugs doing the work, acting as exchange agents between plant roots?
  • Why/how did plants become compatible instead of competitive, especially under stress?

I’m looking forward to learning way more about this. How ’bout you?

Healthy sorghum in cover crop cocktail.

Healthy sorghum in cover crop cocktail.  July 2012, 3 weeks of high temps and no rain.

Save Farmers: Eat Your Cowpeas and Millet???

Cowpea plants flowering and starting to make seed - best time to kill for max benefits to soil.

Cowpea plants flowering and starting to make seed – best time to kill for max benefits to soil.

I just finished reading famous chef Dan Barber’s article in the New York Times, “What Farm-to-Table Got Wrong”, and I’m left with a major “HUH?” I don’t get it. Barber argues that to fully support small eco-farmers, we need to do more than purchase their food crops: We also need to purchase all the cover crops that support the food crops.

Barber purchases emmer wheat for his restaurant from a small farmer. When Barber visited the wheat farm, he saw different cover crops growing for several seasons to prep the soil to produce delicious emmer wheat. Problem: the farmer gains no income from the cover crops. Remedy: purchase and eat the fruit of the cover crops – cowpeas, millet grain, etc. to make the cover crops profitable to the farmer.

HUH? I’m all for farmer profits, but doesn’t selling a cover crop negate the purpose of a cover crop – to improve the soil?

Akin to humans vacationing at a luxurious spa where they avoid stress and enjoy good food, cover crops are fabulous spa treatments for farm fields. All the plant biomass (roots, stalks, leaves) stays on the field. Nothing is taken off and sold. And, all the biomass feeds soil critters, eventually turning into new productive topsoil. Everything stays put. Ahhhhh… so invigorating!

Cover crops, like almost every plant, also feed and stimulate soil life in real time, while the cover crop is growing. It’s a symbiotic two-way street – plants send sugary photosynthesis products out their roots to attract and feed beneficial soil critters, and in turn, soil critters package and deliver desired nutrients to plant roots. As plants grow, the relationship scales up, which eventually creates high-functioning soil, the class of soil that can grow high quality, drought-resistant plants with little fertilizer (google farmers Gabe Brown and Dave Brandt).

Millet plants starting to make seed - kill it now!!!

Millet plant starting to make seed – kill it now!!!

But problem: I’ve heard that when plants start to make babies (seed), they shut off the two-way street relationship with soil life. Plants need to dedicate almost all their energy to making seed. Soil life no longer gets fed. Farmers know the best time to kill cover crops is right before seed set – farmers can reap the cover crop’s max benefits AND immediately plant their profit crop into soil that’s still amped up.

My point is: millet plants are a great cover crop. But removing and selling millet seed (think of all the soil nutrients in that seed!) dilutes the power of the cover crop. It’s like going to spa to get some much-needed R&R, but the spa turns out to be loud and stressful. It’s a big missed opportunity.

Your Future Favorite Sci-Fi Horror Movie Will Star Soil Bacteria.

Fruiting body of Myxococcus xanthus (Picture: Max Planck Institute for Developmental Biology)

Fruiting body of Myxococcus xanthus (Picture: Max Planck Institute for Developmental Biology)

Screenplay writers looking for the next sci-fi blockbuster should look to soil microbes for inspiration, especially the very horrific bacterium Myxococcus xanthus.  Far different than peacenik single-celled bacteria we all learned about in school, M. xanthus is a social bacterium that communicates and organizes itself into multi-cellular, three dimensional structures made up of thousands of cells that hunt for food and survive harsh conditions together.   Like a wolf pack, the structure travels through topsoil as one unit searching for prey.  When the structure encounters potential prey, it works as a group to secrete powerful enzymes into the environment to kill and digest the prey outside the structure before drawing in the digested nutrients.  According to Rice University scientist Oleg Igoshin, these enzymes are potent antibiotics that kill other species and chew up prey proteins into small segments.  Check out this microscopic video showing 100,000 cells of M. xanthus digesting 10 million cells of E. coli.

Imagine if we saw this social-self-assembly-enzyme-spewing behavior exhibited by large animals that are familiar to us?  Freaky!  And M. xanthus is just one out of 10,000 to 50,000 microbe species contained in just one teaspoon of soil.  Soil is amazingly complex and so much more than the dirt that holds up our corn and soybean plants.  It’s a living, breathing, violent ecosystem and one we still know relatively little about.  In my opinion, soil’s complexity and humanity’s lack of knowledge calls for caution in soil treatment.  For our farm, we’re exercising caution through little to no tillage and no “cides” (pesticides, fungicides).  Best to leave it alone and let all the freaky microbes do their jobs.

Grass vs. Legume Competition – Does the Winner Tell Us Anything?

If you’re the one who’s been reading this blog regularly :), you know that since May 2011, we’ve been planting summer and winter cover crops to improve our dusty, depleted soil.  We’ve never planted just one species – it’s always been a mix of at least two different plants – at least one grass and one legume.  (For newbies, legumes work with soil bacteria to make their own nitrogen.  Examples:  beans, peas, vetch, clover, alfalfa, etc.)

As the soil health gets better & better over time, I think I’m seeing some of the fields expressing their healthy transition through the types of plants (grass vs. legumes) that are growing.  Could I be seeing things and reading way too much into them?  Quite possibly!  But it’s interesting to think about… at least for me!

Take this picture of our neighbor’s east field from May 2012.  It shows what we lovingly remember as our 3-foot tall “vetch jungle mat”.  But wait… something is missing.  Where’s all the rye we planted with the vetch?  Virtually no rye germinated.  What you see in this pic is 100% vetch.  We were happy to get vetch’s wonderful weed-blocking services and all that free nitrogen.  But we wondered… what in the world happened to the rye?  Why didn’t it germinate and grow?

May 2012.  Neighbor's east field.  Vetch jungle mat.  No rye germinated.

May 2012. Neighbor’s east field. Vetch jungle mat. No rye germinated.

Now check out this pic of the same field one year later, in May 2013.  We planted a winter cocktail of radishes, oats, cereal rye (we’re optimists), austrian winter peas, crimson clover, and lupines.  Both grasses – oats and cereal rye – germinated and grew stupendously.  The oats died in January from hard freezes, but you can see lots of healthy rye (looks like tall, skinny wheat) growing in this picture, along with crimson clover and peas (legumes).  We never put nitrogen fertilizer on this field, so why the extreme change in grass growth in just one year (non-existent to beautiful)?

May 2013.  Neighbor's east field.  Cereal rye growing well with legumes (crimson clover and peas).  Yellow flower is year-old mustard, planted in May 2012.

May 2013. Neighbor’s east field. Cereal rye growing well with legumes (crimson clover and peas). Yellow flower is year-old mustard, planted in May 2012.

Curious, I googled “grass legume competition” and found lots of information and research results, but no solid conclusions.   Many research studies tested grass/clover pastures at different nitrogen fertilization rates and found that more grass grew with higher nitrogen.  Makes sense, because grass loves nitrogen and clover can make its own.  Some researchers documented that added nitrogen made pasture grasses grow so big so quickly that the clover got shaded out.  But, other studies found that different mowing heights and times resulted in the same grass vs. clover effects.  So the precise effect of nitrogen on grass vs. legume competition isn’t clear, but it’s generally accepted that grass loves nitrogen.

We subscribe to Acres USA for the eco-farming ideas.  Many wise old timer farmers contribute to that magazine, and I’ve read from them that legumes are “rescue plants”.  Meaning, it’s hard to get grass to grow well on poor soil, but legumes will germinate and grow well enough on bad soil and will eventually contribute some nitrogen to the soil, enabling grasses to grow better.

So IF legumes are rescue plants AND grasses grow really well with good nitrogen but legumes could take it or leave it, the two pictures of our neighbor’s east field might tell a story.  Maybe the 2012 vetch grew like crazy and the rye didn’t because nitrogen was lacking.  Then, maybe the vetch provided enough nitrogen to get soil functioning so the 2013 grasses (oats and rye) could grow.  I could be dead wrong in drawing these conclusions, but maybe not.  What do you think?  Anyone else out there have thoughts or experience with grasses competing with legumes?

Thanks, Year 2013, for the Extra Soil Organic Matter!

Ho ho ho Happy Holidays!  According to our 2013 soil test results, organic matter has increased again in most of our fields.  As I’ve mentioned in many previous posts, organic matter is extra important for our sandy soil.  With very little clay content, our soil can’t hold many nutrients, not enough to support plant health anyway.  So we’re depending on organic matter to do that job, plus hold water, improve soil texture, provide homes to soil life, etc.  Put simply, organic matter is the keystone to improving our worn-out soil.

Here’s the 2013 update to our chart.  It shows what we’ve planted in each field, plus any tillage, compost or lime applications.  The sparkline graphs at the bottom make it easier to show organic matter trends across the different fields.  They show where each field’s organic matter percentage started in 2010 and ended in 2013, relative to the other fields.

Organic Matter improvement from soil test result data. Click to enlarge.

Organic Matter improvement from soil test result data. Click to enlarge.

At this point, it’s hard to detect a pattern.  

We’ve left two fields in pasture grass (Scott West & Middle) and planted cover crops in the six other fields.  Back in 2010, after getting discouraged from looking at very dull and lackluster pasture grass, I chose to switch some fields to cover crops.  I thought cover crops, because of their huge biomass growth, would result in much bigger increases in organic matter.  So far, this has not come to pass.  All fields increased in organic matter at about the same rate.  Scott West had the biggest increase (87%), but it also started in the poorest position.  The two fields with the smallest increases (31% and 27%) started with relatively high organic matter in 2010.   Scott McCarthy is the field we always refer to as “our best field”.  Plants grow amazingly lush and healthy in this field.  It has the highest 2013 organic matter (3.5%).  Also, its phosphorus levels are four times higher than the other fields.  This field is located next to the old “main house”, so possibly a barn was located here in years past (animal feeds & manure are high in phosphorus).

In summary, there are way too many variables here!  Plus, imagine all the opportunities for sampling error while I was pulling soil samples in the fields.  More data points are needed.

We’re happy that all fields have more organic matter under our management.  We’d love for all fields to get to 4 or 5% organic matter, so they’re about 2% short right now.  With our climate and soil content, 4 to 5% would get our soil to that sought-after moist chocolate cake consistency so indicative of very healthy soil.  We’ll see what the 2014 soil test says.  Happy New Year!

Are Summer Cover Crops the Best Soil Builders?

Why is summer a fabulous time to build soil?  Because the best cover crops for restoring soil love hot weather!  Summer plants, like sorghum sudangrass and sunn hemp, grow giant-like very rapidly and contribute tons (literally) of plant biomass and root mass to the soil.  Winter cover crops will always be extremely important, but they’ll never match the biomass-generating potential of sorghum sudangrass and sunn hemp.

Sunn Hemp and Sorghum Sudangrass

Sunn hemp is a tropical legume that contributes organic matter to the soil, produces nitrogen, and grows well in low-fertility soils (perfect for our degraded farm soil).  And according to the SARE cover crop guide, sorghum sudangrass is “unrivaled for adding organic matter to worn-out soils”.  Exactly what we need!  Both sunn hemp and sorghum sudangrass have the potential to produce 5,000 pounds of biomass per acre, so it’s safe to assume this cover crop grew at least 2 tons of biomass per acre for us.

Healthy 6-ft tall sunn hemp and sorghum sudangrass on July 31, 2013.  Planted on June 1st.

Healthy 6-ft tall sunn hemp and sorghum sudangrass on July 31, 2013. Planted on June 1st.

Giant Cover Crops Provide Giant Benefits

Growing carbon-rich summer biomass is so central to soil restoration because carbon is usually the primary limiting factor of degraded farm soil.  When the hugely tall plants get mowed down, all that high-carbon, coarse mulch protects the soil surface and stimulates a wide array of beneficial life to set up shop and do their soil-service jobs.  Soil bugs eat the mulch and poop out nutrient-loaded pellets (free bio-activated fertilizer).  Earthworms and other critters distribute the mulch through the soil profile, which transforms into much sought-after soil organic matter.

And the roots!  The roots are just as crucial, maybe more so.  During the growing season, roots leak sugary photosynthesis products (exudates) into the soil to stimulate beneficial soil life.  These sugary (carbon) exudates work their way through the soil life food chain and eventually become soil organic matter.  And when a cover crop grows 12 feet tall, the roots likely go down 12 feet, pumping carbon into the entire soil profile and sucking up calcium, nitrogen, and other nutrients that had leached out of our very sandy topsoil.  These nutrients end up in the plant biomass, which is now back on the soil surface and getting munched into new, top quality topsoil by soil critters.  These are just a few of the many benefits provided by a 14-week summer cover crop!

How We Managed

Planting:  We purchased Cover Crop Solution’s Homestead mix and planted it in early June on our worst fields, Scott east and neighbor west.  Seeding rate was 15 lbs per acre.  (Our best fields got a different summer cover crop and then were planted to a perennial pasture mix in August.)

Growing:  By the end of July, the cover crop was 6 to 8 feet tall and green and lush.  The previous cover crop was our legume-heavy winter cocktail, so the sorghum sudan was probably loving all the nitrogen the winter legumes pumped into the soil before they died in late May.  By mid-September, the sorghum sudan was up to 12 feet tall in places.

Mowing:  We didn’t mow until very late, September 21st.  Mowing in early August is a good idea for stimulating more root growth and making the end-of-summer management a lot easier (see pg 108 SARE cover crop guide).  But, we chose to do only one late mowing because of laziness and weed suppression.  In our ongoing no-till cover cropping scheme, we haven’t used any herbicides, and weeds have become a problem.  So we wanted to leave the cover crop tall and thick for as long as possible to shade out and suppress weeds.

Busting the sorghum sudan down to the ground required two mowings:  a first rough cut with the bush hog in the highest position, and a 2nd finishing cut with bush hog in lowest position.  If you do this, watch out for thick sorghum sudan canes ripping off tractor wires during the 2nd cut!

Mowing 12-ft tall jungle forest of sorghum sudangrass and sunn hemp on September 21, 2013.  Pic taken during 1st rough cut with bush hog in highest position.  Look at all that mulch!

Mowing 12-ft tall jungle forest of sorghum sudangrass and sunn hemp on September 21, 2013. Pic taken during 1st rough cut with bush hog in highest position. Look at all that mulch!

Next Cover Crop:  We planted a winter cover crop of cereal rye, peas, and vetch on October 5th.  We rented our county’s no-till drill for planting.  The drill can slice through the thick sorghum-sudan mulch and set the new seed into the soil.

Cereal rye, hairy vetch, austrian winter pea seedlings coming up through sorghum sudan & sunn hemp mulch on October 24, 2013.  Planted on October 5th.

Cereal rye, hairy vetch, austrian winter pea seedlings coming up through sorghum sudan & sunn hemp mulch on October 24, 2013. Planted on October 5th.

With constant signs of depleted soil all around us on our farm, soil improvement is always on our minds.  So it feels very good knowing we’re headed into winter with thick protective mulch on our fields and a nice new winter cover crop growing up through it.  Thanks for reading!

A Fantastic Short-Duration Summer Cover Crop

Three of our fields have improved to the point where we can stop growing cover crops and plant our final pasture grass mix for our future livestock!  These fields have more than 3% organic matter (still not a great %, but pretty good for our very sandy soil), and they consistently produce very lush & healthy cover crops.

Our last cover crop was mature and dying in mid-May.  I want to plant the final pasture grass mix sometime this August so it can grow well this fall before winter sets in.  For summer weed suppression and other benefits, I want to plant something for the summer, but I don’t want to till or apply herbicides to kill it in August before planting the grass mix.   What to do?  How about a short-season cover crop?  Yes!

Many plants make wonderful summer cover crops, but only a few of them (to my knowledge) are short season, meaning they grow, mature, flower & produce seeds within a short timeframe.  Annual plants that are mature will die by mowing.  No tillage or herbicides needed!

I chose buckwheat, sunflowers and oats.  (See my previous post on summer oats.)  Buckwheat matures in seven weeks!  And the sunflowers I chose (Terraza) were 70-day, meaning they flower at 70 days after planting, well within my August deadline.

Bonus:  the sunflowers and buckwheat are beautiful together!  The pic below does not do them justice.  Both have reached over 5 feet tall in some places.   Other benefits include:  great weed suppression, soil texture improvement through buckwheat’s abundant, fine roots, and phosphorus scavenging (getting hard-to-get phosphorus from the soil and putting it into plant available form).  I’m not sure what sunflowers uniquely do for soil health, but I heard they scavenge zinc.

I’m glad the last cover crop for these fields is so pretty!

Buckwheat, sunflowers, oats.  Planted June 1, 2013.  McCarthy field (7/31/2013)

Buckwheat, sunflowers, oats. Planted June 1, 2013. McCarthy field (7/31/2013)