Archive for the ‘soil’ Category

Human Impact and Hope: This Type of Farming is Extraordinarily Good for the Environment

surviving progressI’ve been watching several environmental documentaries on Netflix.  Whatever the focus, every documentary seems to be built upon the theme of “human impact is horrible for the environment – we just can’t help ourselves”.   It’s hard to disagree with this theme when so many U.S. examples are staring at us in the face – the decimation of 75 million-strong herd of Great Plains buffalo, the 1930s Dust Bowl, the Dead Zone in the Gulf of Mexico, the paving of paradises for strip malls, and on an on.  One interviewed gentleman discussed the impact of cities on the environment but said, “Well, people returning to the land isn’t an option either, because that would result in even more land being destroyed.”

A few years ago, I would’ve been nodding my head in complete agreement.  But now, I know there’s another path.  Humans have the resources to provide extraordinary benefits to the environment – healing the land, reversing desertification, and stopping climate change.  I’m not talking about millions of small farms/gardens.  I’m talking about humans using a very low-tech and often vilified tool:  livestock.

Allan Savory, founder of the holistic livestock management framework, has proven that correctly managed herds of livestock can completely heal the land.  It’s all about time management.  The land is pulsed with very high animal impact for a short amount of time and then moved on.   The herd returns months later after the grass has recuperated.  The herd provides another grazing pulse and is again moved on.  Grazing, intense hoof trampling, and manure stimulate grasses to thrive.  Growing grasses extend their roots deeper into the soil profile and take CO2 from the atmosphere and sequester it into the soil.  Plant roots slough off after each grazing pulse, which puts even more carbon into the soil.  High carbon (organic matter) soils hold water and improve the landscape’s water cycle, which attracts more plant and wildlife diversity.  Land on the brink of desertification is restored to beautiful bio-diverse savannah that sustains human communities.  What work is more noble than this?

Check out this short video of Allan Savory explaining the process and proving that it works.  This video is the longer version – very worthwhile watching.

U.S. folks like Greg Judy are using Savory’s principles with management practices called mob-stocking.  This video is very inspirational and demonstrates how land can be amazingly improved via high intensity livestock grazing.  At the end, Greg Judy states that mob stocking can be scaled down all the way to two animals – good news for our small farm.

The housing collapse has delayed our plans for livestock farming for a disappointing several years now.  We’ve been trying to make the best of the delay by cover cropping to improve our farmed-out soil.  The organic matter has increased by 1 to 2 percentage points, and we feel super good about that!  But, we can’t wait to quit our desk jobs and get started with high intensity grazing and watch our soil improve even more.  Thanks for reading!

High intensity grazing improves land.  Herd grazes for short amount of time, then moves.

High intensity grazing improves land. Herd grazes for short amount of time, then moves.

Happiness! Our Soil’s Organic Matter is Growing by Astounding Amounts

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.

Progression of the 8 fields under our care from 2008 to 2012.

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.

Upcoming Plans

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!

The Ultimate Winter Cover Crop Cocktail – and Why We Planted It

We planted a big mix of winter cover crop seeds on 29 acres on September 14, 2012.  This was our fourth consecutive cover crop planting.  Faced with delay in full-time farming plans and getting livestock, we’re trying to use the time wisely and improve our burned-out soil so it will make high quality grass for our future livestock.  Planting cover crops is essentially “Plan B” farming for us.  And yay, it’s working!

Winter Cover Crop cocktail seedlings 2.5 weeks after planting. Oats, tillage radishes, lupine, winter peas, cereal rye.

How Our Soil Needs to Improve

We’re located in Southern Maryland, close to the Potomac, on very sandy soil.  Charles C. Mann’s new book, 1493, has a map of the Eastern seaboard titled “Deforestation of America, 1500”.  Our farm is clearly located in the large coastal area that was cleared by the Eastern Indians for farms and villages probably 500 to 600 years ago.  This history, combined with centuries of hard tobacco farming, explains why our soil is so poor.  So we have a lot of work to do in the soil improvement department!  And we’re using plants (cover crops – nothing is removed from the field) to help.  Here’s our wish list:

  • Double Organic Matter:  Soil tests say it is barely 2%.  We want 4%.  We know this takes time, and we’re using particular plants that have huge root systems to help.  All plants ooze sugary compounds out of their roots to attract a beneficial microbe community, and some do this more/better than others.  The root exudates are complex forms of organic matter, the roots themselves will eventually decay into organic matter, and microbes help speed up the growth and decay cycle.
  • Chocolate Cake!  Yummm… but I’m talking about soil structure.  We want dark, loose, crumbly soil that smells good.  Large pore spaces let air and water percolate through and provide a luxury living space for those essential soil microbes and bugs.  When we first got this farm in 2008, the soil was depressingly dusty and crusty.  The soil structure has improved significantly – we now see nice aggregates – but we still have a long way to go.
  • Big Fat Adult Earthworms:  I have sadly never ever seen one of these in our fields.  We are thankful to now have earthworms (we didn’t in 2008), but they are small and skinny.  Adults with orange collar bands reproduce and are an indicator of good soil.  We are planting particular cover crops that entice the big guys.

    Our soil structure in September 2012. Improving aggregation but still not chocolate cake.

The Ultimate Winter Cover Crop – Explained

Following on our good experience with our summer cover crop mix (cocktail), we chose a winter mix of some of the best plants that meet our wish list items:  Austrian Winter Peas, Oats, Cereal Rye, Sweet Blue Lupines, Crimson Clover, and Tillage Radishes.

Winter 2012 Seed Chart – rates and prices

Rye and Oats:  These cool-season grasses have large root systems where soil microbes and bugs can hide out over the winter.  In the spring, rye’s growth will really take off and produce good, lignified (carbon) biomass.  The mowed clippings will make great mulch to protect the soil from hot summer temps.  The microbes, root masses, and high carbon mulch will all work to boost soil organic matter.

Legumes:  This will be our first experience with lupines, Austrian winter peas and crimson clover.  We inoculated these three to give them the best chance to produce nitrogen for the soil.  On top of the N benefit, this site says lupines have an aggressive taproot that will improve the lower soil profile.  Crimson clover has fine roots that help build a mellow soil structure (chocolate cake) and attract soil microbes.  I’ve heard that winter peas might be one of the best plants for mellowing soil, and they provide good amounts of tender biomass in the spring.

Brassicas:  Tillage radishes are mighty soil-moving machines.  They drill down into the soil profile and will even root down past compaction layers, opening up the deep soil to let air and water percolate through.  Our very sandy soil doesn’t have big compaction problems, but getting plants that go that far down – typically over 30” – is all good for any soil.  Big fat adult earthworms are also strangely attracted to these radishes!

Big adult earthworms feasting on decomposing tillage radish. From Steve Groff’s Cedar Meadow Farm

What’s Next

We’ll mow-kill this cover crop in late spring when most of it is flowering.  Depending on how our farm plans are working out, we’ll either plant our last cover crop or our final pasture grass mix.  I’ll also be posting on our Fall 2012 soil test results.  I’d like to see if any cover crop benefits show up on soil tests.  Stay tuned!

What Extreme Drought? Our Cover Crop Cocktail Didn’t Notice

What a tough summer!  Our farm experienced the 2012 extreme heat and drought that broiled most U.S. farmland this summer.  Nearby farms received okay amounts of rain, but several good rainstorms split and went around us on all sides this summer.  Up until the fabulous 3 inches of rain we received last weekend, about 1.5 inches fell on our farm from June to August, and we’re used to getting 2 to 4 inches every month.  Needless to say, our cool season grass pastures went completely dormant.  The grass was ugly brown and very crunchy.

Drought-Resistant Cocktail

On the other hand, our summer cover crop cocktail did quite well!  We got some good education by watching the cocktail respond to the heat and drought.  The drought did decrease biomass production – the sorghum and millets stopped growing and never got taller than hip high – but foliage maintained a good enough green color even during the strings of 100-degree temperature days.  We will definitely plant diverse mixtures of brassicas, legumes, and warm season grasses for summer grazing for our future livestock.  It’s drought insurance!  And the mixture seemed to work together to survive the drought.

Ranking Best Plant Varieties

In order of best drought resistance, here are the plant varieties that did well on our farm this summer:  Mustard; turnips; sunn hemp; sorghum; soybeans; cowpeas; millets; sunflowers.  I didn’t include dwarf essex rape and buckwheat because they were already mature and setting seed when the drought hit.  Alfalfa and yellow sweet clover remained small, but will probably grow well this fall – I believe this fits their normal life cycle.  Phacelia did not seem to survive the drought.  I did see some safflower that looked good.  I didn’t see any hairy indigo, but I might be mistaking it for a weed.  We do have our fair share of summer weeds!

Late August summer cover crop cocktail after mowing in late July.

This pic shows the cocktail a few days after our recent 3” rain soaker.   The cocktail is now about 18” tall.  We mowed it in late July due to marestail weed pressure. Mowing seemed to stimulate the cocktail.  Mustard, turnips, sunn hemp, sorghum, cowpeas, and millets all started re-growing, even at the height of the drought.  Everything greened up really nicely after the rain, but the mustard and turnips have some stinkbug visitors.  They are getting de-juiced by harlequin bugs.   This shows our soil still has a ways to go before it can support complete plant health.

Cocktail Evaluation

Overall, we’re really glad we planted the cocktail.  Based on cocktail plant density and diversity and healthy green growth during extreme drought, we believe the cocktail provided many more soil health benefits than our existing grass pastures.   Our grass went completely dormant, and dormant grass doesn’t sequester carbon and feed soil life like green growing plants do.  Admittedly, we are lacking the very beneficial animal impact, so our grass would have done better if we had a nice rotational grazing herd.

Even during the drought, the cocktail sucked up and held onto soil minerals that will fertilize future plants, produced biomass that will become nice mulch this winter, and sequestered sugary carbon compounds as it stimulated and fed the soil life below ground.  Also, the cocktail’s legumes produced nitrogen that will be released for subsequent crops, as shown by this picture of our sunn hemp root nodules.

Nitrogen-producing nodules on sunn hemp roots.

What’s Next

We’re getting ready to plant a winter cocktail in early September.  It will be a mix of oats, cereal rye, Austrian winter peas, sweet blue lupin, and tillage radish.  We’ve decided to rotovate an additional five acres of our grass pastures, and will plant the cocktail there too, with additional varieties of vetch and turnips.  We hope that the cocktails will continue to keep soil minerals available to plants, increase organic matter, and stimulate soil life, so when we are able to quit our full time desk jobs we’ll have some amazingly fertile soil that will grow fantastic forage for our livestock.    Thanks for reading!

Our Summer Cover Crop Cocktail! Purpose, Seed Mix, Cost, and Method

We’ve got worn-out farm soil, and we’re trying to figure out the best, fastest way to bring it back to life so we can have very high-quality pasture for our future livestock. We’re convinced that diversity is key to rejuvenating soil. This post explains why and how we planted our summer cover crop cocktail.

Our summer cocktail seed mixture going into the no-till drill.

What is a Cover Crop Cocktail?

A cover crop cocktail is a big mixture of plants. Most cover crops contain just one or two varieties of plants. A cocktail contains many more. Farmers plant cocktails in order to capitalize on the synergistic effects of all different plants working together. Any cover crop is fantastic for soil health because nothing is taken off the field. All the biomass, roots, minerals, vitamins, and most of the carbon that plants accumulate during the growing season gets returned right to the soil in a much better, much more available form for the next crop to use and thrive. Cover crop cocktails amplify these benefits by adding DIVERSITY.

Why a Cover Crop Cocktail is Perfect for our Farm

Our soil’s most limiting factors are lack of organic matter (carbon) and biology. We have very few earthworms, even after 3 years of perennial grass. Organic matter is barely 2%, and it should be at least 5%. Compost and humates are great for adding organic matter to soils, but nothing sequesters carbon like a healthy plant, and cover crop seed is cheap!

Managed correctly, cover crops are guaranteed to add carbon to the soil, and DIVERSE cover crops are guaranteed to add lots of different carbon compounds to the soil via unique root exudates. Different plants leak different root exudates in order to attract particular segments of soil biology that help the plants thrive. Plants modify their environment. With a field full of diverse plants attracting diverse biology, the field can begin to accumulate all the needed components of a very healthy and fully functioning soil system. A soil system like this grows exceptional (nutritious and tasty) crops on less fertilizer and sequesters soil carbon (organic matter) like mad!

Our seed cocktail chart, click to enlarge.

Twenty Varieties of Seed!

I’m kinda embarrassed – we went a little crazy with our cocktail mix. Click the chart to see all the varieties we used, sources, and cost. We ended up with about 70 pounds of seed per acre (probably way too high) with 29% warm season grasses, 37% legumes, 14% brassicas, and 20% broadleaves by weight.
Warm Season Grasses: Big biomass creators, leak lots of carbon, associate with beneficial mycorrhizal fungi to sequester even more carbon. Varieties: sorghum and millets.
Legumes: Fix nitrogen (inoculated), associated with both mycorrhizae and benefical rhizobium bacteria. Varieties: cowpeas, soybeans, hairy indigo, sweet clover, alfalfa, sunn hemp.
Brassicas: Instead of associating with symbiotic bacteria and fungi, brassicas leak harsh acids that cleave off phosphorus and other minerals. For some reason, the acids really attract earthworms and other VIP soil animals. Varieties: camelina, dwarf essex rape, mustard, turnips.
Broadleaves: Highly associated with beneficial soil fungi, flowers attract beneficial pollinators and add to above ground soil diversity. Varieties: sunflowers, buckwheat, phacelia, herbs, safflower, chicory.

Pasture seeding – drilling cocktail seeds into existing pasture. Grass about 8″ high.

Cost

At $77 per acre, we didn’t do a good job at controlling cost. I’ve seen cocktail examples online around $30 per acre. I’m sure these cheaper mixes contribute great benefits too. Our mix does contain a few expensive perennial varieties for our future pastures, such as sweet clover, alfalfa, and chicory. If we were planting a row crop after this cocktail, we wouldn’t include these hard-to-kill perennials. So some of the $77 per acre will continue into future years.

Method

We rented our county’s no-till drill to plant the cocktail mix into 40 acres at a 1-inch depth.   We planted the weekend of May 18th.  Half of the acres were our own pastures, and the other half were our neighbor’s acres where we previously planted rye and vetch. For our pastures, we planned to rotovate to kill the perennial grass, but we ran out of time, became more interested in no-till methods because of this, and wanted to experiment with pasture seeding to see how the seeds came up. Also, reseeding perennial grass is expensive.

The drilling was easy, but mixing the seeds was a whole lotta work! We didn’t account for this beforehand. All the legumes needed different Rhizobium inoculants, and we did that in big bins. We also inoculated the grasses and broadleaves with mycorrhizae. We did a giant mix (all seeds went into the drill’s large bin) for each of the seven fields and filled the drill per field. We used an excel spreadsheet chart to get the right ratio and weight of seeds for every field.

Results

We got nice rains after planting, so the seeds germinated really quickly. Yay!!! The buckwheat and brassicas were up in five days, then came the cowpeas, soybeans, and sunn hemp. Millets came up after about 10 days. It’s now three weeks after planting, and the cocktail is nearly a foot tall in our neighbor’s fields. In our grass fields, the cowpeas and soybeans are just starting to rise above the grass height. The brassicas are following them. I’ll post an update later this summer. Thanks for reading!

The cocktail line-up coming up nicely through mow-killed vetch mulch. Brassicas, sunn hemp, cowpea, millets, buckwheat, soybean. Two weeks after planting. Neighbor’s field.

Soybean and cowpeas coming up in our pasture. Two weeks after pasture-seeding with no-till drill.

Top Five Pros and Cons for Rye & Vetch Cover Crop in Veggie Gardens

Cereal rye and hairy vetch cover crop. Five feet tall 4/20/12

Not too long ago I was one of those people who knew a lot about plants but very little about soil.  I’d leave my veggie beds bare for the winter, not knowing what that meant.  After learning about soil’s needs, I started planting cover crops in 2011, and I’m so glad I did!

In late summer and fall of 2011, I planted cereal rye, a cool-season grass that makes rye grain, and vetch, a viney legume, in all of my veggie beds.  I inoculated the vetch seed with the nitrogen-fixing Rhizobium bacteria and then inoculated both with mycorrhizae.  Now it’s late April 2012, and it’s still alive and growing like crazy!

Here’s what I learned:

#1 Rye and Vetch Change Soil Drastically (PRO)

When I dug out bermuda grass (and a lot of trash) to make my veggie beds, the soil was dry, hard, and dusty.  I knew it would take a long time to reach the desired chocolate cake consistency – dark, moist, spongy, and smelling good and earthy.  With the rye and vetch cover crop, it’s almost there, and a huge difference from last summer!  The soil underneath the cover crop is very soft and spongy with beautiful aggregates.  This good structure will allow veggie roots to grow rapidly and air and water to percolate down into the root zone.

A great gardening goal is to always have something green and growing.  No bare soil!  Plants feed beneficial microbial soil life through root exudates.  As this cover crop was growing, it leaked a lot of sugary carbon compounds out of its roots to attract and feed microbes.  These bugs made the gums, glues, and gells that form soil into that chocolate cake consistency.  Bare soil has no living roots to maintain beneficial microbes at high populations through the winter.  Keeping soil life alive during the winter improves soil and ensures it’s ready to help veggie plants thrive in the spring.

#2 Plant-Available Nitrogen (PRO)

Nodules: Rhizobium bacteria fixing nitrogen on vetch roots. From http://ryansgarden.com

Instead of using synthetic nitrogen or expensive organic nitrogen inputs, why not grow vetch?  If inoculated with Rhizobium bacteria, the Rhizobium will fix nitrogen from the air and put it into nodules on vetch roots.  Isn’t that the coolest thing?  This handy cover crop reference says,

“Few legumes match hairy vetch for spring residue production or nitrogen contribution.  […] Hairy vetch delivers heavy contributions of mineralized N (readily available for the following cash crop).  It can provide sufficient N for many vegetable crops, partially replace N fertilizer for corn or cotton and increase cash crop efficiency for higher yield.”

That’s a whole lot of nitrogen!  And it comes at low expense with many other benefits.

#3 Weed Suppression and Free Straw Mulch (PRO)

Rye and vetch mulch drying down after cutting

No weeds here!  The cover crop’s outrageous growth in early spring smothers weeds by completely blocking sunlight.  I’m aiming for mostly no-till, so I’m cutting the rye and vetch off at its base.  This is generating a boatload of mulch!  Vetch mulch has a high nitrogen to carbon ratio, so it will decompose readily.  But rye straw at this late stage of growth (flowering seed head) has a lot of carbon, so it should last well into late summer.  This thick mulch will protect soil, keep soil temps cool in the summer so biology can thrive, hold in moisture, and prevent dirt splatter onto veggie plants.  And it’s free and organic!

#4 Beneficial Predators (PRO)

I’ve noticed a very big and diverse above-ground soil life community in the rye and vetch.  Loads of tiny mites, beetles, crickets, spiders, and ladybugs.  The diversity and populations are larger than I’ve ever seen in my garden.  The handy cover crop guide cited a study that showed a rye/hairy vetch mix sustained a population of aphid-eating predators that was six times that of unmowed volunteer weeds and 87 times that of mown grass and weeds.  I’ll take it!  Let’s get our predator populations really going and save ourselves loads of time this summer killing harmful bugs!

#5 Bad Timing for Early Veggies (CON)

Flowering cereal rye can be mow-killed.

Rye and vetch can be killed any time with herbicides, but organic gardeners must be patient.  Vetch can be killed organically when it flowers (late April/ early May in East Coast zone 7).  Cereal rye can be killed organically when it flowers around the same time.  (Flowering grain means the seed head is developing and the little stamens (anthers?) start to come out and drop pollen.)  Rye and vetch will die at this time by mowing or just knocking it down flat at its base.  No herbicides.

But you want to plant peas and lettuce and radishes in early March?  Whoops!  Not gonna happen unless you till in the cover crop or use herbicides, both of which I don’t want to do.  You can keep cutting it down at ground level, plant your peas, and then keep cutting the rye back, but rye REALLY wants to live at this stage and will stunt your early crops.  I tried it.  I did not try acetic acid sprays, which is another option.

This situation requires better planning in the fall.  I’ll need to designate beds for early spring veggies, and plant winter cover crops that will winter-kill (die on their own from hard freezes), such as oats and radishes.  But for later-planted summer crops like tomatoes and peppers, I’ll definitely plant rye and vetch again.

Seed Sources

If you don’t have a local source, search online for “rye and vetch seed for sale.”  High Mowing Seeds sells five pound batches for about $20, plenty for a 1,000 sq. ft. garden.  Think of all these benefits for such a low cost!  Thanks for reading!

Acids and Exudates: Plant Diversity Improves Soil

The more I learn about farming, the more I realize that plants are truly wondrous living things.  It’s easy to think plants are boring and passive.  After all, they just sit there.  But here’s some news!  Plants are powerful chemists and VERY active participators in their environment.  For our farm, we now see plant properties and behaviors as a tool for rejuvenating our dead soil.  This post explains what we’ve learned so far and how we plan to implement our new plant knowledge.

 Plants Leak Yummy Exudates

At the 2011 Acres USA conference, we learned a lot about what plants do below ground.  We learned that plants make a lot of sugars and other compounds from photosynthesis, and instead of using them all for energy, they leak a lot of them from their roots to attract and stimulate soil microbes.  These compounds are called “root exudates”.  

Plant root exudates. "Signaling molucules" that stimulate beneficial bacteria and fungi. From Marschner, 1995. http://edu.griggbrothers.com/TechnicalBulletins/TB2008b_printer.shtml

We learned even more about root exudates from Jill Clapperton.  She said that every plant variety leaks its own signature of chemicals in the form of amino acids, carbon, and organic acids to attract the beneficial soil microbes it needs to live and thrive.  She said that plants modify their environment and build their own microbial community in the soil.  Plants MODIFY their environment and build their own community?  This was news to us, and we thought it was really cool! 

She went on to say that plants leak a LOT of chemicals.  These chemical compounds are signs of welcome and warning.  Most of the compounds are welcome chemicals that attract a very beneficial and helpful bacteria and fungi community that like the plant and promote its growth.  Plants also leak warning compounds to keep themselves safe from soil herbivores and other threats. 

Exudates Can Improve Soil

Then Clapperton started talking about how farmers and gardeners can take advantage of plant properties to improve soil and grow food that’s very nutritious.  She encouraged the audience to fill the soil profile with different plants that have shallow, medium, and deep roots.  Filling the soil with many diverse plant roots will take advantage of the fact that all plants leak different compounds that will stimulate different segments of soil’s beneficial biology. 

Our soil has a long way to go before it is truly fertile with a fully restored biology.  We need a diverse soil biology community, so we were very interested in what she said about advantages of different plant categories:

  • Cowpeas (black-eyed peas), one of the best legumes for building soil.

    LEGUMES such as peas, beans, clover, and alfalfa leak exudates that attract both Rhizobium bacteria and mycorrhizae fungi.  Both of these are huge plant growth promoters.  Rhizobium fixes nitrogen from the air in return for sugary exudates.  Mycorrhizae are amazing symbiotic fungi that work wonders for the soil.  They go for maximum carbon exudates from the plant.  To get what they want, they boost the plant’s photosynthesis by conferring drought resistance and bringing phosphorus, copper, zinc, manganese and other ions and amino acids to the plant.  By making the plant healthier, they get even more carbonaceous exudates from their host.  Mycorrhizae turn a lot of it into glomalin, a significant carbon component in the soil that helps glue soil particles together and form wonderful aggregates that let more air and water percolate through the soil.  Legumes are clearly a win-win-win for soil.

    Sorghum, a warm season grass

  • CORN and WARM-SEASON GRASSES and Broadleaves such as SUNFLOWERS leak massive amounts of exudates.  They are trying to attract a large, diverse microbe community for protection and growth promotion, including lots of mycorrhizae (myco).  So this plant category can also stimulate lots of soil biology and sequester quite a bit of carbon via myco.
  • BRASSICAS such as mustards, radishes, broccoli, kale, etc. are different.  They do not associate with

    Mustard, a great brassica for improving soil.

    myco.  Instead, they leak some rather harsh acids.  They don’t need myco to go get soil minerals because they can use acids to get it for themselves.  Brassicas’ acid exudates can cleave off calcium that is tightly bound to phosphorus in the soil.  The brassica plant then soaks the phosphorus right up.  That’s why planting brassicas is a good method for “mineralizing” tightly bound phosphorus and making it available for the next plants that grow as the brassica decomposes.  Brassicas also stimulate the middle of the soil food web, arguably the most important part – the mites, earthworms, and other recyclers that prey on bacteria and fungi to keep them in a healthy balance.  Clapperton said she found through multiple studies that for some reason, brassicas make earthworms and other soil animals go really nuts in a good way.  So brassicas are key for mineralizing hard to get soil minerals and for stimulating the very important soil animals.

    Alfalfa

  • DEEP ROOTERS such as ALFALFA and SWEET CLOVER can bring up fertilizers from long ago that have leached deep into the soil profile.  The long roots also make channels for earthworms and other beneficial biology to travel.  The channels provide for better air and water percolation which fights compaction and improves soil structure.
  • POLLINATORS like PHACELIA and other FLOWERS have nice, fine roots with lots of fungi.  As pollinators, they can attract more above-ground diversity to our farm.

Our Plan

We probably won’t get livestock this year, so we’re going to take advantage of our prolonged delay to improve the soil by growing a big cover crop cocktail.  We’ve ordered the seed mix that includes several varieties from each category mentioned above. 

 

Phacelia tanacetifolia, a native pollinator that also helps rejuvenate soil. And it's pretty!

Our neighbor’s 20 acres has a rye and vetch cover crop growing like crazy right now.  We’ll mow when it flowers to kill it, then drill (plant) the cover crop seed.  Our own 20 acres are in perennial grasses (planted fall 2008).  We’ll lightly rotovate them to kill, then drill in the cover crop. 

We’re really excited to see how the cocktail grows.  With the big diversity of plants and flowers, I’m hoping it will be super pretty.  As late summer nears, we hope to see more wildlife and insects and good water retention.  And as all the different plants stimulate all parts of soil life, we should see our subsequent crops growing much better.  Thanks for reading!