Archive for the ‘microbes’ Category

Soil Quality Indicator: Do You Have Mophead Roots?

Check out this picture:

From November 2012 Acres USA article by Hugh Lovel.

From November 2012 Acres USA article by Hugh Lovel.

Have you ever noticed the degree of soil adhesion on your plant roots?  The roots on the right are what we want.  And I know for sure that our pasture roots aren’t there yet.  See the pic at the bottom of this recent post.  It resembles roots on the left. 

Mophead roots mean the plant is photosynthesizing very well and is healthy enough to donate a lot of sugary photosynthesis products to soil microbes via root exudation.  When these sugar goodies start seeping out of roots, soil microbes in the rhizosphere (root area) have a 5-star dinner and start multiplying like crazy.  They make the gums, glues and gels that cause soil adhesion and start delivering minerals and vitamins in plant-friendly form so the plant will get even healthier and make more sugary snacks.  Ain’t it neat?

The roots on the left show a plant that isn’t healthy enough to donate many photosynthesis products to soil microbes.  The plant is probably in survival mode.

Mophead roots are a sign of a fully functioning plant/soil ecosystem.  In our quest to increase our soil’s organic matter, mophead roots are the holy grail!  Those sugary snacks are carbon-containing molecules that get digested through the soil food chain and eventually get turned into stable organic matter.  And well-fed soil microbes will help plants make even more carbonaceous snacks, and in turn, more organic matter. 

 We have some grass that survived rotovating and is growing astoundingly well in our cover crop plots.  I’m going to check the roots this spring to see if they’ve reached mophead status.   Thanks for reading!

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!

Summer Cover Crop Cocktail – Six-Week Update in Pictures

We planted a warm-season cover crop cocktail on 40 acres during the weekend of May 18th.  See our seed chart and details here.  We’re hoping the cocktail will supply all the benefits of typical one- or two-variety cover crops (organic matter production, erosion prevention, nutrient availability) and greatly amplify all these benefits with diversity.  Cocktails planted on other farms have shown that all the plant varieties cooperate and thrive instead of compete.  Many believe this is caused by the plant varieties leaking their signature root exudates into the soil profile to stimulate their desired segment of beneficial soil biology.  With a field’s entire soil biology stimulated like never before, the whole soil/ biology/ plant ecosystem starts cranking!  It’s really neat stuff!  On our three-acre field, which has the best soil quality out of the 40 acres, we’re already seeing these very positive effects including drought resistance, very high quality plants, and low bug and disease pressure.

Let’s start with our neighbor’s east field.  This field was in roundup-ready soybeans for about a decade until fall 2010.  We planted a sorghum-sudan & cowpeas cover crop in spring 2011, rotovated that in with beneficial microbes, then planted a winter rye & vetch cover crop last fall.  We then successfully mow-killed the vetch and planted the summer crop cocktail this May.  Cocktail plant quality doesn’t look as great as our stupendous 3-acre field, but the cocktail is growing despite suffering in the eastern U.S. heat wave.  This field’s soil test results are good, not great.  It is short on calcium and micronutrients like zinc.

Summer cover crop cocktail six weeks after planting. Buckwheat and Dwarf Essex Rape are flowering.

The wide view pic above shows that buckwheat and dwarf essex rape are currently dominating.  These plants are the tallest and are blooming profusely with white and yellow flowers.  It would be ideal to mow these two before they set seed, but I don’t want to cut the other plants in the cocktail.  Mowing plants at flowering ensures most of the nutrients stay in the soil.  When plants make seed, the plant sucks nutrients and sugars from the soil to assist in seed production.  This is a tradeoff that goes along with a highly diverse (20 varieties) cocktail.  On the plus side, these two plants are giving us free seed that will germinate later.

Phacelia in foreground surrounded by brassicas and millets showing heat and drought stress. Neighbor’s east field.

The ferny-looking plant in the middle foreground is phacelia.  Its beautiful purple bloom should pop out any day now.  The brassicas and millets surrounding it are showing some stress from near 100-degree heat for several days and no rain for three weeks.

Our Best Field Shows Cocktail Benefits

Now let’s go to our 3-acre field.  I mentioned in the first paragraph that this is the best field out of the 40 acres.  Its soil test results are good, showing decent nutrients for our very sandy soil.  We took it out of roundup-ready soy production in fall 2008 and planted pasture grasses that failed to thrive for three years.  We rotovated the grass in fall 2011 while spraying beneficial microbes, then planted rye and vetch for the winter.  This spring we mow-killed the rye and vetch and planted the cocktail.  On top of this management, we spread horse manure compost (we go get free horse manure and compost it for about 9 months in static piles).

I’m not sure if the compost explains the health of this field or if it’s the combination of everything we’ve done.  But something is going on!  Some orchard grass survived our rotovating, and it looks night-and-day different from orchard grass in our existing pasture just 20 feet away.  The orchard grass in our pasture is lackluster and starting to go dormant in the drought.  The grass that survived rotovating in the 3-acre field is still dark, dark lush blue-green with no signs of going dormant yet.  Imagine if we had all our pastures filled with grass like this!  It’s some good quality grass for our future livestock.

Healthy sorghum in cover crop cocktail.

Take this above pic of sorghum (looks like corn) surrounded by the other cocktail plants.  The sorghum looks great despite high heat and drought and no nitrogen fertilizer.  This makes me super happy because the soil is clearly providing nitrogen to this nitrogen-hogger of a plant.  Only soil that has reached a decent level of health with a nicely functioning biology community can do this.  The brassicas around this sorghum plant have very large waxy leaves with very little insect pressure.  I can’t get brassicas in my veggie garden to look this good.  Something great is going on in this field!

Sunn hemp and Camelina surrounded by brassicas in cover crop cocktail.

Here’s a pic of sunn hemp and camelina in the center with brassicas all around.  Sunn hemp (left) and camelina (right) look similar at this point, but that will change soon.  Sunn hemp can get giant-tall.  Camelina is an oil seed brassica like dwarf essex rape.  It’s starting to flower, so it will probably stay short.

We’re excited to see what sunn hemp can do in our fields.  It’s a legume, and we inoculated the seed with its preferred Rhizobium bacteria.  This bacteria works with the plant to create huge golf-ball sized nodules on sunn hemp roots.  These Rhizobium nodules fix nitrogen from the air in return for sugary root exudates from the plant.  When sunn hemp dies, the nitrogen will get released into to soil, hopefully just in time for our next winter cover crop’s grasses (oats and rye) to pick it up and use.  This is how cover crops can be a giant nutrient recycling machine that keeps high quantities of necessary nutrients available rather than locked up in the soil.  On top of the nitrogen benefit, sunn hemp can grow up to 10 feet tall!  That’s a lot of nice biomass that holds carbon, nutrients and vitamins.  It will make high quality mulch for the soil after we mow it down.

Big mustard plant in summer cover crop cocktail

Here’s an extra large mustard plant surrounded by millets and blooming buckwheat.

Peredovic sunflower six weeks after planting in cover crop cocktail.

Here’s a sunflower popping up with cowpeas, millets, brassicas and some weeds.  I’m not gonna lie!

Cosmos plant in cover crop cocktail.

I’m very excited to see this cosmos and can’t wait to see its hot pink flowers!  I haven’t seen the other flowers/herbs we planted such as dill, coriander, alyssum.

Big turnip growing well in cover crop cocktail.

To give you an idea of how well the brassicas are growing in this 3-acre field, check out this turnip.  The top of the bulb is already 3 inches wide!  Brassicas stimulate earthworms and other important soil animals and can suck up a lot of nitrogen and phosphorus that was otherwise stuck and unavailable in the soil, so we’re very, very happy the brassicas are growing so well.

Cocktail Failures

Time to take it down a notch and talk about what didn’t work.

Our pasture seeding is a failure.  We planted the same 70 pounds of seed per acre in our existing pastures that we planted in all the other fields, but so far we have just a few wimpy soybeans rising above the grass.  We didn’t expect the cocktail to grow fabulously in our pastures, but we thought many more plants would grow.  Seems our big mistake was not waiting until the pasture grass went dormant.  The cool season grasses were way too competitive with the new seeds in May and June.  We’ll wait to see if more cocktail plants start growing as the cool-season pasture grass starts to poop out in July and August.

Wimpy soybeans coming up in pasture. Pasture seeding didn’t work with cool season grass in May.

Another failure is our neighbor’s west field.  I wrote at the bottom of this post how mowing the vetch twice in this field allowed a lot of sunlight to get through and prompt volunteer annual ryegrass to sprout and grow like crazy.  Well, the annual ryegrass is strongly competitive and has prevented the cocktail from growing.  I should have made sure the annual ryegrass was dead before we planted the cocktail.  We sure are learning our share of expensive lessons!

What’s Next

We’ll let the cocktail grow for another six or seven weeks, then mow it to kill in mid to late August.  Then we’ll come in and no-till drill (plant) a cocktail for winter.  Many of the summer plants will survive mowing and won’t die until the first hard frost, which happens around Halloween here.  We have some experience with this with sorghum-sudan going into rye and vetch.  We’ll see how it turns out transitioning with cocktails.

We hope come mow-time in August that most of the plants are flowering or starting to make seed.  Plants at this stage are easy to mow-kill.  In the meantime, we’re very happy we experimented and planted this cocktail.  Each plant variety is doing its own little thing in the fields such as stimulating soil biology, manufacturing carbon for the soil, and harvesting minerals that will be very available for subsequent plants to use and thrive.  It’s way cool to use plants that will go to work for us and contribute all these benefits for improved soil health!

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!

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