Archive for the ‘rotovator’ Category

Save the Microarthropods! Rethinking Tillage and Rotovating

We’ve gone from tillage-happy to tillage-doubtful.  We learned some things about tillage at the December 2011 Acres USA conference that really resonated with us, so we’re reconsidering our plowing down cover crop strategy in order to nurture a key part of the soil food web…

Rotovating in late August 2011

Up to now, our strategy for improving our sandy soil’s fertility involved growing massive cover crops to maturity and then plowing them down every spring and fall.  The “plowing down” involved using our rotovator (a very wide garden tiller) to incorporate most of the plant tissue into the topsoil so it could stimulate soil biology and eventually break down into organic matter.  At the Acres conference, we got confirmation from several speakers that this was the best method for improving soil’s biological fertility, especially if the plants are mature and lignified (more brown than green).  It felt great to hear this because it fit exactly with our plan!  Then we heard Jill Clapperton speak.  She was the rhizosphere ecologist for Canada’s agriculture department, and her research really compelled us to reconsider tilling so often.  Here’s why:

Lots of Tillage Hurts the Soil Animals in Middle of Food Web

Soil Food Web

The bottom of a very simplified version of the soil food web starts with bacteria and fungi, which are the primary digesters.  The middle group is the small animals, and they eat everything!  They prey on each other, bacteria and fungi, and plant residue.  This group consists of microarthropods (mites), earthworms, nematodes, enchytraeids, and some protozoa.  The top of the simplified food web is the larger animals that live on the soil surface like springtails, beetles, and even mammals like field mice.

Clapperton talked about long-term research results that showed some of the small animals in the middle of the food web disappearing after five years of tillage.  She said most of the small animals, especially the microarthropods, make their homes in the top few inches of the soil, and when tillage repeatedly destroys their infrastructure, the animals just leave.  The microarthropods cannot live in such an unstable environment.

Plants pick up and assimilate nutrients that have gone through soil’s biological system much better than nutrients from fertilizer.  For this reason, it behooves us as farmers with the goal of growing top quality grass to nurture the soil’s biology as much as we can.  We’d love to have the microarthropods on our farm just because they’re pretty amazing animals, but more than that, they are a very essential part of a vibrant soil food web.

Microarthropods are Voracious Predators

Macromite's Blog selection of soil mites, springtails, and Parajapyx. http://macromite.wordpress.com/2009/04/29/a-menagerie-of-microarthropods/

The animals in the middle of the food web are soil’s predators and recyclers.  This video shows two soil mites battling over a juicy springtail.  If we saw large, familiar animals trying to rip apart another animal like this on a regular basis, we’d probably have a whole different view of nature!  But violent predation like this happens all the time in the soil, and the soil’s health, and therefore the nutritious quality of our food, depends on it.  Here’s how:

The microarthropods chew up bacteria and fungi, poop them out, and regenerate the whole food web cycle in a very positive way around plant roots.  Without the good, natural predation check, the bacteria and fungi proliferate too much and start competing with plants for nutrients that plants need to grow and thrive.  Soil bacteria and fungi will beat out plants every time for nutrients if they’re allowed to do so.  Therefore, predators like microarthropods are essential for healthy, vibrant plants.

Microarthropods Stimulate the Soil Food Web

The microarthropods also help out bacterial and fungi.  They eat everything, including each other and larger pieces of plant residue.  Everything they eat is pooped out in new, much smaller particle sizes that are now accessible to bacteria and fungi for food.  This stimulates the bacteria and fungi to multiply at a good rate, in turn feeding the whole system.

Tiny Oribatid mite: Synchthonius crenulatus (Jacot) on a Times-Roman 12 pt Period. At http://macromite.wordpress.com/2009/07/01/full-stop-on-canada-day/

So, the middle of the food web is essential to healthy soil and therefore, high quality grass.  If repeated tillage makes them go away, we’re going to stop.

Our New Plan

Instead of rotovating our cover crops into the soil every spring and fall, we’re going to instead mow at the right time to kill them.  Clapperton advocates mowing because the clippings act as a good armor for the soil, and they insulate the soil from temperature extremes.  This helps the soil food web stay active during the hottest, driest times of the year.  She also said plant roots are soil’s most available form of organic matter.  Roots leak carbon and nitrogen compounds constantly to stimulate beneficial bacteria and fungi.  When the plant dies, the roots decompose into organic matter, and the tunnels left behind are great for air/water infiltration and for providing movement channels for earthworms and other animals.  Another disadvantage of tillage is that it collapses a lot of these tunnels.

We’re not going to sell our rotovator.  We’ll use it this spring to rough up our 20 acres of perennial pasture so we can give our new cover crop cocktail a good chance to grow.  We’ll rotovate very lightly and probably leave a lot of the grass standing.  We’ll then plant successions of cover crops, and then plant our final perennial pasture mix for grazing.  We might not ever need to rotovate our fields again, unless we want to kill the perennials again to do some crop rotation, or we detect soil compaction problems (unlikely in our very sandy soil, with the help of cover crops).

We hope that our new plan will help our soil thrive.  Giving up repeated tillage will hopefully give our farm a very healthy, complete soil ecology that includes the very necessary predators and recyclers and will also help maintain good soil structure with intact earthworm channels.

Most of the info in this post came from Jill Clapperton’s two presentations at Acres.  Audios of her presentations are available here.

More Lessons Learned with Rotovating Sorghum Sudangrass (and a Bright Side)

Our rotovator fought the cover crop, and the cover crop won!  We grew sorghum sudan this summer on our neighbor’s fields as a green manure crop.  We rotovated it in early August to incorporate most of the crop into the topsoil.  We wanted the crop to feed the soil life and turn into organic matter.  Our goal is to move this dusty, sandy soil toward crumbly, black, “chocolate cake” soil that makes plants and animals thrive.

Rotovator Failed to Kill Sorghum Sudan

We also wanted the rotovator to kill the crop so we could plant the next cover crop of cereal rye and vetch for the winter.  We had very limited success here and still can’t tell what we did wrong with the rotovator!

Frosted sorghum sudangrass, 3 feet tall after failed rotovating

You can see the sorghum sudan in this picture taken in mid-November, about two weeks after a killing frost.  The sorghum sudan completely re-grew from the roots after rotovating and is finally starting to die from a cold snap.  Finally!

Rotovating is supposed to easily kill a crop, so we obviously did something wrong.  Perhaps the blades were not set deeply enough.  Perhaps we went too fast.  These scenarios are both perplexing though, because on the last field we set the blades to the deepest possible level, and the crop still grew back just as thick.  And the speed – we were going so slowly, I’m embarrassed to admit how long it took us to cover 20 acres.  Let’s just say days, and I won’t say how many!

I have heard that sorghum sudan easily grows back from the roots, such as after animals eat it down to the ground.  So maybe we just have to take extra steps when rotovating this crop and disturb the roots more?  We rotovated two acres of old grass pasture, and the grass died completely, no problems there.

Fluffy Soil Not Good for Planting

Another problem we need to figure out is extra fluffy soil.  The soil that the rotovator left behind was fluffed up, so much so that our boots would sink down about an inch when we stepped on it.  Turns out this does

our 7-foot rotovator

not bode well for the next crop.  We rented our county’s seed drill to plant the winter cover crop of rye and vetch about three weeks after rotovating, and it germinated very poorly.  I asked our Extension Agent for his opinion, and he said seed with poor soil contact has trouble germinating, and the 10 inches of rain from Tropical Storm Lee that we got right after planting likely made things worse.

So how do we make a good strong seedbed after rotovating?  We had the rotovator’s backboard down most of the way; maybe it should be down all the way.  Also, we can use time.  All the extra air eventually leaves the soil.  The soil needs at least 4 weeks to fully digest plowed down vegetation anyway (especially with no spraying of microbes), so we’ll just wait longer.  Our Extension Agent said our boots shouldn’t sink more than ¼ inch.  Any more than that, and the soil is probably too fluffy for drilling seed.

So far, I’m far from in love with rotovating!  It takes forever, and its performance feels like false advertising, far from the praise rotovators receive for their ability to kill plants, incorporate them, and make a nice seedbed all in one pass.  Surely it’s not too good to be true!  Hopefully it’s something we’re just missing.

Bright Side

Okay, enough of the whining!  There is a bright side.  Sorghum sudan is unrivaled among cover crops it its ability to produce biomass.  It gave us three good growths on zero added nitrogen fertilizer, and the root system below ground probably came close to mirroring the plant above ground.  We mowed twice and rotovated once, so that’s a good sloughing off of roots times three.  As the roots die and break down and form organic matter, the empty spaces will make great tunnels for earthworms.

Sorghum sudan’s other significant contribution is its amazing allelopathic (natural weed killer) effect!  During the 2010 summer season, these soybean fields were inundated with roundup resistant weeds like marestail and water hemp.  I can’t find nary a one now!  When we converted our own fields from GMO soybeans to grass pastures, we had to beat back marestail for 2 years by mowing.  Sorghum sudan is extremely helpful in this area!

Moving On…

We mowed the sorghum sudan for the last time in mid-November, as it was dying from frost.  The clippings made a good mulch for the soil.  The rye and vetch cover crop is growing well here and there, and cool-season weeds, Italian ryegrass volunteers (from previous winter cover crops) and the mulch do a good enough job of covering the soil in the other spots.  For this reason, we’re not going to replant the rye and vetch.  We plan to mow-kill the winter covers in the spring and then plant another summer cover crop like buckwheat.

Learning How to Rotovate a Green Manure Cover Crop

In mid-August we rotovated (shallow-tilled) our sorghum sudangrass and cowpea cover crop.  This post will describe the learning curve we encountered with our first time rotovating and how we got it to work.

Good mix of brown and green plant material

We planted this cover crop at the end of April, let it grow to about 5 feet tall, and mowed it in July.  Our bush hog made a lot of nice mulch.  After a week or so, the sorghum sudan and cowpeas came charging back mean and green and grew about 18 inches.  This is exactly what we wanted.  We wanted to rotovate green plant material “green manure” to feed and jumpstart soil life, and brown mulch material to breakdown and transform into organic matter.  These fields (our neighbor’s) were previously planted in no-till roundup-ready soybeans for at least a decade.  Organic matter is very low, below 2%.  Our goal is to stimulate all the soil critters to grow and multiply and bring life back to the fields.

our 7-foot rotovator

Rotovators are tillage tools, like a very wide garden tiller.  Our rotovator is 7 feet wide.  It has no wheels.  Instead, it skids along the ground like a sleigh, and the tractor’s 3-point hitch keeps it level.  We rotovated 25 acres of sorghum sudan and cowpeas (our neighbor’s fields) and two acres of our own grass fields.  In addition to the rotovator, our tractor was carrying a homemade spray tank on the front.  The spray tank is described here, and the spray mix (beneficial soil microbes and other goodies) is described here.

Why Rotovate?

We want to decrease the time it takes for the fields to get healthy.  Our own fields, which were previously under the same soybean farmer, have been in pasture grass for the past 3 years.  We’ve been mowing 2 or 3 times per year, fertilizing, and applying compost.  Unfortunately, we’ve seen very little improvement in the grass.   After studying biological farming techniques, we’re convinced the soil needs some disturbance to break up the sandy, crusty topsoil and to get a good dose of plant material and biology into the root zone.

Incorporating a green manure crop is essentially chopping plants and feeding them to the soil.  Five percent of a plant’s makeup comes from the soil (ash/minerals), and the remaining 95% comes “free” from photosynthesis of sunlight, water and air.  Incorporating the minerals (now in plant form) and all the free stuff like carbon, vitamins, and plant metabolites, provides a huge benefit to the soil in terms of improved soil structure and energized soil life.  We’re aiming for “chocolate cake” soil:  very dark, loose, and crumbly with high organic matter and a very healthy soil ecology.

Starting Out

Our goal was to rotovate as fast as possible (to decrease time in the tractor) and still be satisfied with the results.  In terms of results, we wanted to see most of the mulch incorporated into the top 4 inches of soil with a good mulch cover left on the surface for protection.  We also wanted to see a relatively smooth seedbed, but not so smooth that our sandy soil was pulverized.

We quickly discovered that getting our desired results would take a lot of trial and error!  On top of taking a large amount of time, rotovating includes many variables:  tractor speed, rpm, soil moisture, rotovator blade depth, vegetation content, row coverage (overlapping), and the position of the rotovator’s back gate.

Rotovating too slowly- powdery soil with little surface mulch

Lesson #1:  Don’t go too slowly.  On the first day, we started rotovating in our tractor’s 2nd lowest gear at about 1900 rpm.  (The rotovator manual said 1900 was the max).  This is moving VERY slowly, about 2 mph.  2nd gear cut the plants off at ground level but left them all on the soil surface.  The blades seemed to be bouncing a little instead of digging down.  Then we tried 1st gear at 1900 rpm.  Going slower allowed the blades to get into the soil, but the rotovator now chopped the soil way too much and turned it into powder.  All of the vegetation was incorporated with hardly any protective mulch on top.  It was getting dark, and we hadn’t even finished two acres.  We decided to sleep on it and try again tomorrow.  That night, it started raining heavily.  I had nightmares recalling the old 1930s TVA movie clips showing drastic soil erosion!  I didn’t feel good about the soil turning to powder.  It felt like a giant step back, and I was worried.

Pile made by rotovator catching mulch from previous row and dragging it.

The next morning, we walked out to look at the fields.  No erosion at all, everything was fine.  Except now in the morning light, we could see all the big piles of soil and mulch the rotovator created.  One side of the rotovator kept catching on the mulch in the previous row and dragging it until it balled up big enough to discharge out the side.  It was discouraging because we didn’t want to bring our tractor back over those nice and fluffy rows to smooth out the piles.  The tractor is heavy and would compact the soil and remove all the air that microbes need when they’re working.  Looked like we’d be pitch forking them by hand!  (We did.)

Lesson #2:  Don’t rotovate bone-dry soil.  We waited a few days for the rains to stop and the soil to dry out.  We knew 1st gear was bad, so we tried 2nd gear again at a little lower rpm, 1800, and we also set the blade depth deeper.  Voila!  It worked!  Most of the mulch was getting incorporated with some left on top.  But the major lesson here was soil moisture.  After the rain, the moisture level was now just right.  The soil’s aggregates stayed together in nice, small clumps.  It was too dry on the first day, and that’s why it got pulverized so easily.

Uneven seedbed from rotovating in 3rd gear with gate up

Lesson #3:  Leave the back gate down if you need a smooth seedbed.  We were still making the big piles though, and we couldn’t figure it out.  We decided to go faster, in 3rd gear, and lift the rotovator’s back gate up so all the mulch could leave without balling up.  This just helped make the piles a little smaller.  Also, keeping the back gate up left the soil surface very uneven.  That was another concern because we didn’t know how the drill (planter) would perform in a seedbed that bumpy.  We put the gate back down.

Lesson #4:  Don’t overlap rows.  It wasn’t too much longer when we discovered what was making the big piles.  I was bringing an iced tea out to my hubby in the tractor.  When he saw me to his far left, he turned his head and waved.  I saw the tractor and rotovator steer to the left far into the previously rotovated row, and a giant pile came out the side!  From then on, we concentrated hard on keeping the rotovator squarely on unrotovated ground.  This was hard to do continuously, but it worked!  We ended up leaving very narrow strips of the cover crop standing just so we’d avoid the piles.  This didn’t look very good, but we’re fine with it because the sorghum sudangrass and cowpeas will both die at frost.

Just right - moist soil, most of plant incorporated with plenty of protective mulch left on top

Lesson #5:  Do lots of test runs on the day you’re rotovating.  We ended up going back down to 2nd gear at 1800 rpm for most of the job.  The cover crop was very lush and thick in some places, and we needed a slower speed for most of it to get incorporated.  However, when we rotovated our 2 acres of pasture grass, we could go back up to 3rd gear.  The density of the vegetation makes a difference.

With all the variables involved, it’s key to test before you start to find the happy medium for that day.  Make sure your soil has some moisture (but not anywhere near wet) and start testing to see what speed and rpm gets most of the plant material below the surface and still leaves a protective mulch cover on top.   And if you start creating big piles, stop overlapping the rows!

Hurricane Irene Side Note:  Irene came two weeks later with 85 mph winds and 10 inches of rain.  The next morning, there was surprisingly little water standing and no sign of erosion.  The large quantity of mulch, both below and above the surface, protected the soil well.

Building a Front-Mounted Boom Sprayer for Your Tractor

This post describes how we built our front mounted boom sprayer and how we adapted to get the job done after making some big mistakes.

Tractor with 3-point hitch rotovator and front-mounted spray tank on forklift attachment

We equipped our tractor with a front mounted boom sprayer to help get biology into our worn-out soil.  We wanted to apply beneficial microbes to our cover crop just before we rotovated (shallow-tilled) it back into the soil.  A tractor with equipment mounted in both the front and back accomplishes two operations in one.  We can spray in the front and rotovate in back (reminds me of the famous mullet hairstyle joke!), all in one pass across the fields.  This saves lots of time and soil compaction.

We were initially willing to purchase a front mounted boom sprayer, but we had an extra hard time finding one!  We looked at the specialized sprayers for orchards, but they were very expensive, and most of the tank capacities were less than 50 gallons.   We also saw front mounted sprayers for huge tractors, but there was no way our tractor could handle a 500-gallon tank.  We were hoping for a tank capacity around 100 gallons.   We saw plenty of 3 point hitch (for the back of the tractor) boom sprayers, but they were expensive too, and we’d end up taking off the 3 point attachments anyway.   

So we had an idea:  our tractor already has a fork lift attachment, so why not strap the tank onto that?  We bought parts – 100-gallon tank ($250), agricultural 1 gallon per minute spray pump ($80), and a boom with nozzles ($180).  We already had other materials:  electrical wire to run the pump switch into the tractor’s cigarette lighter, tie-down straps, flexible water tubing to connect the tank to the boom, etc.  This worked like a champ with water, and we were excited to get going.

Front-mounted spray tank - first design with spray pump connected to boom

The problem came with molasses.  We wanted to add some kind of sugar with the microbes to the tank.  Sugar wakes up the microbes and gets them going.  Molasses is highly recommended because it’s sweet and contains minerals.  What we would give to go back in time and pay more for liquid molasses instead of dry molasses!  Dry molasses is much cheaper ($18 per 50 pound bag), and it’s easy to get at farming supply stores.  It’s an animal feed, and this animal liked it!  It smelled really good and tasted like raisin bran.  We wanted to spray at least 5 pounds of sugar per acre, and the bag said dry molasses had 38% sugar.  We did a test rotovating run and determined each tank would cover just under 2 acres, so we added half a bag (25 pounds) to the tank with the recommended rate of microbes and filled up the tank with water. 

Well, the sprayer nozzles clogged within 5 minutes!  In our studying of the dry molasses bag to find the sugar content, we somehow missed the words in big font that said “22% FIBER”.  Once it was soaked in water, the residue was like oatmeal.  The nozzles couldn’t handle it, and the spray pump also clogged after we took the nozzles off and tried to just pump the mix out through the lines.

We were frustrated!  We were in a good weather window, and lots of rain was predicted to start in the next few days.  We started steeping the molasses in 5 gallon buckets and filtering it through a kitchen colander.  Took forever! 

Second design- note new flexible piping, valve, and pvc on top of tank

We couldn’t take the spray pump completely apart to clean it, so we opted for another route.  We weighed down a sump pump at the bottom of the tank and connected it to a ¾ inch diameter pvc pipe with holes drilled in it.  Since the sump pump put out way more than a gallon per minute, we put a valve in between the pump and the pvc pipe and partially closed it.  More liquid was coming out of the holes closest to the pump, so we wrapped tape around the pvc to partially cover those holes.  The liquid was now coming out pretty evenly along the whole length of the pipe.

Out in the field, the streams coming out of the pvc pipe worked just fine.  Not every leaf got coated, but since microbes multiply, this is probably not a big deal.   

In summary, the molasses fiber mistake cost us about $260.  We can use the boom, but the spray pump is probably a goner.  We will probably get another spray pump and hook it up to the boom for future use, such as spraying foliar fertilizers where we want a fine spray.  But for getting microbes and sugar into the soil, the cheap sump pump and pvc pipe was good enough.  We intend to keep learning – we imagine we need some sort of filter and agitator inside the pump, and we probably need different nozzles.  Unfortunately, we again learned the lesson to not trust the “agricultural” label, such as agricultural nozzles.  These are used to mainly spray pesticides and herbicides (clear liquids), and we’re not in that line of business, so we need completely different components. 

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