Sunday, February 26, 2012

Building soil tilth

This post shows the process I used to convert an area of our suburban backyard, in Northeast Boulder from a grassy and weed overrun horseshoe pit to a productive vegetable garden. This garden bed, that I call the horseshoe garden, is roughly 500 square feet, running West to East and receives full sun. I grow organically and for me that means no chemical fertilizers or pesticides and mostly open pollinating seeds. I used and continue to use cover crops, green manure, smother crops, trap crops, compost, compost tea, wood chip mulch to build the clay dominated soil, attract pollinators, and help suppress weeds. While there are a variety of annual weeds in this bed, the problem weeds as I see it are the bindweed and Canadian thistle. Otherwise I manage the weeds with the traditional and grub hoes, shovels, weed eater, rear tine tiller, and by hand.
The process started in mid 2009 and the contents of this post run through early 2012.
Winter 2008
The first step was to remove the horseshoe pits and till the sod. I did this in July 2009 after being frustrated with the weedy lawn for the beginning half of the summer. I read that buckwheat could be used as a smoother crop "for even thistle". It is supposed to grow fast enough to "shade out" weeds and keep them in the dark. I used 2 pounds of seed. Buckwheat grows very fast. The below picture was taken about 10 days after planting and lightly raking in. I watered the entire bed with the in ground sprinklers, I installed longer risers on the sprinklers that I smashed with the tiller, front of the garden on the right side of the picture. You will notice that several of the sprinklers get raised in subsequent pictures, for the same reason. Since the plan is to make this a garden I want to eventually install a drip system, so I wasn't too upset when I broke the sprinklers.
July 24, 2009
This next picture is about a month later.
August 20, 2009
Buckwheat flowers fast! Lots of pollinators in the morning hours about 9 till noon. There are a couple of honey bee hives in our subdivision, and there was at least a honey bee per square foot during the morning hours and many other types of bees, wasps, flies, and misc bugs. I'll do a full write-up about the different "bugs" I see in the garden.
Seeds form shortly after flowering and to reduce the self sowing, get access for the back fence, and get ready for the next phase. The buckwheat was cut with a weed eater and tilled in. I should note that there was still bindweed and thistles present when I tilled. I hand pulled both while the buckwheat was growing, but didn't want to trample the buckwheat so my efforts were mostly on the edges where I could reach.
August 23, 2009
About a week later after the fence went up, I hand broadcasted 2 lbs of winter rye and a pound of hairy vetch, I used an inoculant for the vetch. Hairy vetch is a legume and is supposed to fix nitrogen better if an inoculant is used when planting, unless a similar crop has been grown in the ground in recent years. The inoculant is a mix of bacteria that works in a symbiotic relationship with the host plant, forming nodules on the roots. The bacteria is what actually fixes nitrogen from the atmosphere, the bacteria gets fed proteins by the host plant's roots in exchange for the nitrogen.  To accomplish this I first wet the vetch seed in a bucket with just enough water to wet the seed and mixed in the powdered inoculant by sloshing it around with my hand, I did this just prior to hand broadcasting. Then over the top of both seeds I threw on a cubic yard of compost from the garbage company's recycling program. A cubic yard is about a level pickup truck for my Ranger and cost $24. I had to wheelbarrow it in from the front yard and I was able to throw it on pretty evenly from the grass so I didn't bother raking it afterwards, but I did water it down. Our summers days are usually in the 90's F and with this area getting full sun it tends to heat and dry fast, so I watered daily with the sprinklers for 5 minutes in the evening.
August 29, 2009
Like the buckwheat, the winter rye is quick to germinate and a vigorous grower. The hairy vetch is slower to germinate and grow, but still got going fast. The goal is to get them both planted with enough time to build roots and enough top growth to survive the winter. Both plants are very hardy once established before freezing weather after which time they go dormant until warmer temperatures the following spring. Winter rye can grow at much lower temperatures than many other grasses and I believe would have been okay to plant 4-5 weeks later, my reason for selecting it was based on the fact that it grow extensive roots which help break up compacted soil and lots of top growth to add carbon matter to the garden. Hairy vetch is a thin vine type plant and uses the rye as a nurse crop. The vetch twists around the tall rye growing up versus just forming a twisted mat if grown alone.
 Sept. 6, 2009
You can see a big fat thistle to the left of center in the above picture. There was also plenty of bindweed that grew back. In hindsight, it would have been better to wait a couple of weeks before planting the rye / vetch and rototill again to knock down the weeds a second time.
Sept. 13, 2009
A benefit of winter rye is that it stays green much later in the fall / winter and greens back up in the spring sooner than lawn. I have read that rye can be hard to kill and become weedy if let go to seed. My reasoning was that my area was so small I could easily manage it.
 Oct. 3, 2009
You can see that the winter / vetch filled in fast and forms a good ground cover. They are about 5 inches tall and stayed this height through winter.
May 15, 2010
Our spring planting, last frost date, can vary and the safe time to plant seedlings is Memorial day. You can see some matting of the rye in the background this was from a heavy snow. In the foreground I have started cutting down the rye with my weed eater. 
What I read about rye is that its roots put out chemicals into the soil that can hinder growth of small seeds and young plants. I would guess that's the purpose of the chemical, to limit competition for the plant. It takes a couple of weeks for the soil / soil bacteria to break-down or otherwise reduce the effects of rye's chemicals and I wanted to get tomatoes into the garden by June.
May 15, 2010
The above is a view from the East end of the bed, from behind some lilac flowers (for effect) after cutting down most of the winter rye / hairy vetch. I left a small patch, about 2 ft x 5 ft, in the background of the above picture. I wanted to harvest some rye seeds for future plantings.
June 5, 2010
Here is the rye/vetch a few weeks later. In the rest of the bed I raked away the straw and rototilled in the stubble. Then redistributed the straw as mulch.
June 5, 2010

Here's a view from within the bed, the purple is hairy vetch flowers. There is also bindweed crawling up the rye. I did my best to hand weed the bindweed while this grew.
June 5, 2010
The bumble bees really liked the hairy vetch flowers.
May 29, 2010
Cosmo lives down our street and drinks out of our "beebath"
July 6, 2010
The Rye seeds are starting to plump. I hand picked these about a week after this picture was taken. At that point the seed head's were mostly bent over due to their weight and drying out of the rye stalks.You can make out the tomato plants to the right of the rye, still tiny.
The rye straw mulch was no where enough to shade the ground around the tomatoes and eggplants so I brought in a cubic yard of wood chips (no charge).
Oct. 30, 2010
Here's the tomato plants after a couple of hard freezes. The picture is bad and I wish I had one from a couple of weeks earlier. The harvest was good. See below.
variety of tomatoes (and squash from another bed)
Before the freeze, keeping with the same theme, I planted two areas of this bed, one where the rye/vetch grew and the other on the far right (East) with alternating rows of crimson clover and fava beans. Both of these plants are legumes and good plants to be used as winter cover, growing in the fall then going dormant till warmer spring temperatures. They both got established well, the clover forming a low mat and the fava beans growing 3-4 inches tall. While the crimson clover survived the winter very well the fava did not. Below next to the potato trench you can see the still dormant crimson clover. Since potatoes are in the same family as tomato and eggplant, the trench for the potatoes is to the right of where those plants grew in the previous season. This crop rotation should help break plant disease cycles. I plant to wait 3 years before planting a like crop into the same area.
March 19, 2011
May 22, 2011
Yukon Gold potatoes are starting to show they' were planted about a month earlier. To the right the crimson clover, some rye and hard to see hairy vetch are growing.
May 22, 2011
Same cover crops as above. The wall of water's on the left have peas, the one on the right has a dahlia (tuber). To the far right are rows of radish, turnip, beets, and arugula.

May 22, 2011
The bumble bees are back. Honey bees also liked the crimson clover but either their populations were low at this time of the year or they had more favorable nectar / pollen sources. Both of these cover crop areas were turned under by simply rototilling.

July 8, 2011
From left to right in the above picture are the Yukon Gold Potatoes, a row of amaranth, butternut squash, and sunflowers. all the way to the right is lawn / crabgrass growing back, its hard to get the rear tinned rototiller there.
August 6, 2011
Things are growing nicely. 
 Sept. 30, 2011
I'll stay on topic of cover crops and soil building. Most of the crops in the garden were planted in rows. I stopped the rows with about 2 feet to walk behind everything. In August I ran the tiller turning my walking path and planted some old radish seeds that I saved, figuring that they would get going and be frost killed in the fall (October). I also had a small amount of several of the cover crop seeds left. I used these in the center area where the beets&... were grown to have some winter cover and early spring growth.
July 10, 2010
Oct. 1, 2011
Right in the center there is a beet (beetroot) I left it in the ground so that I can harvest seeds.Beets are biannual producing seeds in their second year. All around the beets from the zinnias to the kohlrabi I hand turned the soil with a spade (back access is blocked with radish cover crop) and planted my remaining winter cover crops. There was about an inch of wood chips, now two seasons old, on the surface which I just turn in when digging.
 Jan. 22, 2012
I answered a craigslist ad from a tree company working in the area who gave me a load of fresh wood chips from my neighborhood. They dumped them in the front yard so I wheelbarrowed them into the back. Its about 2.5 cubic yards. The pile steamed for about a week as fungi and bacteria did what they could even with temps freezing every night. It snowed a couple of inches but the top of the pile just kept steaming.
 Feb. 26, 2012
Even though we've had a very snowy month so far (2 inches from the record and a few days to go), since this area gets lots of sun I will occasionally shovel some snow from the shady areas onto the cover crops to keep them hydrated.
So stay tuned. I plan to layer newspaper on the ground on unplanted areas and cover liberally with wood chips, lasagne garden style, to block weeds, then dig through to plant this spring.

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