Sunday, April 17, 2011

Straw bales and potato cages

Straw bales with soil topping and drip irrigation system.  We eat the dandelions, so I don't count them as weeds... ;)
* We linked this post at Monday Mania at The Healthy Home Economist and Real Food Wednesday at Kelly the Kitchen Kop *

My straw bale experiments are finally yielding some results, so I thought I'd pass on what I've observed so far, and give a little update on the process while I'm at it.

I ended up installing a drip sprinkler system to keep the bales watered, but we have actually had enough rain this spring that I only turned it on three or four times.  That means my bales didn't get watered every day, but averaged 3-4 waterings a week.  There were also a couple of periods in there where they got pretty dry, so I'd say this is a pretty "realistic" experiment in gardening for busy people!

The results are basically in for the different fertilizer combinations I was able to try:
  • Blood Meal: Bales reached temperatures of 100-110 degrees at peak, composted reasonably well.  There was no noticeable smell, and the fertilizer watered into the bales without much trouble.
  • Alfalfa Meal: The composting results seem to be comparable to the blood meal, at about half the cost.  One issue I had with the alfalfa meal is that it doesn't water into the bales well.  I addressed this by slashing the tops of my bales with a utility knife to make a layer of loose straw about 2 inches deep, then mixed the alfalfa meal in with that.  After doing that, the composting really picked up, so I recommend the practice.
  • Cottonseed meal: This initially worked quite well, but it seems to have cooled off too quickly.  I suspect that there was dust that kicked the composting into high gear, and when the dust was expended the much slower meal dominated the process.  I think the cottonseed meal will provide nitrogen for a longer period though, so it may  end up being a good choice in the end.
The sad analysis for all of this, however, is that there really isn't a good, principled organic way to do this (that I've found -- please tell me if you know one) on a relatively large scale.  You can use your own urine to provide the nitrogen for a small garden, if you can be bothered to collect and spread it.  This approach reportedly can provide enough nitrogen for a family garden grown in dirt, so it may work as well for a straw bale garden given a little extra lead time.

The problem with all of the commercial sources of nitrogen is that, as far as I could determine, there isn't a way to get these materials from sources that follow sustainable practices.  Blood meal is a byproduct of factory meat (which carries multiple drug resistant pathogens), alfalfa is almost guaranteed to be GMO and hence soaked in Roundup, and cottonseed meal is dripping with pesticides.  This is the sad state of our society -- you can't even buy stuff that will rot without worrying about long term damage to your land, health, and environment.  I'm not sure which is the best of these options, but if I were to do it again I'd probably do the urine approach as much as possible, and then try alfalfa to fill any fertility gap.  By the way, if the thought of using human urine on your garden makes you squeamish, I'd recommend reading a little booklet called Liquid Gold -- there's a lot of very interesting information in there about just how silly it is to flush this resource into drinking water...

But I digress.  I have elected to spread soil on top of all of my bales, as you can see in the picture.  I did this because I didn't have time this year to make proper transplants, so I'm going to be direct seeding everything.  I figured that an inch or so of topsoil on top of the bales would benefit the seed starting process by regulating temperature and moisture for the little seedlings.

I used "Evergreen" topsoil, at a cost of $1.16 per bag.  A one cu. ft. bag will put an inch thick layer of soil over about four bales, so you can calculate accordingly if you decide to try this.  I haven't seeded them yet, so I can't report anything about sprouting rates... that'll come in a future post!

Potato Cages

In other garden news, I've been reading Introduction to Permaculture, by Bill Mollison (I *highly* recommend reading this book), and there was a potato raising technique in there that I simply had to try out.  This is a vertical gardening technique for raising potatoes in limited space, with very little effort.  The basic process goes like this:
  1. Cover the ground in a 3 foot diameter circle with newspaper or cardboard.
  2. Put up a cage of some sort over the cardboard.  I used vinyl poultry netting because it was the absolute cheapest material I could find on short notice.  This does not need to be strong, so anything you have on hand that could support a pile of straw will work.
  3. Put about 8 inches of straw mulch in the bottom.
  4. Plant your potatoes
To plant your potatoes, scoop the mulch aside from a planting spot, poke a hole through the cardboard with a knife, put a little pile of soil over the hole, put the potato on the soil, and cover it all back up with mulch.  You should space the potatoes about 8 inches from each other in all directions.  As the plants grow, add more straw mulch to the cage so that only about four inches of plant at the top is actually out of the straw.  The potatoes will develop right in the straw, and will be ready for harvest after the plants flower and wilt.  Since they grow right in the straw, they don't get damaged from digging them out and they come out clean!  I'm planting five pounds of Yukon Gold seed potatoes this way, and will probably do some russets and reds as well.  I'll let you know how it works!

Here's a shot of my four potato cages, primed for spuds and ready to go.  It took about an hour to put them all together, which is WAY faster than the old dig and prep way.  If this works it'll be a fantastic technique to add to the repertoire:


  1. I've been seeing the use of human urine in the garden around the blogosphere lately....don't think I'd ever go there.

  2. Im not sure what the success of this would be in tandem with your hay bale idea here, but you could try to grow some nitrogen fixing legumes (peas, or clover etc) during the process. And cutting back the legumes to provide some green cover over the bales may help with maintaining moisture levels.
    Or invite some friendly chicken around for lunch, They'll love to get into your weeds and leave little drops of the sweet nitrogen filled stuffed everywhere.

  3. @Lou: I think the legumes would be hard to work in combination with the straw bales, but that is certainly an excellent strategy for an earth garden.

    You're right about manure, I expect it is an excellent option if you can get it from a facility that doesn't medicate their lifestock (trickier than it seems...). I wanted to try this, but never got around to asking my friend for a load of his chicken manure. I was too skittish about getting it from unknown suppliers this year because of the threat of various chemicals contaminating it (aminopyrolids from grass-eating animals, and various antibiotics, wormers, and hormones in other animals). I'll definitely try it next year though, if my friend is willing to part with some of his "gray gold".

    Thanks for the tips!

  4. I am intrigued with the potato cages. Could you do other root veggies this way?

  5. @Linda: I'm not certain, but I believe sweet potatoes can be raised this way as well. I think the key is that it needs to be a vining plant that produces tubers wherever it touches ground. Potatoes and sweet potatoes do that and there are probably others I don't know about. It might also be possible to grow things like beets and carrots in straw -- I'm doing some experimenting with that this year and I'll post some updates with my results.

  6. Hey Erik,

    I recently found an organic fertilizer recipe on MotherEarth that I will be trying as side dress fertilizer on my bales. I have a much smaller operation(way smaller..only (2)12 ft bale beds for tomatoes) but this is my 4th year of doing so. Here's a couple of things we found out after the first year:
    1)Surround your bales with something-to keep them from drying out. We used treated wood after researching and finding that the new way wood is being treated no longer involves arsenic. And studies have noted no leaching occurs at any rate. Now that ours are surrounded, we water with and average of 1 gallon of water per plant per week...which is minimal to say the least. We've found once the bales are saturated and surrounded they retain moisture much better. 2)Because water/nutrients easily leak through the bales- you do need to fertilize with something fairly often. 3)As the bales slowly decompose down- you will need to figure a trellis of sorts for your vertical plants. We used a wooden trellis in the past but this year we're going to try tomato cages. The wooden trellis has been great but it is labor intensive to install. While the cages will be easier, I am concerned about them holding up the plants. They get laden!

    I'm doing potatoes in a raised bed but I like your poultry cage idea and definitely will try it next year!

  7. Lantanalane2: Thanks for all that great info! I haven't had a problem with drying lately -- we've gotten 24 inches of rain in the last month (20 times the normal amount). Right now I'm trying to figure out how to plant anything *not* in a straw bale, because my whole place is a swamp!

    I'd love to know more about the fertilizer recipe you mentioned -- there was an article in Mother Earth News about homemade liquid fertilizers, is that the one you are talking about?

  8. Wow that's a lot of rain! Here's the link to Mother Earth, looks like you are already using 1 of the ingredients...the seed meal. After reading your analogy of the "meals" above I'm not sure, if any I find will be chemical free. Currently I'm in process of locating all the ingredients here to make it and hoping our Farmer's supply will have everything. I'd be willing to try the urine next year to get the bales jump started. Even after doing the fertilizer prep our bales were still pretty stiff when we planted this past weekend. But I know they will soften even more in the coming weeks

    You can check over on my little blog- nothing special but I do have some nice 2009 pictures of my harvest. I was very pleased considering how small my set-up was. Just goes to show you how you can straw bale garden in a small space without much ado. You can try most anything in the bales. I've had squash, gourds, cukes, peppers and of course tomatoes seem to be made for them! Beans did not do well however. Here's the link:

    I'll check back often to see how it's all coming along. Good Luck!