Strawbale gardening trial: April to September 2013

Earlier in the year I’d been reading a lot about what great success some people were having with strawbale gardening (e.g. here, and here, and here), and came across the detailed instructions prepared by the Division of Agricultural Sciences and Natural Resources at Oklahoma State University, available as a pdf file here.

So I thought I’d give it a go, even though I couldn’t immediately see a need for strawbale plantings on our patch.  We aren’t short of space.  Having made the decision to limit our footprint on our 35ha to the area uphill along the ridge-top from the house, we have the potential to occupy a couple of hectares.  And we don’t have a soil contamination problem.  However we do have soil issues – for the most part we don’t have what you’d call “soil”, but rather decomposing sandstone with some soil-like features.  So maybe from that point of view we resemble those with concreted over yards who see strawbale gardening as one of only a very few options.

1 April 2013 – Putting the bales in place

I decided to use a more or less flat area which was scheduled to become our fourth shadehouse in due course, but certainly not for many months.  So as not to get in the way of ongoing work constructing shadehouses numbers two and three, I limited myself to just six straw bales.  They were arranged in pairs with one of each pair on its wide side, and the other on its narrow side (i.e. with the straws running vertically).20130401_P1050510_blogBarley straw is what I had on hand, and is what I use by choice.  Lately it has been costing $10 per bale, no matter what the season, so the original cash outlay was $60, not counting the relatively minor cost of the blood and bone.  It isn’t actually blood and bone; the pure blood and bone meal that used to be available 60 years ago when I was growing up on a farm doesn’t seem to be available any more, so it was the “blood & bone based fertilizer” type of product.

7 April 2013

The bales were thoroughly soaked twice per day for three days, then had urea applied daily for a further three days.  Since urea is an industrially produced compound, and it has to be bought with real dollars, I decided to use urine, since the main ingredient in urine (after water) is nitrogen (15-18%) most of which is present as urea**.20130407_P1050540_blogThe bales were moved closer together, but still in their original pairs, to save space, but then I realised that I could make an arrangement that had a rectangular hole in the middle which would be a good place to plant some potatoes which had started sprouting.  I put a base of flood-deposited creek sand in this middle space, and just covered the potatoes with this.  The space was approximately 0.5m x 0.8m – that measurement becomes important later on.

The flood which deposited the sand occurred when we had a major rainfall event just after a bushfire (forest fire) that burned out the whole of the catchment above our creek crossing (and 5,000 ha in total across the Hills – you can see details of it on the Smokespotter website).  As a result, there was no vegetation to slow the runoff of the rain to allow it to soak into the ground.  Pretty much every drop that fell ran off into the creeks, causing a flash flood that carried huge quantities of sand, charcoal and humus which was deposited wherever there was the slightest backwater, such as the approaches to our creek crossing.  I shoveled two large trailer-loads of this rich and free resource off our track and stockpiled it for making potting mix.

17 April 2013

Following the urea treatment the bales were subjected to three days on which watering was followed fertilizing with the blood and bone product. At the end of this period the bales were given a very light dusting with the creek sand – intended to prevent the seeds from falling too far into the spaces on the “edge-on” bales (or even washing right through them).

20130417_P1050588_blogAfter this they were seeded in strips across the top of each bale with lettuce, flat-leaf parsley, pak choi, corn salad, silverbeet (swiss chard), coriander (cilantro) and kangkung (water morning glory).  Both bales in each pair had the same plantings.

Unfortunately, just after the seeds were planted we had a heavy rain that washed some of the sand off the bales, and quite likely some of the seeds as well.  This may be why there was no germination of kangkung, and little of the silverbeet, as they were on opposite ends of the bales.

31 May 2013

By the end of May, some five weeks after seeding, there was only limited growth of some seedlings.  In general all species showed uneven sprouting, with some seeds coming up well in advance of others.

20130531_P1050876_blogYou can see two stalks of a Coprinus fungi in the foreground.  At about this stage these fungi became very numerous, and persisted for a couple of weeks.

20130531_P1050875_blogEverything is looking fairly healthy at this stage, and no insect damage.  More stalks of the Coprinus fungi are visible to the right, and in the foreground of the photo below you can see a black area which is typical of the residue this fungus leaves when its cap decomposes into a sticky black mass.  We were wary of eating any of the plants which were affected by this.

20130531_P1050878_blogThe corn salad was among the slowest to come up and germination was rather patchy, but it isn’t known for its high germination rate.  In the end the corn salad proved to be the second longest producer, after the parsley, but the volume was not great because they didn’t grow to their full potential.

At this stage I first noticed some tunneling into the bales by rats or bandicoots.  I tried trapping them, but without success.

29 June 2013

20130629_P1050991_blogIt’s all looking very healthy here, but that was only achieved with daily doses of nitrogen in the form of diluted urine (1:10) carefully applied under the foliage.  You can’t see it in the photos but snails were a major problem, particularly on the lettuce, and it was unusual to pick any lower leaves without at last two snails attached.  I’m sure that the damp and decomposing straw provided an ideal habitat for snails, and this seems to me to be one of the drawbacks of strawbale gardening.  The tall leafy growth to the left of centre in the shot above is the potatoes.

20130629_P1050992_blogSome insect damage was beginning to become apparent, but this seemed to be restricted to the pak choi and the potatoes, which can be seen here, on the right, beginning to overwhelm things planted on the bales.  I hadn’t realised how tall the potato plants would grow, and it is possible that they had more leafy matter than usual because of the high levels of nitrogen in the water applied to the bales.

29 August 2013

20130827_P1060075_blogFour months in, we’ve been harvesting for nearly three months and I’ve discontinued the daily nitrogen application (mostly because I was too busy, but also it became impossible to keep up a sufficient supply of nitrogen, particularly as the bales disintegrated and water tended to flow right through).  The pak choi is fairly dominant at this stage, and we are harvesting leaves, stems, buds and flowers for use in stir fries and salads.  Pak choi has two distinctly different leaf types. The first leaves are wide, slightly hairy, and have a slight “peppery” flavour that becomes stronger as the plant ages.  Once the flower stems grow they develop different leaves which are thicker, have no hairs, and are sweet-tasting.  At this stage, before the flowers open, the stems are tender and sweet, as are the bud clusters.

20130829_P1060093_blogThe lettuce are in the middle of the right edge.  It is clear that some are yellowing as a result of nitrogen deficiency.  What isn’t obvious is that all of the lettuce are “stunted”; I had transplanted about ten lettuce seedlings from the bales to a normal garden bed, and within two weeks they were more than twice the size of those left in the bales.  I tried to remedy what was clearly an overall nutrient deficiency by making up compost teas with worm castings, and adding both the tea and the rich “sludge” to the bales, but though individual plants made significant gains, this didn’t result in any overall improvement.

The curly parsley in the middle was planted into the bales with its potting mix, as were some spring onions.  Both did really well, no doubt partly because of the nutrients in their accompanying soil, but in my experience both parsley and spring onions are incredibly hardy.

The potatoes had pretty much died off by this stage, leaving the bare soil in the middle.  I didn’t attempt to harvest any potatoes because of not wanting to disturb the collapsing straw bales.

17 September

Time to take stock, and to harvest the potatoes.  The above ground stems had been dead for a while, but I didn’t want to disturb the pak choi which had fallen across the potato area until its seed cases were ready to harvest.  However today curiosity got the better of me.  So I pushed the pak choi aside, noting as I did that where they had collapsed onto their own bales there was still harvestable corn salad underneath.

It didn’t take long to find the first potatoes, though they were rather small.  Not encouraging.  But as I dug deeper they became bigger.  In the end I got 2.5kg of very nice Dutch Cream potatoes out of this “pocket” between the bales.  Not bad for something that was planted as an afterthought.

P1060125_smallRemember the dimensions of this area?  0.8 x 0.5m – or 0.4 square metres.  Now if I could get the same production out of a hectare of potatoes, I’d have ….. 72.5 metric tonnes of potatoes from a one hectare field!!!  Not that I think I could easily replicate this over one hectare, but

The amazing thing is that I put nearly zero effort into this potato area, though I did water it daily as part of the straw bale watering, and it no doubt benefited from the thermal insulation provided by the straw bales and from the blood and bone and urine applied to the surrounding bales (though this run-off represents very little fertilizer in broadscale agricultural terms).

But … getting back to the strawbale gardening.

What were we still harvesting from the strawbales after five and a half months?  Here’s the list: corn salad, flat-leaf parsley, curly parsley and spring onions (both transplanted into the bales back in June), silverbeet (small leaves from three or four plants), and leaves and flowers from the pak choi stems.  And the potatoes.  And in the end there will be a huge crop of pak choi seeds, plus the rotted down straw bales to use as a soil supplement.

Was it sustainable?

On a quick assessment I’d say it was pretty sustainable. The straw bales were from the Toowoomba region where there is a significant production of barley for malting.  That’s only 40km from here.  The minimal input of blood and bone based fertilizer came from much further afield (I’m not sure where), and the urea was produced very locally, being derived from our urine.  The creek sand for the potatoes came from our creek, only 1km from the garden, and wasn’t taken out of the bed of the creek but was flood debris (sand, humic matter, charcoal) deposited on the creek bank.  The water was collected on our roofs and stored in stainless steel tanks (recyclable at the end of their life, which galvanized tanks seldom are).  A minimal amount of pumping using a petrol driven pump was used to get the water up to a header tank, from where it was gravity fed to the garden tank. From there it was pumped to the strawbales using a solar electricity-powered pump.  The seeds for the crops were either from our collection or from Green Harvest in Maleny, around 100km away, and delivered by post.  The seed potatoes were organic potatoes that had started sprouting in our kitchen.

Is it worth doing again?

On a cost basis I’d be inclined to say that the production hasn’t been worth the $60 for the bales.  But then when I think about the ongoing organic production we have had in a number of crops and the fact that the remains of the bales can be used as a soil additive in a new garden, the equation starts to look better.

On the time/effort side of things, I had been thinking for quite some time that the harvest wasn’t worth the effort that I’d put into the preparation of the bales and the continual (for the first two and a half months) watering with diluted urine.  However, in preparing this blog post I realised that, while there was a considerable initial investment in effort to “condition” the straw bales and to prepare the diluted urine application in the early stages, the ongoing watering and fertilizing pretty much fitted in with the same treatments of other areas in the garden.

So, all things considered, it was surprisingly productive, if not totally cost effective.  For someone with no good soil and plenty of time it would be a good way to grow leafy vegetables.

I’ll certainly do it at least once more, but with a different setup: four bales forming two parallel lines and one bale across each end, so as to have a long narrow potato production area in the middle and production of other crops on the tops of the bales.

In part this will be to see if the potato production can be duplicated, and in part it will be to test the strawbale approach in the hottest part of the year, given that the original trial was over the winter.  I doubt that this will become part of our production process, but it may yield more lessons that can be incorporated into our approach.

** Jenkins, The Humanure Handbook Table 3.2; Steinfeld, Liquid Gold.

One thought on “Strawbale gardening trial: April to September 2013

  1. Pingback: Ruminations on potato production and small-scale vs broadacre agriculture | Sustainable @ Lockyer Valley

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