Jo's potato experiment

Last Spring Jo decided to do an experiment with various methods of growing potatoes in her garden at Geilston Bay.  In this blog post she describes what she did and what she learnt.

I planted spuds over an 8 week period so there are some variables with different weather and time, but this was more about varying the date of maturity than anything else, and of course I am never as organised as I would like to be to plant them out all at once.  

I planted 500 grams of potatoes, roughly 8 – 10 spuds, using the following 4 methods:

1. Soil - this is brought-in soil, quite sandy.  I added layers of straw and sheep poo and watered well.  I don’t consider this soil to be particularly healthy.  It has no worm life, and like I said, is sandy, but then again, some of the best spuds come from South Arm sandy soil.
2. Tyres - soil only. As soon as I put a tyre stack together I realised the restrictions with planting this way.  You can’t 'bandicoot' any out. 
3. Compost bin - I used a black compost bin and filled it with soil.
4. No dig method - newspaper on the weedy ground, spuds on top, then layers of straw, sheep poo, straw, mushroom compost and soaked in.

The first spuds that went in were the ones in the soil.  This was late July.
Two weeks later I put spuds in the tyres.
Two weeks after that I put spuds in the compost bin.
Four weeks later I planted spuds using the no-dig method.

The spuds in the soil and tyres took off.  The greens coming through were thick and deep green and very strong looking.  

I abandoned the tyres when the greens were about 10 cm high because, when I mentioned on our Facebook page that I was using tyres, I got quite a reaction.  People posted lots of articles about the leeching of chemicals from tyres.  In 2004 growing vegetables in tyres was presented on the Gardening Australia program as a good way to re-use old tyres.  However, on its web site the ABC now says 'since this story was made, research has suggested that growing potatoes in tyres risks chemical contamination of edible tubers. The method is no longer recommended. September 2010'
(see http://www.abc.net.au/gardening/stories/s1059566.htm ).  More info on this subject can be found for example at http://www.brightonpermaculture.org.uk/news/11-news/363-growing-food-in-tyres.html

I was grateful that I was warned and decided not to continue with this method.  I abandoned it just as greens were breaking the surface.  I replanted the spuds inside a chook-wire tunnel, but they did not recover.

Around early November the chooks got into the soil spuds and scratched around a lot.  A few tops died off then.  This was a variable I had not factored in!

The compost bin spuds came up thin and weedy.  The lid was off the bin but, because of the combination of striving for light and warm conditions within the bin, the tops continued to be long, weedy and not healthy looking.  Perhaps all the health was happening under the soil!

The no dig spuds were slow to start, in fact I thought they might have succumbed to rot as we had so much rain late last Spring.  When they did come up they looked okay, but not as strong looking as the soil spuds.  Eventually they strengthened up.  I dug them up late March, much later than the other two lots.

How did the yields from the three methods compare?  Remember I planted roughly the same amount in each patch.

Poorest yield was from the compost bin, barely worth the effort:

My spuds from the compost bin

The soil spuds had the sandy soil and regularly needed watering due to the sandy soil.  The soil method came second:

My spuds from the soil

The no dig method gave the best result.  It had the most water being at the bottom of our steep block.

My spuds using the no-dig method

From now on I will stick with the no-dig method, as you get the added bonus of really rich humus and loads of worms.

Thank you, Jo, it is very useful to experiment like you did and share experiences!