Gardening in urban wastelands

Straw is really cheap and really versatile.  We use a couple of round bales [a cylinder 120cm high and 120cm in diameter] a year as bedding for the sheep when they are lambing. I think we paid €20 each last Spring.  We have friends who have built houses and sheds from the smaller square bales 1050mm x 365mm x 460mm (42″ x 14″ x 18″) which you see at gymkhanas and municipal barbecues. These bales are handy sized [15-25 kg] for lifting but need a lot of extra work to make them into vertical walls that won't blow over when the wolf come visiting.  There are effectively no ISO standards for straw, just a wish-list for size, density, straw-length, species and moisture content. A baler can pack the straw light - if it is for sale per bale; or heavy - if it's for the baler's own use and needs to be stored efficiently in his barn.

We've been on our farmlet for 20 years this Spring. We were the first people in the valley - in the parish! - to grow lollarossa [L because red] lettuce:  people would walk up the lane just to gawp at the peculiar. We've been swayed by a lot of experiment and fads & foibles in our efforts to grow things in the peaty acid soil that we are blessed with. It's quite diggable down to between 30 and 60cm and then there's an abrupt transition to a sandy yellow clay which is like poorly set concrete.  Nevertheless, digging in gardens is hard work and upsets the soil microbes: crying "Jaysus, where's all that oxygen coming from?" before keeling over. For a couple of years we were persuaded to try no-dig straw-mulch potato growing. The instructions were to lay out your seed-potatoes (in a mandala or a woowah spiral, naturally) on any piece of ground and cover them over with 30-40cm of weed-suppressing straw,  Experience learned us to mow any grass, nettles and thistles before applying spuds direct to the ground and to dig out the dockens Rumex obtusifolius because them buggers can grow through the sole of your boot if you stand still. To be honest, the yield was not great even after those treatments; I think the poor roots used up a lot of energy penetrating the hard-packed soil. So it's better to at least hack up the top of the seed bed before applying the potatoes.

Still we were better off than we'd been in some previous gardens where the good earth was about 8cm deep over an archaeological dig of old bricks, shards of delph, and broken bottles.  It was with a frisson of empathy, therefore, that I read about straw bale gardening in Philadelphia via Metafilter. The recommendation is to buy as many straw bales as you can afford and water them well, applying some 'fertiliser' [unspecified] alternate days for a couple of weeks. After which you can pop your seedlings into a convenient hole and let photosynthesis do the work. Of course, you should lay out the bales so that the open ends aee top and bottom. The design of straw as a hollow tube works well for wicking and storing water.  If you can't afford 'fertiliser' it's probably a good idea to pee on the bales because straw is quite nitrate-deficient; but go easy - urine is salty.

Some of the comments on the Metafilter page express worry about toxins in urban soil - Victorian paint factory round the corner etc. - but the contaminated soil is 450mm from the base of your lettuce if you plant on top of a straw bale. The added urine nitrate, the penetrating plant roots, and the arrival of fungi in a nicely moist environment push on the decomposition of the straw, so that at the end of one or two seasons, you've generated a pile of compost in the form of a nice friable loam.  You can use this for potting up next year's seed . . . and !shazzam! you have a sustainable kitchen garden which will see you through Armageddon.