I like to use blood meal as an organic nitrogen source for conditioning the bales. Another option that works well is feather meal. Whatever source is used, it should have a minimum of 5% active nitrogen content. Manure will just not work quickly enough, it doesn’t have enough concentration of active nitrogen. With manure it becomes physically impossible to drive enough material into the bale to feed the bacteria enough nitrogen to allow them to colonize the bale. The only exception to this no manure rule is with chicken manure that has been collected without any bedding material or wood shavings mixed in. The manure must be composted for a short 6-12 week period and covered during this time to avoid having rain leach the nitrogen content from the manure. Use this chicken manure in combination with a known concentration such as blood meal or feather meal, and the chicken manure can prove effective and strong enough in nitrogen concentration to achieve the objective of feeding enough nitrogen to grow bacteria quickly inside the bales. DO NOT USE any other manures, they are simply not high enough in nitrogen content and the bales will not condition quickly enough to be ready for planting in the 18 day period of time we are allowing for this to happen. If you want to add a nice layer of weed seeds to your bale surface just use some horse manure or cow manure on top of your bales. Compost has less than 1% nitrogen content, compost tea has less than 1% nitrogen, so don‘t try to condition the bales using either one. Fish emulsion is great but not economical to use in large quantities for bale conditioning, it also stinks horribly. My suggestion for anyone who wants to do Straw Bale Gardening organically is to stick with blood meal or feather meal. One tip is to use a sharp stick or pipe to make holes in the bales when you apply the blood meal, so it works quickly down into the interior. This trick will make the blood meal available to the bacteria more quickly and it will keep the smell at a manageable level. The blood meal will stink a bit like dead animals, since it is made from the blood of dead animals I guess this kind of makes sense doesn’t it. Look for blood meal at a farm supply store where a large bag will cost much less per pound than a small bag at a garden center. You will need a large amount to do the job, and don’t skimp on the amount you apply or your plants will suffer.
We prefer to have the cut side of the bale facing up. The open stem ends allow easier penetration of the granular fertilizer and the water is better able to carry the fertilizer into the bales that way. But if the cut side isn’t up, it isn’t a deal breaker, it may just take a bit more time to work the fertilizer in. I think it is important to keep the strings on the sides of the bales. If the strings are made of sisal or hemp twine, this is really key, as if the natural fiber is touching the soil it will likely decompose and break, allowing the bale to loose its compression and even fall apart. One key to the quick decomposition of the straw and the conditioning is that the bales must be compressed. If the straw is loose or not well compressed it will decompose much more slowly, possibly too slowly for our purposes. If the strings are running along the top side of the bales, and you are stabbing into the bales with a sharp planting trowel to make holes for planting bedding plants, it is likely that a string could easily be cut. If that were to happen it would be important to retie that string as tightly as possible. Most bale makers, or balers, will make bales with two distinct sides, the cut side, where a knife simply shears off the straw stalks on one side and the other end of the bale is folded over inside the baler. It is easy to see the difference, and any farm kid who ever stacked bales on a baling rack knows the difference is distinct. If you pick up the bales with the cut side bouncing against your leg when you stack them, it hurts, and you’ll have a serious rash on that leg before you know it. If you are a city kid, then you might not realize there is a difference, but once you see another bale, you will see the difference, so remember to put the cut side up. If by chance the cut side is also a side with the strings, then turn the bale to keep the strings on the sides of the bale. You’ll also see that the strings on the side help to hold the poly tents from the straw bale greenhouse covers in place.
No, mold is simply one of the tools mother nature uses to decompose organic substrates. Mold growing inside a confined space, where we breath in the concentrated spores, is very potentially harmful. Absolutely mold growing in your home is not healthy. Plants growing in a bale with mold on it are completely unaffected and actually benefit from the mold as mold is a decomposer, helping to break down the substrate into soil. Plants don’t breathe in and out like we do, so the mold doesn’t affect them at all. Mold growing on a bale will usually be attacked and consumed by the bacteria present in the bale shortly after it gets established. If a gardener has serious allergies to mold, then I would recommend wearing gloves, and a mask when gardening period, with bales or regular soil. If allergies are bad enough then maybe gardening in general just isn’t for you, stay indoors where your less likely to suffer any encounters with mold spores. Soil generally contains lots of mold spores as well, as does most air outdoors in the summer. The concentration is much lower than indoor air can be in a moldy house however and the lower concentration of spores is typically never a concern for most people. I would not recommend eating vegetable leaves with mold on them, for instance if a lettuce leaf came into contact and was smeared with mold prior to harvesting it, then I would suggest washing it well before consuming it. We eat moldy cheese all the time, they even charge extra for the moldiest of cheeses. Most mold itself is pretty harmless, but less than tasty to eat. Think about your straw bales like cheese, the moldier the better. Stop worrying about what you assume is going to go so terribly wrong with your Straw Bale Garden, and just get started. You’ll see that most of these concerns you have about moldy bales are completely unwarranted in the end.