I remember seeing a documentary on hay harvesting and the original use for that piece of equipment was in the paper industry. They use it to move large rolls of paper about-then it was used in the flooring industry to move rolls of carpet and linoleum around. Each used some modified version of it. As a boy I remember setting on the international harvester baler and tying the twine as the bail was compressed. Those were the fun times that later grew in to dreaded have to do work in my later years.

I doubt if the rotting hay got hot enough to destroy many seeds.

The difference in hay bales and straw bales is that the straw could be full of weed seeds depending on what kind of hay it is. That's especially true if the hay is from native pasture land with a variety of prairie grasses and forbs. We have friends here in our rural location that frequently gift us with old, spoiled hay that I use in my compost pile and as mulch in my garden beds. Weeds will sprout from that hay and you have to be aggressive about pulling them quickly or they'll take over. How quickly you feel a rise in the temperatures inside the hay will vary depending on how old or how fresh it is. About this time last year we got 206 bales of old hay that was only 6 to 8 months old and those bales weren't decomposing inside yet. However, when I broke some bales apart in January 2012 to use as mulch on the dogs' muddy pathway in the dog yard, those bales were pure compost in the center and were smoking hot. The bales I've been breaking apart to use as mulch in the veggie garden since then also have been compost in the middle and really hot. If your bales are really old, they might already have decomposed to some extent inside. Most hay bales don't last but 2 to 4 years even if kept inside a barn. If you have allergies to mold and fungi, be careful when breaking open the bales because once they're wet, they are prone to have mold and/or fungi in them. Depending on what kind of wildlife you have in your neighborhood, you may have issues with field mice and snakes and some insects getting into your hay bales. Here where I live we have tons of wildlife and the mice and snakes love the bales of hay. We have friends with cattle dogs that have been bitten by rattlesnakes that climb up into/onto the bales of hay. I have to be really careful and watchful when breaking apart bales of hay in the spring and summer because of the snakes and scorpions here. That won't be a big issue if you're in a pretty urban area where venomous snakes are rare, but you also may find scorpions and fire ants in your hay bales if those are common pests in your area. It is easier to raise plants in bales of hay or straw in a wet year than in a really dry year like last year. In a really dry year, they dry out too quickly. Judging from the weather we are having now, this ought to be a good year to grow in hay bales.

catwhisperer2009 Actually the interview is in three segments and I linked only the first one. The other two can be accessed by running your cursor over the thumbnails just under the clip when it's finished. I had totally forgotten, but apparently she was such a free spirit she gardened in the nude, as she recounts in the third clip. Additionally, she says she helped Carrie Nation chop up saloons with axes. She was also fiercely independent and did not believe that anyone had a right to tell others what to do about anything, herself about gardening included. Well, maybe with the exception of chopping up saloons... She just wrote and talked about what she did herself.