The large circular hay bales are pretty abundant and are fairly cheap in my area. There are also some coffee places like Starbucks that give out a good amount of coffee grounds on a first come first serve basis each day. I would like to buy one of these hay bales, mix in some coffee grounds, comfrey and a bit of compost from a previous pile to start making compost using the Rapid Composting method. I work at a nursery where we have a large digester that we put massive amounts of leaves into, and use pretty much just coffee grounds as the source of "greens"; but I am curious to know if there is any downside to doing this. Could the compost created be too acidic, or unbalanced in some way? Or are there any other foreseeable problems with this plan someone could warn me of?
Anytime you're just using a few ingredients, you're likely to get some kind of imbalance (nutrient, pH, etc) in the finished compost. The more different ingredients you can put in the better, but that's just not always possible when working at a larger scale where you need huge quantities of everything. You could try fresh lawn clippings (lots of lawn mower men are happy to find somewhere to dump them!).
If your soil tends to be alkaline or your water tends to be alkaline, the coffee grounds in the compost help in that regard. But it's true that overabundance of just a couple compost ingredients leads to too much of some things and not enough of others. Yet it is going to take the nitrogen in the coffee grounds to break down all that straw/hay. Is it hay, like animal feed oat hay or alfalfa, or is it straw, just bedding absorber field leftovers?
you dont have to compost these grounds they are a seed meal and are best used as a direct fertiliser also re the hay if its not spoilt hay then why not raise rabbits or Cuy/ guinea pigs as pets ..or more yummo their double digested manure is the ducks nuts !
most veggie gardens can do with 100g /m2 agricultural grade lime or dolomite per year anyway on most garden soils (buy aglime its ground fine enough to have effect! its cheap as, do it!) on new soils do 150 in the first year more is not more better just to be regular. each year add said lime and soils will adjust well over time easy does it
so.. if you want to compost hay.. remember hay is the devil incarnate as far as weed seeds go! no farmer will be selling you premium hay! its going to be a funky fungal health hazard of a whos-who of allergenic moulds or ist going to be a late-hay full of arch-demon seeds like Vetch, and whatever else the loacal ag officers say NEVER to allow onto your farm if you want relatively clean you are looking for the word 'straw' straw wil have few weeds and most seedlinsg will be the crop species ege peas, oats, wheat, barley, soy hay will be some demon spawn of hardy abundant fecund pasture species you will battle against for eons that said. theres a few ways i know to defuse such a bomb one. hot compost (though vetch will likely survive it!) youll need one of 2 things 1 synthetic nitrogen 2 farmyard nitrogen either will do the job. my own philosophy is you do what it takes to kickstart the system, and thats within the ethics. ill have to dig up the recipes for you ... it has to be enough to generate a hot compost to kill the weeds, and to end up with a finsihed % of 1-1.5% N thats just absolutely super sweet for soil organisms, in fact you can grow button mushrooms on it! and that would be a fully worthy use of the biological energy within. please consult Paul stamets texts on that as well as other mushroom texts by chang et al (consult your state library service or google books for previews) BTW Horse manure is 'cubed hay' treat its as such hot compost or boil it before puttin anywhere near your vegetable garden!
wheat straw is given as 3.9% Nitrogen +/- Hay Soghum 6.4-11.2% Nitrogen vetch 13.3 wheat 6.1 soy 15 rye 8 peanut 10.6 pea 6-14 rhodes 5.7 oat 8.2 so as you can see more bang for your buck than straw by far but it has to be it if needs to get hot by fermentation remember all you are taking as hay comes from a farm somewhere. its nutrient mining from tomorrows food better to use urban sources like lawn clippings and tree loppings Number 2 way to get rid of weeds char it ive covered this elsewhere its wastes a lot of nitrogen and should only be used to dispose of the worst of seeds hay far better than binning it though! fire will carbonize the seeds and add them as valuable input to soil number 3 way put it in the chicken run build a big chook run and dump all a organic matter in there the scratching will trigger germiantion and more scratching and pecking will eliminate any weed plants after a few years youll have a very rich mulch to use, which id stil cover with a clean layer some weed seeds last 70+ years! Bagasse and peanut hulls are the cleansest mulch i know of followed by tree loppings and pea straw Peas traw isnt clean but who ever begrudged a free crop of peas! feed planst to chooks too as greens