My husband is starting to warm to the hugelkultur idea but now is suggesting that instead of wood and brush we trench and put a row of bailed scrap hay , would that work
goal is to improve the soil which is very rocky and a bit clay

has any one tried this ?
would me in south eastern ma USA

If you do it right it will be like growing on top of a compost pile. But there is a chance it could go anaerobic from using up the oxygen and then you will have a huge problem.

What kind of hay? It could be a nitrogen sink if it is straw or grass hay, but if it is alfalfa or clover there should be plenty of nitrogen.

It will probably break down faster than wood, so it is only a few years before it is completely gone--but you should have good raised beds with better soil.

What is the end goal? If it is annual garden beds, I say go for it and use a broadfork to keep it aerated if needed. If it is perennials and trees, then I would be more hesitant. Trees can have real problems if you put unfinished compost under them and it collapses--it creates a kind of sinkhole or cavern and the tree roots air prune around it.

weather we use wood -hay or a combination I was planning a for depth of about 1 1/2 or 2feet down and 2-3 feet above soil level( because I know it will settle after a few years so that we end up with deep organic reservoirs of in ground compost this will be to plant vegetables and flowers and I am thinking of possibly broadcasting white clover to plant through this planting area gets very wet in the spring but hard as a rock and dry in the summer and has only been used a few years . it is also the furthest from the hose and very hard to water ( we have to carry water or go buy 100 or more feet of additional hose .
This is my way to try to go more no till ( my husband is from a farm family and wants to drive the tractor over every thing and I would like to encourage worms with more permanent beds , that are like plant-able compost piles so I do not have to wait so late in the season to plant . ( can not use the tractor while the ground is wet but I could plant in the raised part of the bed in March or April .)

the fields we have available to bale are grass and weed see picture ( this photo was from the middle of the field the other half is more dried fine grass ) ,

your point was just what I wanted to get input on. so we should definitely incorporate wood to prevent packing ( we do have lots of fresh uncut and old dry brush but for some reason my husband is interested in testing with hay )
so I am thinking we should also add some manure with the hay and brush , then cap with compost and the removed soil

The distance to water would be a reason to use wood and make a hugel bed. Without it you have a humus rich raised bed which is not bad by any means.