Mouldy garlic

Any suggestions for helping prevent mould in next season's crop? It was in the outer layers - the leaves yellowed early once the bulbs got the mould.
We put in lots of hay and chicken poop (from under shook roosting spot) a couple months before planting, to give it some time to rot down.
Grew them in slits cut in weed mat following suggestion from neighbour who's done that for years - and they replanted in the same spot - for last 5 years.

My first thought is your soil may not be draining water adequately and is staying too wet. Overall, how would you describe your soil? And also, how would you describe this mold? Are the bulbs of garlic soft and rotting? Can you dig a spot where a bulb was or still is and describe the smell of the soil?