Answer: Based on your description I am not certain what the problem would be. Anaerobic conditions in compost or mulch piles can cause an ammonia type smell; this is usually due to being too compacted so there is too little air, or due to being too wet. If you recently spread poor quality mulch, it might be wafting off of that and should go away in a day or two of fresh air. Or, it might be related to waterlogged conditions, especially if you spread a high nitrogen fertilizer recently. It also occurs to me that if you have a septic system with drain field in those areas, you might want to have it checked out. You might also want to consult with your UMAss Extension or UMass Master Gardeners to see if they can give you a more specific answer.
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