A neighborhood cat has been doing its poop business every night into the top soft inch or so of compost/soil layer I laid down and seeded with grass seed, hoping to get a lawn to grow in my 60 ft x 60 foot backyard. Since planting several days ago and awaiting eventual germination of the grass seed, each morning I see that the cat has scratched up a different spot and did it's dump. It's a seven or eight foot high fenced in yard with pickets spaced every four inches or so. I took the effort of installing/securing some strong vinyl mesh netting from ground level up to 3 feet high on the fence, hoping that would prevent the cat from crawling in through the pickets, but still the cat is managing to enter somehow so that deterrent is just not working.
Any suggestions on a method to deter this cat from from doing this? I know there are those different electronic gadgets that are supposed to work to prevent this kind of thing but do they really work, or is there something else I can try before shelling out bucks for one of those gadgets? It's obvious the cat will continue this habit in my seed soil unless I can do something stop it.