The weed killer should not be an issue. The horse gut would’ve digested all of that.
Manure, even well composted, still is high in Nitrogen, so things that don’t like/require much Nitrogen would react by under-performing, for sure.
It will correct itself in time, but if you don’t want to waste garden space, and still produce some food this season, try planting:
Lettuces, Arugula, Spinach, Kale, Mustard Greens, Cabbages, Brussels Sprouts, Pole Beans, Sweet Corn or Celery. They all like Nitrogen.
Root Vegetables won’t be happy in high Nitrogen, so anything that produces food ‘below ground’ will still be a problem for you for a while. (Potatoes, Radishes, Turnips, Onions, Leeks, etc.)
In higher Nitrogen, Peppers and Tomatoes and Eggplant and Cukes and Zukes and other plants that produce ‘fruit’ above ground will grow big and leafy, but fruit production will be lacking.
It’s Science! :)
Much to Beau’s dismay, I only top dress our Kitchen Garden raised beds from our manure compost pile every 3-4 years. I’m one that prefers to personally give whatever I’m growing a custom nutritional diet, versus having too much Nitrogen.
Thanks. Good advice!