Answer: It will still work for the prescribed amount of time - 3 months if exposed to sunlight and air. One of the reasons for scraping it into the soil is to keep it from running off if the soil is puddled by the sprinkler; to keep birds from thinking the granules are seeds; and to protect it from sunshine. If you can't dig it in, maybe you can toss some compost or peat moss over the top? If not, that's okay, but it will protect your fertilizer investment if you do.
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