U Mass soil analysis suggested 4N/3P/1K needed per 1000 sq ft. for a growing season. The only fertilizer I can find that is close is Ironrite 12/10/10; but too much potassium. Can you suggest what I need to apply to replete the nutrients?
You could use cottonseed meal (5-2-1) or an an all-purpose organic fertilizer (5-4-3). A 10-10-10 fertilizer would be OK to use as well, but the first two options would be better. Any excess potassium will be stored in the soil until it's needed. There isn't so much of a problem with potassium in water runoff as there is with phosphorus. Too much phosphorus is more of a concern, as it's a major pollutant in the Chesapeake Bay. To amend your soil as per the test analysis, you don't have to find an exact match on the nutrients. In general, we recommend going with an organic product over a synthetically manufactured one; the process to fix nitrogen is incredibly resource intensive. Also, with an organic product there is less of a chance of "burning" plant tissue, which can occur from the soluble salts in fertilizers.