I’m in the midst of grading papers for my nursery management class, and something that I’m running across is an incredible number of papers where the students are recommending balanced fertilizers. Why are they doing that? Or maybe an even better question is, what is a balanced fertilizer? A balanced fertilizer is a fertilizer which has three numbers which are about the same, like a 10-10-10. The problem with balanced fertilizers is that they are much higher in phosphorus than what most plants need — at least in relation to the amount of nitrogen and potassium which plants need. Especially here in Minnesota, where there is usually plenty of phosphorus in the ground, this extra phosphorus serves no purpose except to pollute waterways. We have got to break the cycle of just assuming that a balanced fertilizer is the way to go. I get to see a lot of soil tests from old agricultural fields where balanced fertilizers were used for years and years. Usually 10-10-10. What I usually see — with very few exceptions — are phosphorus and potassium levels which are either very high or off the charts entirely. Phosphorus and potassium don’t move readily in the soil while nitrogen does, so every year that you add 10-10-10 in the appropriate amount for your plants needs for nitrogen you’re adding too much phosphorus and potassium. Any extra nitrogen which you add will move through your soil, but P and K will build up year after year (and some will run-off into gutters and drains). So what do I recommend? I like a ratio of about 5-1-2 or 5-1-3 for an N-P-K ratio in a general use fertilizer.