EPA’s Fertilizer Rules Earn My Seal of Approvaltesttest
Most of Maryland’s soils are acid. Unless they are limed every three to five years, they are generally too acid for optimum growth, so that any fertilizer applied is wasted and finds its way into the Bay. During the many lectures I give, I always ask who in the audience have had their soil tested in the last five years. I’m lucky to find even a few. Horticulture is a science, not a game for guessing or intuition.
But that is how most homeowners and even many lawn companies apply fertilizer to their grasses.
Which is why I applaud the Environmental Protection Agency’s decision to restrict fertilizer use in its 2010 strategy to restore the Bay.
I strongly support new EPA’s efforts to remove phosphorus from lawn fertilizers. It is about time that measures are taken to minimize the sale of fertilizers to home gardeners. I only wish the guidelines were stronger, also banning the sale of ultra-high nitrogen fertilizers.
All of the lawn fertilizers currently being sold contain nitrogen (N), phosphorus (P) and potassium (K).
There is so much P in turf soils that it can almost be mined. Phosphorus has a very low solubility and simply accumulates. In over-abundance it can prevent certain essential trace elements from entering the roots of plants. Phosphorus also attaches to soil particles. When they wash into the Bay, it contributes to the high P levels responsible for.
Some lawn fertilizer manufacturers have agreed to offer phosphorusfree fertilizers in the future. As far as I am concerned, that is not soon enough.
Outlets selling fertilizer should require soil test results to assure proper use. None of the fertilizer instructions I have reviewed mention the need for soil testing. In my opinion, no one should be allowed to purchase fertilizers without having soil test results at hand.
There is also some discussion on reducing the availability of fertilizers in the spring. Since most of our turf grasses are cool-season grasses, including bluegrass and fescues, the sale of lawn fertilizers for these grasses should be limited to August, September and October.
Now is also the time to ban the sale of ultra-high nitrogen fertilizers. On a recent trip to a garden center, I was troubled to see lawn fertilizers containing 32 percent nitrogen. That is more nitrogen than the roots of grasses can absorb, even though half is in a slow release form.
Having spent many years researching the effect of high levels of nitrogen on potassium uptake, I am not surprised that many of the lush lawns I see are affected by a disease called fusarium. True, nitrogen stimulates growth, but high levels of nitrogen create succulent plant growth that is susceptible to many problems.
What also concerns me is that many of these high-nitrogen fertilizers are being applied at the same rate as low-nitrogen fertilizers such as 10-6-4. This means that three times more nitrogen is being applied than needed. This is further compounded by inaccurate fertilizer spreaders. Older spreaders apply more fertilizer at the same setting because the holes that it flows through enlarge with use.
Some producers say that their fertilizers contain liming material to counter acidifying effects. Nonsense! There is too little liming material in these fertilizers to correct soils that are much too acid for efficient utilization of plant nutrients.
People are quick to blame farmers for polluting the Bay. Yet turf is Maryland’s No. 1 crop, exceeding corn and gaining on all row crops combined. Excess lawn fertilizers flow into storm drains and nearby streams. Nitrogen not utilized by the roots leaches into the groundwater and wells and aquifers.
Lawn-growers amateur and professional need to look at who’s calling the kettle black.