I cannot attend the public hearing since I will be teaching in MN. Please forward this information so it can be presented at the hearing.

When fertilizer is properly applied, there are no data that show P in fertilizer runs off from turf. Exceptions are: when it is applied to saturated soils followed by a heavy rain or when it is applied to paved surfaces. Dr. Kussow's work shows that over 70-80% of the total runoff and total P in runoff occurs during late winter/spring when snow melts or it rains on frozen ground. The P in this case is especially not likely to come from fertilizer but to be leached from plants. The amount of P fertilizer applied has relatively little effect on the total amount of P in the plant, which is generally less than 0.5% on a dry weight basis. Current forms of various bans around the state often include exemptions for when soil tests indicate P is in short supply or for new establishments. Unfortunately, our soil tests were not developed for turf density but rather for agricultural yields. Studies show a dense turf stops soil erosion which often carries up to 70% or more of the P load in runoff. P applications are generally quickly adsorbed by soil: at high pH much is complexed with Ca, Mg into non water-soluble forms; at low pH it complexes with iron and aluminum, also non soluble and therefore unavailable for plant uptake. P fertilization is sometimes also needed when soils are cold (spring) and P is tied up more than during warmer temperatures. It may also be needed to regenerate new roots/foliage following root damage from insects (white grub) or disease (take-all, summer patch, necrotic ring spot, etc.).

Dr. Kussow and I have never advocated applying something where it's not needed. There are many cases where P may be being applied where it's not needed, but there is also no evidence that this is causing a problem. Some proposed regulations, including Dane County, may allow natural sources of P to be used. This actually could cause a problem for 2 reasons: 1) Particles are lightweight and much more likely to float away in runoff, and 2) The ratio of P to N is much higher than with most synthetic fertilizers (the exception being starter fertilizers), causing 2-3X or more actual P to be applied in order to get sufficient N to the turf. Most of our turf fertilizers have a high N percentage (e.g., 20% or more) and a low P percentage (3% or less). One unintended but likely outcome of P restrictions will be a reduction in the amount of fertilization of urban landscapes which will lead to thin turf and more runoff, including more P, as it leaches out of the remaining plant leaves and is carried as soil erosion but won't be stopped due to the thinness of the turf. One wonders if we could actually decrease what is coming off urban landscapes (trees, lawns, etc.) by requiring people to properly fertilize turf for best quality/density, i.e., at least more N. Incidentally, the DNR actually states that "turf should be fertilized to promote optimal turf health" in NR151, its recently completed nonpoint source pollution rules.