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Dick Wolkowski: The pesky element phosphorus

[audio:http://news.cals.wisc.edu/wp-content/uploads/2011/04/dick_wolkowski_phosphorous.mp3|titles=Dick Wolkowski: The pesky element phosphorus]

Dick Wolkowski, Senior Scientist
Department of Soil Science
College of Agricultural and Life Sciences
rpwolkow@facstaff.wisc.edu
(608) 263-3913

The pesky element phosphorus
Time – 3:08

0:15 – What phosphorus is
0:29 – Why phosphorus is so important
1:53 – How phosphorus acts in the soil
1:14 – Why phosphorus is an issue
2:27 – Home and garden use of phosphorus
2:58 – Lead out

Sevie Kenyon

That pesky mineral phosphorus: We’re visiting today with Dick Wolkowski, department of Soil Science, University of Wisconsin Extension and the college of Agricultural and Life Sciences, Madison Wisconsin.  I am Sevie Kenyon. Dick, welcome to our microphone.  What is phosphorus?

Dick Walkowski

Well phosphorus is one of the essential plant nutrients.  It’s what we call a macronutrient.  When you look at a fertilizer label you see three numbers, it’s that second number that shows up.

Sevie Kenyon

Why is phosphorus so important?

Dick Wolkowski

Well being one the macronutrients is extremely important for plant growth and development.  It’s a component of the genetic material of the plant – the DNA, the RNA.  It’s also important in what we call energy transfer reactions.  Plant’s simply can’t live without adequate phosphorus.

Sevie Kenyon

Dick, can you give us an idea how phosphorus acts in the soil?

Dick Wolkowski

Well phosphorus is an element that is tightly held by soil minerals. Phosphorus, because it attaches to soil minerals, really doesn’t move very far. For that reason, it is very important, especially in the spring of the year, to have phosphorus supplied near the seed of corn when that is planted.

Sevie Kenyon

Why is phosphorus such an issue?

Dick Wolkowski

Well phosphorus turns out to be the limiting nutrient in aquatic systems, our lakes, streams, our ponds are deficient in phosphorus. But when phosphorus enters those waters it essentially fertilizes them and then we see that growth of algae and as that algae dies bacteria feed on that, depleting the oxygen.  We call this process eutrophication.  So it becomes very important to keep phosphorus on the land.  Ways we can do that of course is applying it according to soil tests so that we’re not applying it where it’s really not needed.  And then keeping the soil on the land through a variety of conservation practices.  Probably the easiest one for a farmer is to use some form of conservation tillage. So leaving crop residue to protect the surface, so you’ll get reduced dispersion from raindrops and runoff – that’s a great practice.  Other practices include crop rotation, contour cropping on hillsides.  Use of buffers or grass strips to reduce runoff across the field.

Sevie Kenyon

Dick, how about the homeowner and small property owner

Dick Wolkowski

Well what we find in a lot of our lawn and garden situations is that those gardens or lawns have received plenty of phosphorus over the years. So with a soil test, you can demonstrate that probably phosphorus is not needed.  In fact, there currently are laws that prohibit the use of phosphorus containing fertilizers on lawns unless it has been shown by soil test that they do require phosphorus fertilization.

Sevie Kenyon

We’ve been visiting today with Dick Wolkowski, department of Soil Science, University of Wisconsin Extension and the college of Agricultural and Life Sciences, Madison Wisconsin.  I am Sevie Kenyon.