Several months ago, I received an inquiry about using PAM to treat irrigation water to reduce erosion, especially that induced by furrow irrigation.

When irrigation water is applied to soil, topsoil is gradually lost in irrigation runoff. Obviously, this loss will be greater on fields with greater slopes. Results from numerous studies have shown that PAM increases the resistance of soil on the surface to dislogdement and subsequent movement down the furrow that is caused by water flow, thus reducing soil loss during irrigation.

PAM is a flocculent that is widely used in municipal water treatment, paper manufacturing, and food processing. When applied to soil with irrigation, it binds to clay particles, which carry a negative charge. By increasing the cohesiveness of soil particles on the soil surface, PAM makes soil more resistant to the erosive forces of water flowing over it.

PAM preserves a more pervious pore structure during irrigation, and thus allows increased infiltration of irrigation water that is applied to the soil surface.

The majority of research with PAM use in irrigated crops has been conducted in the Midwest and Western US. There has been little if any research with PAM that is applied with irrigation on the loam and clay soils in the Midsouth.

Some general guidelines for PAM use are:

• PAM should be used at the first irrigation if the soil has been disturbed by cultivation or is loose from lack of rain.


• If soil is undisturbed following the first PAM application, following irrigation(s) can be applied with no or a reduced rate of PAM.


• Regardless of the form of PAM that is applied, it needs turbulence to dissolve in water. Even though dry forms require more turbulent mixing than liquid forms, all forms need to be added to incoming water at a turbulent point.


• PAM can be injected directly into sprinkler systems.


• PAM applied with irrigation water results in and maintains higher infiltration rates than is normal with untreated water. Thus, irrigation practices will have to be adjusted to prevent over-watering, especially on soils that have a high inherent infiltration rate.

For an article with a list of sources that contain details about PAM use, click here.

Composed by Larry G. Heatherly, July 2014, larryheatherly@bellsouth.net