Add Lime to Low pH Soils this Fall for Alfalfa

Add Lime to Low pH Soils this Fall for Alfalfa

September 7, 2007

Do you have problems establishing alfalfa? The solution may lie in your soil's low pH level.

Alfalfa grows best in soils with a neutral pH of about 7. When soils are acid, with a pH of 6.2 or lower, alfalfa plants do not grow as well. At a low pH, alfalfa roots are less able to absorb nutrients from soil. And, the nodules on alfalfa roots that convert nitrogen from the air into nitrogen the plants can use have difficulty forming and working effectively in acid soils.

Most sandy, low organic matter soils as well as heavier ground that has been tilled and fertilized with nitrogen for many years have become acid. These soils need lime; however some folks still resist liming even when the soil pH is down to 5.5 or even below 5.

It takes some time for lime to really neutralize much acidity. So I recommend applying lime at least four months ahead of planting alfalfa. If you expect to seed a new field of alfalfa next spring, add lime if needed this fall to give it time to work. Sure it costs money, but it's much less costly then having a stand failure or several years of low alfalfa yields.

Bruce Anderson
Extension Forage Specialist