Oklahoma State University Stillwater, OK
Oklahoma Alfalfa Oklahoma Cooperative Extension Service Oklahoma Agricultural Experiment Station

Working Old Alfalfa Fields for Renewed Vigor We are frequently asked what we think about working old alfalfa fields. Sometimes the question is worded using "plowing", sometimes "disking", sometimes "alfalfa harrow", and other terms, such as renovator.  Plowing to one person is deep tillage (at least a foot deep), to others plowing means pulling anything across a field that stirs up some soil.   With this different terminology from alfalfa producer to producer, sometimes in the same county, the question becomes difficult to answer.    Sometimes we hear claims of good weed control by working fields during winter. In other conversations, it is suggested that working the field is needed to improve water infiltration into soil. Sometimes producers just say it makes the alfalfa grow better, faster, and greener.   These claims are probably correct in a certain context. Let's take a somewhat different approach.   Occasionally shallow (1 to 2") winter tillage does improve water infiltration. This is probably fairly rare, especially after winters when temperatures fall to about zero without much snow cover. The contraction and expansion of soil during cooling and warming probably loosens the soil enough.   Very small weeds may be killed with light disking and/or dragging a spike-tooth harrow across alfalfa fields during the winter. Any type of deeper tillage that kills large weeds will also hurt alfalfa plants which is alright if you have plants to spare.   Phosphorus fertilizer and lime move very slowly through the soil. Shallow incorporation will help move them to the roots, but not much.   The claims that shallow tillage makes alfalfa grow faster, with more vigor, and greener may be true. The effect credited to the tillage could usually be the effect of getting into late winter or early spring and warmer weather. To check out this action, just skip strips through the field to see if there is a difference.   The main positive impact of dormant-season tillage is to smooth the field. This may be important. Fields should be smooth to make traffic next summer safer, and smooth fields look better and are nicer to work in.   So, if you want to "plow" your alfalfa during the winter, go ahead. It is probably a good cure for cabin fever and it costs less than going to Las Vegas or skiing.

John Caddel, Forage Agronomist  Department of Plant and Soil Sciences  Oklahoma State University

 

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