LATE FALL IRRIGATION OF ALFALFA

by Bruce Anderson, Extension Forage Agronomist, Univeristy of Nebraska

               

                 Attention irrigators! Don't shut off your system for the season just yet.  Your alfalfa still might benefit from a little more water.  

                This drought has me a little worried for alfalfa.  We need some surface soil moisture to prevent alfalfa roots from drying out and dying over winter.  Soil moisture also helps keep soil temperatures from dropping too low for alfalfa plants to survive.

               

We also need water in our subsoil for top yields next year.  During the peak water use period in summer it can be impossible to keep up with the water demand of alfalfa with irrigation alone unless a water reserve is available in the deeper portion of the root and soil profile.  Irrigating now in October and into November until soils freeze thus can protect plants and improve yields.

                One advantage to irrigating now is low evaporation compared to summer, permitting very high irrigation efficiency.  Another advantage is the alfalfa plant itself.  Most irrigated fields of alfalfa never get much water below 4 feet deep.  But alfalfa can develop roots down 8 feet or more.  You waste some of the water collection ability of alfalfa by not building water reserves below 4 feet.

                Don't waste this ability.  That water reserve will keep your alfalfa growing rapidly during next summer's heat and allow you to irrigate on a more timely basis.  Plus, you won't need to worry much about winter survival or getting water immediately on your alfalfa after each harvest because you'll have a deep water reserve.  Since many alfalfa soils have low water infiltration rates, irrigating now might be the only time you actually can build that water reserve.

                So don’t turn off your systems just yet.  Irrigate alfalfa today for both winter survival and more alfalfa next year.