Carrington Research Extension Center
North Dakota State University
NDSU Extension Service
North Dakota Agricultural Experiment Station

Ag Alert

April 21, 1999

As the age of an alfalfa stand increases, its yield potential decreases. Irrigated and dryland alfalfa studies conducted in North Dakota indicate that two- or three-year stands may be the age limit to maintain adequate yield. Average yield of eight irrigated trials at the Carrington Research Extension Center classified by age included 5.6 tons dry matter (DM)/acre for the first production year (year following establishment), 4.8 tons DM/acre for second production year, and 3.7 tons DM for third production year. Dryland yield of Carrington Center trials averaged 4.4 tons DM/acre for year one, 2.4 tons DM for year two, and 1.5 tons DM/acre for year three. Yield of three-year stands was about a one-third less under irrigation and about two-thirds less under dryland compared to first-year stands. The decline in yield with increased age may be due to accumulating winter injury and disease. The cost of reestablishing alfalfa stands after two or three years of production should be less than the yield loss with keeping older stands in production.

It is extremely important to insure that adequate amounts of sulfur (S) are present in the soil to optimize canola seed yield. NDSU's recommendation for canola is to apply 20 to 30 pounds per acre of S if a soil test indicates medium or lower levels. If S levels are high, apply 10 to 15 pounds per acre of S. An application of S is recommended even if a soil test indicates a high level because of field variability and soil tests tend to overestimate available sulfate-S levels. The sulfate form of S is readily available for plant uptake and use. Use a sulfate formulation of S such as ammonium sulfate
(21-0-0-24S). Elemental S is not recommended for sole use or as a blend due to its slow breakdown to sulfate-S. Canola S source trials conducted by NDSU in 1998 at Carrington, Langdon, and Minot averaged 1555 pounds per acre with ammonium sulfate as the S source compared to yield of 1260 pounds per acre with elemental S. Details on fertility recommendations for canola are available in circular SF-1122, 'Fertilizing mustard and canola', which is available at NDSU Extension Service offices.

Greg Endres, Area Extension Specialist/Cropping Systems, Email:
1998 Ag Alert Archive * Carrington R&E Center Home Page * NDSU Agriculture

Greg Endres, Area Extension Specialist/Cropping Systems, Email:
1999 Ag Alert Archive * Carrington R&E Center Home Page * NDSU Agriculture