Plant Nutrient Values of Distillers By-Products.

Utilization of corn grain as a feedstock for ethanol fuel production has resulted in production of over 40 million metric tons of dried distillers grains in 2014 to 2015.  Most of these by-products are domestically utilized as livestock feed or internationally exported.  However, a shortage of rail car availability for by-product movement to markets has resulted in stockpiling of these materials at or near the production plants.  In 2014, a growing interest by production plants and grower groups in alternate uses for the by-products resulted in an initiation of a small study to evaluate the plant nutrient content of various by-products for use as a fertilizer substitute.  Special interest was taken in liquid materials (“syrup”) that have minor economic value.  Dry and wet distillers grains (DDG's and WDG's) as well as “syrup” were evaluated for moisture content and N, P, K, Ca, Mg, S, Fe, Zn, Mn and Cu contents over time to determine their variability over time as corn feed stocks change.  Weekly samples were collected from three ethanol plants in southeastern North Dakota and western Minnesota for 8 weeks and followed up with monthly samples for an additional four months. The N, P, and K values were similar to values found in the few examples in the literature.  Dry distiller's grains averaged 3.81, 0.73, 1.07, and 0.86 % N, P, K, and S, respectively, in an "as is" condition.  Wet distiller's grains averaged 1.91, 0.79, 1.12, and 0.85 % N, P, K, and S, respectively, in and "as is" condition.  Finally, the "syrup" material averaged 1.01, 1.51, 2.32, and 1.51 % N, P, K, and S, respectively, in an "as is" condition. Contents of other plant nutrients in the materials will be discussed.