Several aspects of a nutrient plan will need to be adjusted to account for dietary inclusion rates of distillers grains in beef cattle diets. Failure to consider these changes in a nutrient plan may produce a plan incapable of achieving the intended environmental goals or regulations. As DGS inclusion rates increase, your long-term or strategic nutrient plan should address:
Greater land requirements. At a 40% distillers grains with soluble (DGS) inclusion on a dry matter basis, P excretion will increase by approximately 90% as compared to a standard corn-based ration. This could require up to 90% greater land for manure application. N excretion also increases (about 50% for 40% DGS inclusion in diet), but most additional N is likely lost as ammonia for cattle housed in open lots.
Greater travel distances and time requirements for manure distribution impacting labor and equipment needs as well as capital and operating costs.
Management practices for minimizing soil erosion and runoff for fields receiving higher P content manures. Land treatment components of a nutrient plan should be reviewed and possibly revised. In addition, the annual nutrient plan (application rates, fields, timing, application methods) will commonly need adjustment as DGS inclusion increases.
Some of the key considerations include:
Book values of nutrient concentration will not be representative. In addition, past manure samples may not be representative of manure if DGS use has increased. New, farm-specific manure samples will be needed.
Application rates may need to be re-calculated when DGS is first included in the diet.
- If manure is applied at an N-based rate, field selection for manure application may need to be reconsidered. Some fields with a higher P index score may need to transition to a P-based rate immediately. The transition time for most fields to a P rate will also be shorter due to higher P applications resulting from N-based rates.
Additional information on the impact of using distillers grains and the impact on nutrient planning can be found at the Heartland Animal Manure Management website after May 1, 2008.
Author: Rick Koelsch, University of Nebraska