Recycling and management of manure in forage crops

Authors: Young, Eric; Sherman, Jessica

Submitted to: Western Alfalfa & Forage Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/11/2021
Publication Date: 11/18/2021
Citation: Young, E.O., Sherman, J.F. 2021. Recycling and management of manure in forage crops. Western Alfalfa & Forage Symposium. November 16-18. Grand Sierra Resort, Reno, NV.

Interpretive Summary:

Technical Abstract: Modern dairy production relies on capturing nutrient and production efficiencies for the animal and cropping sides of the business to optimize profitability. Manure management is an increasingly important economic and environmental aspect of dairy production. While manure nutrient content/speciation and total solids content can vary widely among farms and over time for individual farms, manure is a critical source of crop nutrients and soil organic carbon (SOC), underpinning long-term soil quality/health. Managing a range of semi-solid and liquid manures is common on larger dairy farms. Technology for handling, transporting, and incorporating manure has quickly evolved and encompasses a large range of field application equipment and tillage combinations. While broadcast/surface application of manure is still common in hay crop and annual cropping systems, incorporating manure with some type of tillage captures more nitrogen and often reduces nutrient runoff risk. However, tillage itself can also be counterproductive in some situations, particularly in coarser-textured soils with low organic matter content, where greater water holding capacity and SOC are required for improved crop growth. Low disturbance manure application (LDMI) can incorporate manure (via injection or enhancing manure infiltration) while reducing soil disturbance compared to tillage incorporation (chisel, disk/harrow). Shallow disk injection and aeration-banding are two LDMI methods that use liquid manure and can be used during both corn and hay crop production. Research at the USDA-ARS indicates that shallow disk injection conserved more N for fall-applied manure in a corn-silage winter rye cover crop system and maintained more surface residue compared to tillage. Additional experiments also indicated a relatively low risk of yield reduction for shallow disk injection and aeration-banding application methods in hay crop and corn silage fields. LDMI methods therefore show promise for improving nutrient use efficiency and utilizing more on-farm nutrients, however longer-term research at multiple locations is needed to better evaluate possible impacts of LDMI on forage yield and quality.