Factors influencing ammonia concentrations above corn fields after dairy manure application

Authors: Sherman, Jessica; Young, Eric; JOKELA, WILLIAM - Retired ARS Employee

Submitted to: Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2023
Publication Date: 8/8/2023
Citation: Sherman, J.F., Young, E.O., Jokela, W.E. 2023. Factors influencing ammonia concentrations above corn fields after dairy manure application. Environments. 10(8):140. https://doi.org/10.3390/environments10080140.
DOI: https://doi.org/10.3390/environments10080140

Interpretive Summary: Dairy farms rely on manure application to meet annual crop nutrient needs. Much of the nitrogen in liquid dairy manure is present as ammoniacal nitrogen and easily lost to the atmosphere if not incorporated into the soil. Conventional tillage implements like chisel plowing (CP) and low-disturbance manure application methods (injection or banding with aeration) can reduce ammonia losses compared to surface application. Vertical tillage (VT) is designed to reduce soil disturbance and maintain more crop residue compared to CP, however few studies have evaluated its ability reduce ammonia concentrations after liquid manure application. Six trials were performed in corn fields at the Marshfield Agricultural Research Station in Stratford, Wisconsin during 2013 to 2016 to evaluate the effectiveness of CP and VT on ammonia-N concentrations compared to surface applied manure and no manure controls. Results showed that ammonia concentrations for CP and VT were significantly lower compared to surface application. For the 0 to 24 hr period, CP and VT had similar ammonia concentrations with more variable results for the 24 to 48 hr post-manure application period. More crop residue remained on the surface with VT (39%) compared to CP (22%) when averaged across trials. Our results indicate that using VT after liquid manure application to corn fields significantly reduced ammonia concentrations compared to surface application while maintaining higher crop residue coverage than CP.

Technical Abstract: Ammonia-nitrogen loss from agriculture decreases crop yield potential and environmental quality. Incorporating animal manures by chisel plowing (CP) can reduce ammonia loss but may reduce crop residue remaining compared to lower disturbance incorporation methods and vertical tillage (VT). Few studies have evaluated VT efficacy for incorporating manure and reducing ammonia concentrations compared to CP. Six trials during 2013 to 2016 were conducted to evaluate impacts of manure incorporation method (CP, VT, or broadcast) on ammonia-nitrogen concentrations at a dairy research farm in central Wisconsin, USA. Passive samplers measured ammonia (30-cm above the ground) at 0 to 24 and 24 to 48 h post-manure application/incorporation. Average ammonia-nitrogen concentrations for CP and VT were 44 to 86% of broadcast and similar for most trials, while crop residue coverage for VT was greater than CP (39 and 22% of control plots, respectively). Concentrations of ammonia-nitrogen were correlated with the amount of plot area covered by manure for the first (r = 0.56, p < 0.0001) and second measurement periods (r = 0.85, p < 0.0001). Results show that VT had comparable ammonia-nitrogen concentration reductions to CP while conserving more crop residue.