Impact of machinery traffic on alfalfa production in dairy systems: An analysis of tire pressure and traffic patterns

Authors: Diaz Vallejo, Emily; Patel, Priyanka; ARRIAGA, FRANCISCO - University Of Wisconsin; Duff, Alison; JIAHAO, FAN - University Of Wisconsin; LUCK, BRIAN - University Of Wisconsin; QIAO, LANG - University Of Wisconsin; ZHANG, ZHOU - University Of Wisconsin; FRANCO JR, JOSE - Former ARS Employee

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2025
Publication Date: 2/19/2026
Citation: Diaz Vallejo, E.J., Patel, P.N., Arriaga, F.J., Duff, A., Jiahao, F., Luck, B.D., Qiao, L., Zhang, Z., Franco Jr, J.G. 2026. Impact of machinery traffic on alfalfa production in dairy systems: An analysis of tire pressure and traffic patterns. Agronomy Journal. https://doi.org/10.1002/agj2.70285.
DOI: https://doi.org/10.1002/agj2.70285

Interpretive Summary: Alfalfa is a key crop for U.S. agriculture, particularly for dairy and livestock, because it provides high-quality feed and environmental benefits. However, frequent use of heavy machinery during harvests can compact the soil or damage the regrowing of the alfalfa, reducing crop yield, forage quality, and overall soil health. Finding a balance between maximizing production and minimizing soil damage is crucial for sustainable alfalfa farming. Our study looked at how different harvesting strategies affect alfalfa yield and quality, and soil compaction. We conducted experiments at two sites in Wisconsin to see if controlled traffic farming, adjusting tire pressure, and choosing between silage and hay harvest methods could lessen the impact of machinery on the soil and improve crop productivity. The results showed that areas with no machinery traffic produced more yield than areas with direct traffic. Adjusting tire inflation pressure resulted in low and medium pressures reducing yield, while high pressure did not, but it improved protein content in one year. Soil compaction was higher in areas impacted by traffic, especially at shallow soil depths, and silage harvesting caused more compaction than hay harvesting. These findings reveal the complex relationships between machinery use, crop yield, forage quality, and soil health. Farmers should consider the importance of balancing immediate crop needs with soil conservation, particularly in dairy farming, where both high-quality forage and healthy soil are critical for long-term success.

Technical Abstract: Alfalfa (Medicago sativa L.) is an important forage crop in U.S. agriculture, supporting dairy and livestock systems due to its high nutritional value and environmental benefits. However, frequent machinery traffic during harvests can cause soil compaction and damage the regrowing plants, which negatively impacts crop yield, forage quality, and long-term soil health. Managing between minimizing compaction and timing harvests to achieve high forage quality and yield is critical for sustainable alfalfa production. The aim of our study was to evaluate the effects of controlled traffic farming (CTF), varying tire inflation pressures, and forage harvest management types (silage vs. hay) on alfalfa yield and quality, and soil compaction. Field and plot experiments were conducted at two sites in Wisconsin to assess whether these management strategies could mitigate the negative effects of traffic and improve forage productivity and soil structure. Results showed there was a negative correlation between alfalfa yield and intensity of machinery traffic in the field. Tire inflation pressure had a significant impact with low and medium pressures reducing yield, while high pressure did not, though it improved crude protein levels in one year, revealing a trade-off between yield and quality. Compaction was significantly higher in areas with direct traffic impact, particularly at 0–10 cm and 10–20 cm depths, and silage harvest management generally resulted in greater soil compaction than hay management. Our findings highlight the complex interactions between machinery traffic, alfalfa yield and quality, and soil structure. While CTF and tire inflation pressure adjustments did not produce immediate improvements in all areas, their potential to reduce long-term compaction remains important for sustainable alfalfa management. These insights underscore the need balance short-term productivity with soil conservation practices, especially in dairy systems where high-quality forage and soil health are both essential for long-term productivity.