Impact of machinery traffic on alfalfa in dairy systems: Tire pressure and traffic patterns effects

Alfalfa ( Medicago sativa L.) is an important forage crop in US agriculture, especially for dairy and livestock, due to its high nutritional value and environmental benefits. However, frequent machinery traffic during harvests can lead to soil compaction and damage to regrowing plants, adversely affecting yield, forage quality, and soil health. Our study evaluated the effects of controlled traffic farming (CTF), varying tire inflation pressures, and different forage harvest methods (silage vs. hay) on alfalfa yield and quality, and soil compaction. Field and plot experiments were conducted at two Wisconsin sites. Our results indicated a negative correlation between alfalfa yield and machinery traffic intensity. Tire inflation pressure effects on yield were variable: low and medium pressures tended to reduce yield compared to no‐traffic controls, while high pressure showed no yield effect. Soil compaction was notably higher in areas with direct traffic, particularly at 0‐ to 10‐cm and 10‐ to 20‐cm depths, and silage harvest management generally resulted in greater soil compaction than hay management. These findings highlight the complex interactions between machinery traffic, alfalfa yield and quality, and soil structure. While CTF and tire pressure adjustments did not produce immediate improvements in all areas, their potential to reduce long‐term compaction is important for sustainable alfalfa management. This underscores the need to balance short‐term productivity with soil conservation practices, especially in dairy systems where high‐quality forage and soil health are essential for long‐term productivity.