Integrating poultry may result in greater plant-available nitrogen, phosphorus (P), and potassium (K)

• At the end of the three-year trial, plant-available nitrogen (nitrate and ammonium) was significantly higher for both poultry treatments than for the no-poultry Control.
• Soil P increased across all treatments during the three-year trial, but these increases were significantly larger for the two poultry treatments (68% for Treatment 2 and 73% for Treatment 3) than for the no-poultry Control (38%).
• Soil K increased across both poultry treatments during the three-year trial (34% for Treatment 2 and 49% for Treatment 3) but decreased for the no-poultry Control (-4%).

Integrating poultry may enhance water filtration, but may have lesser impacts on soil bulk density, aggregate stability, soil pH, and soil organic matter

• Water filtration (measured as hydraulic conductivity, in cm/h) was approximately 250% and 500% greater for Treatments 2 and 3, respectively, than for the non-poultry Control.
• No significant differences in soil bulk density, aggregate stability, soil organic matter (SOM), cation-exchange capacity (CEC), or soil pH were observed between treatment groups or growing seasons. These findings might be due in part to the short duration of the study; as such, longer-term studies are needed to understand the full impacts of poultry integration on soil physical properties.

Integrating poultry may enhance certain vegetable crop yields

• Significantly higher leaf lettuce yields were observed for Treatments 2 (96%) and 3 (86%) than for the non-poultry Control. However, no significant yield differences were observed between treatments for the broccoli growing season, suggesting that poultry manure impacts vegetable crop performance differently by crop type.

Integrating poultry after a summer cover crop rotation may provide additional soil health benefits

• Earthworm abundance was significantly higher for Treatment 3 than for the no-poultry Control. There were no significant differences in earthworm abundance between Treatment 2 and the Control, suggesting that the summer cover crop x poultry combination may provide suitable conditions for an earthworm-conducive environment.
• The summer cover crops in Treatment 3 utilized some of the nutrients available post-vegetable harvest but did not impact the growth of subsequent winter cover crops and vegetables. This suggests that a summer cover crop rotation may present an opportunity for farmers to mitigate excess nutrient runoff and water contamination without compromising future vegetable yields.