US HB3783

Amends the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) to establish a federal definition for "plant biostimulant" as substances or microorganisms that support plant natural processes to improve nutrient efficiency, stress tolerance, and growth

Excludes plant biostimulants from EPA regulation as "plant regulators" or "pesticides," including both biologically-derived products and synthetically-derived compounds that are structurally similar to biological substances

Requires the EPA Administrator to revise regulations within 120 days of enactment to implement the new definitions

Directs the Secretary of Agriculture to conduct a study assessing plant biostimulant types and practices that best achieve soil health goals, including increasing organic matter, reducing nutrient runoff, aiding carbon sequestration, and improving agricultural sustainability

Requires USDA to submit a report on study results to House and Senate agriculture committees within 2 years of receiving funding