This bill, titled the "Homegrown Fertilizer Act," directs the Secretary of Agriculture to establish a program providing grants and direct or guaranteed loans to eligible entities. The primary goal is to significantly increase or expand the manufacturing, processing, and storage of fertilizer and nutrient alternatives within the United States for the benefit of American farmers. Eligible entities include independently owned businesses, non-profit organizations, producer-owned cooperatives, Indian Tribes, and State or local governments, provided they are physically located in the U.S., comply with all regulations, and do not hold a market share equal to or greater than the fourth-largest in the fertilizer market. The Secretary is mandated to prioritize projects that will improve fertilizer production methods, dedicate additional capacity to U.S. agricultural commodity production, or demonstrate an ability to enhance competition and reduce price volatility for farmers. Funds can be used for a wide range of activities, including building new facilities, purchasing equipment, providing working capital, and developing workforce training programs. Grants are capped at $100,000,000 and require matching funds, while loans follow terms similar to existing USDA business and industry loans. A key condition requires repayment of the grant or loan if the funded company or facility is sold within 10 years to an entity exceeding the fourth-largest market share in the fertilizer industry.