The profit margin of an NPK blending fertilizer produciton lines is greatly affected by factors such as production scale, cost control, and product positioning. The overall net profit margin of the industry is approximately 8%-15%, with large-scale projects reaching 15%-20%, while small-scale projects are mostly around 5%-10%.

Looking at the profit per ton, the current market price of NPK blended fertilizer is typically 2800-3500 yuan per ton, while raw material costs account for 70%-80% of the total cost, approximately 2200-2800 yuan per ton. Energy and labor costs per ton total 150-250 yuan, and equipment depreciation and management expenses amount to 80-150 yuan. Overall, the net profit per ton is generally 200-400 yuan, and can reach 400-500 yuan per ton with large-scale production.

Production scale has a significant impact on profits. A medium-sized project with a daily capacity of 100 tons has an annual capacity of approximately 30,000 tons. If the net profit per ton is 300 yuan, the annual net profit would be around 9 million yuan. A large-scale project with a daily capacity of 300 tons has an annual capacity of approximately 90,000 tons. Assuming a net profit per ton of 450 yuan, the annual net profit could exceed 40 million yuan, and the investment payback period could be shortened to about 3 years. Small-scale lines with a daily capacity of less than 50 tons, however, are affected by cost amortization, resulting in a net profit per ton of only 200-300 yuan, and relatively limited annual profits.

Product premiums and cost optimization can further expand profit margins. For example, specialized formula fertilizers and slow-release blended fertilizers for cash crops can have a 10%-15% higher selling price than ordinary products, and the net profit margin will be 3-5 percentage points higher. In addition, PLC-controlled automated production lines can reduce labor costs by 30%, and energy-saving NPK blending machine can save 50-80 yuan in energy costs per ton. Controlling raw material loss to within 2% can also reduce cost waste and further increase profits.