In this lesson on agriculture business, the focus is on fertilizers, particularly phosphorus fertilizers. Students learned about various types, including single superphosphate and monoammonium phosphate, as well as the importance of other nutrients like calcium, magnesium, and sulfur. The lesson highlighted that phosphorus fertilizers work differently from nitrogen fertilizers and should be used carefully in combination with primary nutrients to enhance soil quality. Additionally, the lesson touched on the role of inhibitors that can improve fertilizer efficiency and stabilize ammonium levels in the soil.