Hemp plants were studied in Iran to see how different types of fertilizers affected their growth. They found that using a mix of cow manure and nitrogen fertilizer produced the most hemp biomass, seeds, and leaf extract. Nitrogen helped increase the oil content in the seeds, while phosphorus boosted the overall plant growth and seed and leaf extracts. The study suggests that hemp responds well to a combination of nitrogen fertilizer and animal manure, but doesn't benefit as much from phosphorus fertilizer.