When it comes to the growth of the plant, any gardener will think of the first nitrogen fertilizer. However, when it comes to legumes like Beans, these plants are nitrogen fixers. Therefore, they are capable of fixing nitrogen in the soil and this nitrogen is obtained from the air. So, avoid supplying your Green Beans with nitrogen-rich fertilizer as it can harm your plant. Excess nitrogen can result in the growth of extra stems and leaves and maybe offered little or small Beans.
Phosphorus is an essential nutrient for Bean plants need to develop a good root system to a large extent. But as we have mentioned before, Beans do not require heavy nutrients. Therefore, you can only use 3-inch layers of fertilizer to enhance the growth of your Green Bean plant. Potassium is another nutrient that can help Green Beans grow effectively. It is like a supportive nutrient in the growth of the Beans.
Source- Agriculture Website