How to Add Phosphorus to Soil for Healthy, Fast-Growing Plants Phosphorus is an essential soil nutrient plants need to thrive. Close Credit: Getty Images Phosphorus is a vital mineral for healthy plant growth. Unlike carbon dioxide or oxygen, which plants receive from the air, plants access phosphorus in the soil through their roots, a process aided by microbes in the soil. Plants use phosphorus during photosynthesis and for energy storage in the plant's adenosine triphosphate molecules. Without sufficient phosphorus in the soil, plants grow more slowly, are weaker, and don't produce their normal yield of flowers or fruits. Christine Froehlich, horticulturist and owner of Gardening With What You Have, where she offers landscape design services to home gardeners Meg Austin, gardening instructor and fifth-generation farmer You can conduct a soil test to determine if your soil is phosphorus-deficient. If the test results reveal that your soil lacks this essential mineral, consider some of the following methods experts say will boost the phosphorus in your soil. Most plants prefer a soil pH of 5.5 to 7.5. If it’s outside this range, it’s challenging for plants to absorb nutrients properly. "If it is too acidic, phosphorus will not be available to the plant," says horticulturist Christine Froehlich. Remember to look at the whole picture when amending your soil—don't look solely at phosphorus amounts in isolation. Use a Commercial Fertilizer Commercial fertilizers contain three essential nutrients for plants—nitrogen (N), phosphorus (P), and potassium (K). Every product has a ratio of each nutrient, commonly referred to as the NPK ratio. For example, a 10-10-10 fertilizer is 10 percent nitrogen, 10 percent phosphorus, and 10 percent potassium. If you tested your soil and found it is low in phosphorus, you might look for a fertilizer with a higher concentration of P—perhaps a 10-20-10 or similar. Apply Compost from Animal Manure Compost enriched with animal manure is one of the best natural ways to add phosphorus to your soil. According to our experts, chicken and cow manure are especially rich in this mineral. When sourcing animal manure from a farm (or your backyard chicken coop!), make sure it is composted first, or you risk adding too much nitrogen to your soil. Use Rock Phosphate At the end of its cycle, phosphorus ends up in rock form. These rocks can then be ground up and used as plant nutrients, starting the cycle over. Rock phosphate is a slow-release form of phosphorus that can be added to the soil to help amend it over time. Rock phosphate is available from retailers in bagged form. It has a powder-like consistency that is worked into the soil near the roots. Don't Miss How to Add Nitrogen to Soil to Revive Your Garden, According to Experts How to Make Fertilizer Using Common Household Ingredients—and Why You Should Fish Emulsion A faster way to add phosphorus to your soil is by amending it with fish emulsion. "I like to give my garden soil a fast boost of phosphorus with liquid fish emulsion—it’s easy to apply, and the plants love it," says gardening instructor Meg Austin. "I just mix it with water and pour it around the base of whatever needs the help." But she does warn that critters and pets may be attracted to the odor. "If you’ve got free-range farm dogs or wildlife nearby, you’ll want to think about fencing off the area or at least keeping an eye on it for a few days so your garden doesn’t get dug up," she says. Bone Meal Another way to slowly amend your soil is with bone meal, which is also rich in calcium. "Another way I add slow-release phosphorus is by sprinkling bone meal around my root crops and fruiting plants," says Austin. Bone meal is sold as a powder you can apply before planting or after plants are established. Explore more: Garden Vegetable Garden Ideas