How To Add Phosphorus To Soil

How To Add Phosphorus To Soil

Phosphorus and potassium are the primary nutrients that plants search for to remain healthy. However, it doesn’t mean you can add lots of this and get larger yields.

If the amounts are off, you can either have a nutrient deficiency in your plants, or it is too much, and it causes other issues.

In our guide, you can learn more about adding phosphorus to soil and how to add potassium to the soil in the right amounts.


By the end, you’ll better understand the benefits it brings to your gardening efforts. You will also see how to monitor levels to ensure you don’t have high phosphorus or your other nutrients are out of balance. (Read Does Potting Soil Go Bad)

What is a Good Source of Phosphorus for Plants?

Plants need three macronutrients for healthy growth. Mostly, they get these from the soil: nitrogen, phosphorus, and potassium. Each has a specific role in plant development, and you can add many substances, materials, and mixes to the soil to improve nutrient content.

You can use such things as commercial fertilizers containing phosphorus, such as rock phosphate or bone meal, or other materials like hair, shellfish waste, urine, and more.

What is important is to know the amount of plant-available phosphorus in the soil, which you can determine with a simple soil test. You will see if your soil is acid or alkaline and thus how to amend it.

Some phosphorus sources have a lengthy history, while others have only recently been created. Gardeners have many possibilities, yet phosphorus is a finite resource, and adding too much can harm plants and the environment.

You can never underestimate the importance of phosphorus in plants because of its reproduction function. It can boost crop yield, quality, and maturity crops while strengthening stalks and promoting root growth.

Unfortunately, phosphorus can be found in low quantities in agricultural soils as it is either used or leaches away. Most typical soils provide enough phosphorus to support growth. However, low phosphorus levels lead to stunted growth, smaller yields, and a slow maturation process.

Aside from phosphorus, the other two elements in fertilizers, nitrogen, and potassium, also play a function. Adding potassium to soil helps with photosynthesis and promoting seed and fruit development, and regulating metabolic activities.

Human and animal urine provides some macronutrients plants require to thrive. While it can be beneficial, farmers don’t use it to raise phosphorus in the soil in case of infections and pharmaceutical drug residues. (Find the Best Shrub Fertilizer)

Another thing to note is that urine contains a high level of nitrogen that leads to plant burns.

You can find easier methods and substances to use, such as a bone meal. Nutrient levels in bone meal can range from 15 to 27% phosphorus. (Find the Best Soil Testing Kit)

You will find this organic substance has many benefits and is used commercially along with manure. Manure or bone meal provides your crops phosphorus, nitrogen, and potassium.

Phosphate, a phosphorus-calcium compound, is widely mined, yet You shouldn’t use this phosphorus source in soils with a pH above 7. It offers some advantages, such as being less expensive than the bone meal and containing calcium, magnesium, and many other trace minerals and nutrients. It does, however, present some disadvantages.

plant in a hand

Too Much Phosphorus Is Too Much of a Good Thing

Too much phosphorus will harm plants and can harm the environment. High phosphorus levels hinder the growth of soil organisms such as mycorrhizal fungi.

You can find that adding phosphorus isn’t always necessary in every soil. Grass, for example, doesn’t produce large flowers or fruit; thus, phosphorus in the soil should be enough. Too much, and you can see burns on smaller plants such as grass.

For the environment, runoff from your garden to nearby water systems and this excess phosphorus can lead to algae blooms. This lowers oxygen content and then kills many living aquatic creatures. (Learn What To Do With Old Potting Soil)

How Do You Increase Phosphorus in Soil?

Here you can find various ways to raise phosphorus and potassium in soils for optimum plant growth.

Method 1: Bone Meal

  1. Conduct a soil test to determine phosphorus levels and potassium levels using a home test kit. You can determine if your soil is Slightly, moderately, or deficient in either or both nutrients. Once you know this, you can determine the amount of fertilizer to add to benefit your crop. Monitoring and correcting high phosphorus in the soil is vital for optimal plant crop growth in your garden.
  2. Remove weeds from the garden bed.
  3. Rake your garden bed until smooth.
  4. Scatter bone meal across the top of your garden bed to add phosphorus to the soil.
  5. For every 1,000 square feet, you need to apply 30 pounds for severely deficient soil, 20 pounds for moderately deficient soil, and 10 pounds if your soil is slightly deficient.
  6. You can ass kelp meal for potassium, and here you add 20 pounds for severely deficient, 10 pounds for moderately deficient, and 5 pounds for slightly deficient soils.
  7. After adding, till the two fertilizer solutions into the top 8 to 12 inches of soil.
  8. Water your garden thoroughly, so the nutrients and fertilizers are absorbed and increase soil fertility.

Method 2: Rock Phosphate

  1. Use steps 1, 2, and 3 above to test and prepare your garden bed.
  2. Scatter rock phosphate on your garden bed to add phosphorus.
  3. For every 1,000 square feet, apply 60 pounds for severely, 25 for moderate, and 10 for slightly deficient soils.
  4. You can use granite meal or greensand to add potassium. The amounts are the same, whichever amendment you use. For every 1,000 square feet, use 100 pounds for severe, 50 for moderate, and 25 for slightly deficient soils.
  5. The soil amendments into the top 8 to 12 inches of the soil surface to correct the deficiency.
  6. Water your garden to allow the nutrients to be absorbed from the garden bed.

If the mineral becomes water-soluble, it doesn’t offer slow-release, and it is here where it leaches into water systems faster.

If you have already planted your garden, you need to rake away any mulch or compost so you can spread the fertilizer around your plants and water the fertilizer into the soil’s surface.

A professional soil test tells you your garden’s current nitrogen, phosphorus, and potassium levels and whether the soil is noticeably lacking availability of any micronutrients. The recommendations can guide you to make your choices about amendments.

Organic compounds like granite and kelp meal offer high potassium levels and specific trace minerals. You can find granite meal high in silica, and also bone meal contains calcium and phosphorus that can make up for any deficiency for healthy crop production.

Dry fertilizers, even organic varieties, can irritate your skin and lungs. Whenever you feed your garden with these, you should pick a day that isn’t windy and wear a mask, along with long sleeves and gloves.

How do you increase phosphorus in soil naturally?

Phosphorous is among the 3 key nutrients for healthy plant growth. Here are ways you can raise phosphorus levels naturally.

  • Bone meal: A great source made from livestock bones in the food industry. They grind these up into a fine powder you can use around your garden for a rich source of phosphorous.
  • Rock phosphate: Slow-acting source and often used where soil converts rock phosphate into phosphorous where plants can eventually use it. Unfortunately, there is a limited supply globally.
  • Phosphorus Fertilizers: A fertilizer containing high phosphorous in the NPK ratio, such as a ratio of 10-20-10, where 20 is the phosphorous percentage.
  • Organic compost: You can add high-quality organic compost to your soil to increase phosphorus content.
  • Manure: Manure can be a substantial source of phosphorous for your plants and many other minerals and nutrients.
  • Clay Soil: Introducing clay particles to your soil helps retain and correct phosphorus deficiencies.

Maintaining a soil pH of 6.0 to 7.0 range has been proven to offer the optimal phosphorus uptake in plants.

coffee ground

Do coffee grounds contain phosphorus?

Coffee grounds contain around 2 percent nitrogen, 0.06 percent phosphorus, and 0.6 percent potassium. In addition, they contain many micronutrients such as calcium, magnesium, boron, copper, iron, and zinc.

Coffee grounds are useful for controlling soil temperatures and helping increase soil water retention.

Using the above, you can increase soil fertility, yet you need to know that adding too much won’t particularly add too many benefits and can harm your soil and plants. You better stick to organic rather than chemical fertilizers as these are more than adequate and better for the environment. (Learn How to Amend Clay Soil)

As you go on, you should regularly conduct a soil test to check your phosphorus levels as these can change before, during, and after the growing season.

Like any fertilizer, your plant crop can only absorb so much, and when the nutrient supply availability is too much, it can cause issues, or You will waste it. (Read Is Coffee Grounds Good For Tomato Plants)

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