How to Add Phosphorus to Soil

PDF download Download Article
PDF download Download Article

Are your plants looking a little lackluster, or not growing as quickly as they should be? If so, your soil could be lacking phosphorus. This important nutrient is essential to any crop you’ll grow, and fortunately, there are ways you can add it to your soil using natural and organic products. In this article, we’ll tell you exactly how to add phosphorus to your soil, as well as when to add it and how to know if your soil needs it.

Things You Should Know

  • Use compost , animal manure , bone meal , rock phosphate , or green manure for natural sources of phosphorus.
  • Add it to your soil 1-2 weeks before you plant for best results. You can also add it during the growing season to give your plants a little extra oomph.
  • Check for stunted plant growth or a dark green coloring on your plants to determine if you need to add phosphorus. You can also use a soil test kit .
Section 1 of 4:

Natural Sources of Phosphorus

PDF download Download Article
  1. Compost is a natural fertilizer that releases phosphorus, nitrogen, and potassium over time. You can make your own compost out of kitchen scraps at home, or you can buy pre-made compost for your garden. [1]
    • To add compost to your soil, sprinkle 1 to 2 in (2.5 to 5.1 cm) of compost over bare soil and use a rake or a shovel to mix it with the top 3 to 5 in (7.6 to 12.7 cm) of dirt.
  2. Animal manure provides phosphorus, nitrogen, and potassium to your soil. [2] Simply buy a bag of animal manure and sprinkle 1 to 2 in (2.5 to 5.1 cm) over your garden. Mix it with the top 6 to 8 in (15 to 20 cm) of soil to provide nutrients over time.
    • It’s best to buy pre-made manure that’s been tested. That way, you know exactly how much of each nutrient is in the manure before you use it.
    Advertisement
  3. Bone meal is made from steamed animal bones, and it adds both phosphorus and calcium to your soil. [3] To add bone meal to your soil, measure out about 3 cups (384 g) per 100 square feet of soil. Sprinkle the bone meal over the dirt, then mix it into the top 1 to 2 in (2.5 to 5.1 cm) of soil.
  4. Rock phosphate is a sedimentary rock that contains phosphate and almost nothing else. If you’re sure that your soil only needs phosphate (and not nitrogen, potassium, or calcium), buy a bag of ground rock phosphate and sprinkle a 1 to 2 in (2.5 to 5.1 cm) thick layer over your soil. Use a rake or a shovel to mix it with the top layer of dirt. [4]
  5. “Green manure” describes the process of planting crops that are high in phosphorus, then plowing them back into the soil. If you’d like to add phosphorus over a long period of time, plant crops like oat, faba bean, clover, buckwheat, or mustard, and harvest them like you normally would. At the end of the season, till the plant matter back into the soil. [5]
    6. Advertisement
Section 2 of 4:

When to Add Phosphorus to Soil

PDF download Download Article
  1. Phosphorus usually takes a couple of weeks to be released into the soil. You can use phosphorus at any point in the season, but give your soil a few weeks to absorb it before you start planting. [6]
  2. If you’ve already planted your crops and you’ve noticed them looking a little blah, you can absolutely add phosphorus to the soil around your plants. Simply sprinkle your phosphorous product, like compost, around the plants, and carefully mix it with the top layer of dirt without disturbing the roots of your crops. [7]
    3. Advertisement
Section 3 of 4:

Why is phosphorus important?

PDF download Download Article
  1. The main thing that plants use phosphorus for is protein synthesis. Without phosphorus, your plants won’t have enough energy or nutrients to create new growth, which can slow or even stop the growing process entirely. [8]
Section 4 of 4:

How do I know if my plants need more phosphorus?

PDF download Download Article
  1. Plants low in phosphorus won’t grow as quickly as they should. If you’re halfway through the growing season and your plants aren’t as large or tall as you’d expect them to be, there’s a good chance that your soil is low in phosphorus. [9]
  2. Plants that aren’t getting enough phosphorus usually have a dark green color on the stems or the leaves. This color will look abnormal and unlike what you’re used to seeing on your plants. [10]
  3. The best way to tell what your soil is lacking is to use a soil test kit . The test kit will tell you the pH of the soil, as well as what nutrients are there and how much of them there are. Do a soil test kit before the growing season to see what your crops need.
    • In general, the optimal range of phosphorus in a vegetable garden is 30 to 50 parts per million (ppm). [11]
    4. Advertisement

Expert Q&A

Ask a Question
200 characters left
Include your email address to get a message when this question is answered.
Submit
      Advertisement

      Tips

      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Submit
      Thanks for submitting a tip for review!

      You Might Also Like

      How to
      Increase, Decrease, & Measure Soil pH Levels
      How to
      Make Homemade pH Paper Test Strips
      How to
      Add Potassium to an Organic Garden
      How to
      Break Down Clay Soil Fast
      How to
      Test Soil pH
      Why Does Your Soil Smell Like Ammonia? How to Fix Smelly Soil
      How to
      Acidify Soil
      How to
      Measure Soil Moisture
      How to
      Reduce Salinity in Soil
      How to
      Do a Home Soil Test
      How to
      Fix Compacted Soil
      How to
      Turn Clay Into Growing Soil
      How to
      Take an Accurate Soil Sample
      The Best Soil for Raised Garden Beds: A Complete Guide
      Advertisement

      Expert Interview

      Thanks for reading our article! If you’d like to learn more about soil enrichment, check out our in-depth interview with Ben Barkan .

      References

      1. ↑ https://ag.umass.edu/vegetable/fact-sheets/compost-use-soil-fertility
      2. ↑ https://extension.unh.edu/resource/guidelines-using-animal-manures-and-manure-based-composts-garden-fact-sheet
      3. ↑ https://s3.wp.wsu.edu/uploads/sites/403/2015/03/bonemeal.pdf
      4. ↑ https://extension.umn.edu/phosphorus-and-potassium/understanding-phosphorus-fertilizers
      5. ↑ https://cdn.dal.ca/content/dam/dalhousie/pdf/faculty/agriculture/oacc/en/technical-bulletins/2006/OACC_Technical_Bulletin_2006_17_web.pdf
      6. ↑ https://www.globalnetacademy.edu.au/grow-better-root-vegetables-by-adding-phosphorus-to-your-soil/
      7. ↑ https://www.hortmag.com/smart-gardening/compost-improves-the-garden
      8. ↑ https://passel2.unl.edu/view/lesson/0718261a1c9d/2
      9. ↑ https://passel2.unl.edu/view/lesson/0718261a1c9d/2
      1. ↑ https://passel2.unl.edu/view/lesson/0718261a1c9d/2
      2. ↑ https://extension.unh.edu/resource/guidelines-using-animal-manures-and-manure-based-composts-garden-fact-sheet

      About This Article

      In other languages
      Thanks to all authors for creating a page that has been read 33,019 times.
      If you buy through links on our site, we may earn a commission .

      Did this article help you?

      Advertisement