Why Your Soil Needs Phosphorus


Sep 28, 2019

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You want your lawn to be lush and green, right? To accomplish that, you need to give it all the nutrients it needs to flourish.

If you fertilize your lawn at all, you’ve probably heard about or seen vital nutrients like nitrogen, phosphorus and potassium (NPK) listed on the product labeling. The next thing you hear is that phosphorus can be hazardous to the environment. It’s causing lakes and ponds to become overgrown with algae.

So what’s the truth? Does your lawn really need it?

The answer is yes, phosphorus is absolutely essential to healthy turf.

The key is to apply it appropriately so that you have the lush, green lawn that you love without sending excess phosphorus into the environment.

What is Phosphorus?

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As mentioned, phosphorus is a nutrient that is an important part of the grass life cycle. It helps the plant do everything from establishing solid roots to storing and converting energy. It’s an essential part of photosynthesis.

Grass that is lacking in phosphorus will not grow properly and will likely be discolored as a result. The lawn may look especially dark with some grass appearing to be almost brown or black.

How to Tell If Your Soil Has Enough Phosphorus

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The only real way to know if your lawn is phosphorus deficient is to test the soil.

You can find do-it-yourself kits at many lawn care shops or box stores, but if you really want to get to the heart of what’s feeding your lawn, get a professional analysis of your soil. A professional analysis will let you know about your phosphorus levels as well as all of the other nutrients you need for a healthy lawn.

What is the Best Way to Add Phosphorus?

If you discover that your lawn is phosphorus-deficient, it’s time to give it a boost.

There are a few simple steps you can follow to help your lawn get back to where it needs to be without sending excess phosphorus into your local waterways.

Pick the right fertilizer

Most quality lawn fertilizers will include phosphorus.

In fact, when you see that 3-part number on your fertilizer those three numbers represent nitrogen, phosphorus, and potassium. They should always be in that order. For example, a bag of fertilizer labeled 18-4-12, will have a guaranteed by weight 18% nitrogen, 4% phosphorus, and 12% for potassium.

Your soil analysis should tell you where your soil is strong and what it’s lacking. Choose a fertilizer that will address your soil’s particular needs.

Apply the Fertilizer Properly

Misapplication of fertilizer is one of the biggest reasons that phosphorus and other chemicals run off of lawns and end up in other water supplies. Follow the directions on your fertilizer container carefully.

Time It Right

The best time to apply phosphorus fertilizer is fol­lowing aeration of turf in spring or early fall. Aeration is often necessary in compacted or poorly drained soils.

Star Tip: Fertilizers that are rich in phosphorus are often applied just before or directly after overseeding for an added boost in healthy root development and growth.

Keep It on the Grass

If you get some fertilizer on areas other than the grass such as a sidewalk or driveway,
clean it up right away. Fertilizer on hard surfaces is easily washed away.

Give Water Some Room

If your lawn borders a pond or a lake, keep your fertilizer five to ten feet away from the water’s edge. You want to be extra careful of any runoff that might occur as you do not want to pollute the water.

That section of the lawn should still benefit from the fertilizer being absorbed into the soil nearby.

Go Natural

If you don’t like the idea of spreading chemical fertilizer on your lawn, there are several natural methods to up the phosphorus in your soil.

Compost, manure and bone meal can all help increase the phosphorus for your lawn.

Introducing some clay particles can also help your lawn boost its phosphorus levels and keep them where you want them to be.

Just like you need your vitamins and minerals, so does your lawn.

Phosphorus is just one of the nutrients your grass needs to grow efficiently and to establish strong roots.

Test your soil every few years and then make conscientious choices to keep your lawn happy and your environment safe.