How to Add Phosphorus to Soil

Phosphorus is one of three main ingredients in commercial fertilizers. The middle number in a fertilizer (example 15-20-15) represents the amount of phosphorus in the fertilizer.

Phosphorus is needed by plants to stimulate root growth, and to help plants set flowers and fruits.

However, too much phosphorus is worse than a deficiency. Phosphorus deficiencies occur more often in agricultural fields that are heavily farmed. Phosphorus deficiency is not as common in home gardens and urban landscapes.

Before adding phosphorus to your soil, it's extremely important to have your soil tested. This can be done for a reasonable cost at your county extension office. In addition, the lab will give you recommendations on how to improve your soil, including products and amounts.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• A source of phosphorus, such as bone meal, animal manure or rock phosphate
• Rototiller or garden fork
• Dry weather
• Soil test results

1. Choose what kind of application of phosphorus you will use. If you have a lab report from a soil test, the lab will make recommendations based on soil specifics in your area. The amount necessary truly depends on the state of your own soil, which can only be determined by a soil test.

2. Phosphorus is not very water soluble and takes time to break down enough for plants to utilize. Products containing rock phosphate take even longer, sometimes two to three years. Animal manures and bone meal are excellent sources of phosphorus, and are readily available.

3. If you plan to till your garden in either spring or fall, this is the best time to add any extras, including phosphorus. Using the rototiller, work the product into the soil.

4. Phosphorus can also be worked into the soil by hand, using a garden fork. Simply apply the recommended amount of product on top of the soil and dig fork into soil, turning the top soil under as you go.

5. Some products are designed to be broadcast on top of the soil for ease of use, and don't have to be worked in. If you choose this method, be sure to check the weather forecast and find a time when rain is not expected, to decrease the chance of runoff.

Tips & Warnings

• An overabundance of phosphorus can cause yellowing of leaves. Many gardeners incorrectly assume this yellowing is a nitrogen deficiency and add a large dose of all-purpose fertilizer, which will add even more phosphorus.
• A number of researchers believe that too much phosphorus in urban areas is more widespread than anyone knows and that it harms beneficial fungi, leading to plant distress.
• Excess phosphorus can leech into groundwater, causing an upset in the balance of algae and bacteria, which leads to the death of fish and other animals.
• Some towns and states have begun to regulate (and in some cases ban) the use of phosphorus in fertilizers due to runoff and the resulting problems.

[Willi]

on 3/20/2008 This is a great article. Thanks for suggesting that people get a soil test first. Phosphorus run off causes serious water quality issues in many areas of the country and your advice is spot on.

[only1special1]

on 3/17/2008 Nice job!

[SunflowerOcity]

on 11/30/2007 Well done
I enjoyed your article and rated it with five stars! Check out my fertilizer related articles at the following links.
http://www.ehow.com/how_2128658_use-foliar-fertilizers.html
http://www.ehow.com/how_2109524_understand-fertilizer.html
http://www.ehow.com/how_2109523_grow-great-plants-fish-fertilizer.html
Chris