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What is a Superphosphate Fertilizer?

By Debra Durkee
Updated May 16, 2024
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Superphosphate fertilizers have a high content of the nutrient phosphate. One of the three nutrients essential to healthy plant growth, phosphate can be applied in a high concentration with a superphosphate fertilizer to plants ranging from houseplants to agricultural crops. Several different types of this fertilizer have been created for different needs.

The three different types of superphosphate fertilizers are distinguished by the amount of phosphate in them. Single superphosphate is the mildest grade, and contains between 16 and 20 percent phosphate. It is typically available in a liquid or a dry formula, both of which are used with the same efficiency by plants. It is also known as normal superphosphate fertilizer. Dicalcium superphosphate is the next grade, which contains anywhere from 35 to 38 percent phosphate, depending on the mix and brand.

The strongest version of superphosphate fertilizer is triple phosphate. Also known as concentrated superphosphate, it is typically combined with another type of fertilizer to be applied as a compound. Triple superphosphate is more frequently used in an agricultural setting or with commercial crops; there are several processes used to create this type of fertilizer, and in most cases it is available as a granular form. All three types of superphosphate are usually made with a naturally occurring substance called rock phosphate. While this can be applied as a fertilizer in its raw form, putting it through the chemical reactions to create other types of fertilizer has been found to make it more effective.

A superphosphate fertilizer is made with a process that involves creating a reaction between the raw phosphate rock and an appropriate percentage of sulfuric acid and water. The process that creates superphosphate fertilizers releases chemicals into the air, adding to air pollution and water pollution. Controlling these waste products means producing the fertilizer in a complicated process that must be overseen in order to ensure the least amount of waste product is released into the environment.

When applied to the soil, a superphosphate fertilizer raises the amount of phosphorus available to plants. Regardless of type of plant, all require a healthy amount of phosphorus in order to survive. This nutrient is present in every cell of the plant, and is vital in maintaining the strength of the cell structure. A high level of phosphorus also increases the rate of movement of water throughout the plant structure, makes leaves healthier, and helps the plant produce better and more viable seeds.

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Discussion Comments
By anon997179 — On Nov 26, 2016

What are the uses of single super phosphate fertilizer on soil?

By anon996888 — On Oct 22, 2016

JimmyT-- I learned a great deal from my father (now 87)- a master rosarian. He said (and always used) the regular super-phosphate throughout his vegetable garden and throughout his flower gardens. Especially in the fall he would apply "a handful" of the dry material and scratch it in around the base of each major flowering plant and would rake in an equal amount around other plantings.

In the spring, he recommends using it after young plantings get established. Then he would "side-dress" the row of plants or scatter a cup of the superphosphate along the side of the plants and rake it in. This superphosphate strengthens the canes or stems of the plants and supports the movement of nutrients & water through the plant.

By anon295925 — On Oct 09, 2012

My agricultural lands are in areas where there is a lot of water in the whole area. It is a water-rich area.

For the whole season, water is present in the land up to 2 feet high, which means up to half of the plants are covered in water. This is due to heavy rains and low-lying land. We produce rice only. What type of fertilizer should I use for my crop? Does anyone have any ideas about it?

By JimmyT — On Jul 15, 2011

I did a soil test in my garden at the beginning of the year and found that I need quite a bit of phosphorus. Enough so that I should probably use some type of superphosphate.

Does anyone here have any experience with using superphospate? What is the best fertilizer, especially for typical vegetable garden plants (tomatoes, peppers, cucumbers)? Also, is it easiest and most effective to use water soluble fertilizer or the solid type?

By Izzy78 — On Jul 14, 2011

What is the difference between rock phosphate and the processed fertilizers that make them so much different?

It seems like just putting on the rock phosphate would be much better, since it doesn't damage the environment. I'm almost positive that sulfuric acid is the main component of acid rain, and water pollution is always bad, too.

Wouldn't there be some other chemical besides sulfuric acid that could do the same job with less pollution?

By kentuckycat — On Jul 14, 2011

Although the article doesn't mention it, adding too much phosphate fertilizer can be very damaging to plants. There is a very specific level that plants need, and going over that limit will cause what is called phosphorus burn.

If your plants ever start to develop purple tinted leaves, it probably means that you have too much phosphorus in the soil. I figured this out the hard way with my tomato plants several years ago. I never knew that there was a limit on how much you should give to a plant. I believe there are also dangerous limits for the other major nutrients (nitrogen and potassium), as well.

By stl156 — On Jul 13, 2011

@jmc88 - Herb gardens are a great way to save on buying the pricey stuff at the store. Home grown herbs always taste much better than the dried stuff, too.

I've had a window box herb garden for quite a few years now. I'm not sure what type of soil you are using, but depending on the type, you may not need fertilizer for a while. I started the plants in potting soil that already had plenty of the necessary nutrients. They grew great for a couple of years until all of the nutrients started to get sucked up. After that, I put on a little of the Miracle Gro powder, and that helped them a lot.

Basically, if you used regular potting soil, you should be fine for a while, but if you notice the plants starting to shrink or get droopy, I'd give them a little dose of the Miracle Gro to help them out. In the case that you planted them in the ground outside, I might suggest ordering a soil test. That will give you a better idea of what you might need to add to the soil. Best of luck with your garden!

By jmc88 — On Jul 13, 2011

I just put together a small herb garden for my home. I haven't done a lot of gardening in the past, so I'm a little unsure about how to make the plants grow best. I definitely haven't done anything like an herb garden before.

Do I need to put any type of phosphorus fertilizer on my plants, or will they be fine without it? So far I've been using Miracle Gro. Will that be enough? It has always seemed to work for my other garden plants.

If I do need some other type of fertilizer, what should I look for, and how should I apply it?

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