Superphosphate facts for kids

Superphosphate is a special kind of fertiliser that helps plants grow big and strong. It was first made way back in the 1840s by mixing animal bones with a strong acid called sulfuric acid. Later, people found better ways to make it using fossilised animal waste (called coprolites) and other rocks rich in phosphate.

Plants need phosphate to be healthy, just like you need vitamins! Superphosphate made it much easier for farmers to grow more food, which changed farming forever.

How We Got Superphosphate

Before superphosphate, farmers used things like guano (bird or bat droppings), animal manure, or crushed bones to fertilise their crops. These things were so important during the time of the Industrial Revolution that people even dug up old graves and catacombs in Europe to get human bones for fertiliser!

Then, in 1842, a smart person named Reverend John Stevens Henslow found coprolites – which are actually fossilised dinosaur poop! – in the cliffs of England. He knew from earlier research that these coprolites had lots of phosphate. He also knew that if you mixed them with sulfuric acid, the phosphate would become easy for plants to use.

A farmer named John Bennet Lawes heard about these discoveries. He did his own experiments on his farm, which later became a famous agricultural research station called Rothamsted. He created a new product and called it "super phosphate of lime." In 1842, he got a patent for his discovery and started making superphosphate from dinosaur dung on a large scale. This was the very first chemical fertiliser ever made in the world!

Another businessman, Edward Packard, saw how important Lawes's discovery was. He turned a mill in Ipswich into a factory to make this new fertiliser using coprolites. His factory, along with another one started by Joseph Fisons, eventually became part of the big Fisons fertiliser company. There's even a street in Ipswich still called Coprolite Street today!

Why Superphosphate Helps Plants Grow

All living things, including plants and animals, need phosphorus to work properly. Even though plants only have a tiny bit of it, phosphorus is super important for their growth and energy.

Superphosphate is much cheaper than other ways to get phosphorus for plants. This low cost has made it very popular, especially in places where farmers need to keep their costs down.

When superphosphate is added to soil, a lot of its phosphate becomes available to plants right away. This gives plants a quick boost, helping them grow faster and stronger. However, over time, the phosphate can get stuck to other minerals in the soil, making it harder for plants to reach. Also, when farmers harvest their crops, some of the phosphorus is taken away from the soil.

Adding superphosphate helps farmers get much bigger harvests from their crops. While some phosphorus naturally returns to the soil, it's usually not enough for modern farming needs.

One challenge with superphosphate is that because it's so easy for plants to use, it can also easily wash away from fields into rivers and streams. This can cause problems like eutrophication, where too many nutrients lead to too much algae growth, harming fish and other water life.

How Superphosphate is Made Today

Superphosphate is made in many industrial places around the world, like Europe, China, and the US. In 2021, a lot of superphosphate was produced, with Poland, Indonesia, Bangladesh, China, and Japan being some of the biggest makers.

All types of superphosphate have a good amount of phosphate that plants can easily use. This is why they are so important for modern farming.

Single Superphosphate

This is the original type of superphosphate. It's made by mixing phosphate rock with sulfuric acid.

Triple Superphosphate

This type is a key ingredient in many different fertilisers. It's made by treating phosphate rock with a different acid called phosphoric acid. Triple superphosphate has a much higher concentration of phosphorus than single superphosphate, meaning you need less of it to get the same effect.

Challenges with Superphosphate Use

While superphosphate is very helpful, there are some things to watch out for:

• Soil Changes: Using superphosphate all the time can make the soil more acidic, especially in certain types of soil. This can change how well plants can get other nutrients. Farmers need to check their soil regularly to make sure it stays healthy.

• Environmental Impact: Making and moving superphosphate uses energy and can produce carbon dioxide, which contributes to climate change. However, some ways of making it can actually have a very low carbon footprint if the heat produced is reused.

• Plant Health: If too much superphosphate is used, or if it's not balanced with other nutrients, it can sometimes harm plants. There's also some evidence that high levels of phosphorus might be linked to certain plant diseases. Farmers use soil tests to figure out exactly how much fertiliser their crops need.

• Limited Resources: The rocks used to make superphosphate are limited. Experts aren't sure exactly when we might run out, but it could be in the next few decades. As the world's population grows and we need more food, finding new ways to get phosphate will become very important.

• Sensitive Plants: Some plants, especially those from places like Gondwanaland (an ancient supercontinent), are very sensitive to too much phosphorus. They get all the phosphorus they need from special fungi that live with their roots. Adding superphosphate can actually hurt these plants. Examples include Hakea prostrata and Grevillea crithmifolia. Many types of orchids might also be sensitive.

• Water Pollution: As mentioned before, phosphate from fertilisers can wash into rivers, lakes, and the sea. This can cause too much algae to grow, which uses up oxygen and harms fish and other aquatic life. While superphosphate contributes to this, other sources of phosphorus, like animal waste, also play a big role.