Understanding phosphate may stop an environmental disaster in the making
Finding an alternative to phosphate fertilisers now so we don't face a global food shortage in the future.
We taught plants to be lazy; we need to find out what we bred out of them and breed it back in.
Prof. Jim Whelan, Professor of Plant Sciences, AgriBioscience, La Trobe University
Plant a seed, give it plentiful amounts of water and sunlight, and watch it grow. That’s all it needs, isn’t it? Not quite. Many plants, particularly high-yield food crops like rice and wheat also need phosphate-rich soil to flourish.
Phosphate is one of the key elements necessary for the growth of plants, animals and in lake ecosystems. It occurs naturally within rocks and other mineral deposits. During the process of weathering, rocks gradually release phosphorus as phosphate ions, which are soluble in water. It takes around one tonne of phosphate to produce 130 tonnes of grain. But today many soils are phosphate deficient, and farmers around the world need to purchase phosphates to maintain their yield and their livelihood.
Phosphate is a finite supply
Sadly phosphate is finite. Industrial farming has played a part in sucking this critical element out of our soil, which means we are running out of the high quality, readily accessible sources of phosphate. And in a world with an increasing demand for food, the cost of phosphate is going up. As a consequence, the price of food is going up – worldwide. While increases in the price of food can be absorbed in developed countries, it impacts hard in developing countries and leads to increases in malnourishment.
Around 140 million tonnes of phosphate rock is mined from the USA, China, Morocco and the Western Sahara every year. It’s processed then shipped and sold around the world. Some scientists predict in the not too distant future subsistence farmers will struggle to afford the phosphate needed to grow food for themselves and their families. Ultimately, the farming industry will struggle to grow enough food to meet the world’s food demands.
Predictions differ as to when the world’s phosphate supplies will run out. Some say it will last another 345 years; others say 100. But they all agree phosphate is a finite supply, and that something needs to be done.
We’ve already seen it happen in the Pacific, where once abundant phosphate resources on Nauru and Banaba Island have been depleted and are no longer viable.
An environmental disaster in the making
It isn’t just the future implications of a world with limited phosphate reserves that set alarm bells ringing. It is phosphate’s current impact on the environment too.
“At least 50 per cent, and sometimes as much as 70 or 80 per cent of phosphate applied as fertiliser eventually runs off. When phosphate washes into the water supply, it ends up in drinking water. It sweeps into groundwater, and from there it washes into rivers and lakes and causes algal blooms,” says Professor Jim Whelan of La Trobe University in Melbourne.
“Algal blooms become environmentally damaging very, very quickly. They produce toxins that can kill plant and animal life, which live in and around the water. Leached nutrients in water can change an ecosystem by promoting the growth of toxic species rather than native ones and can also completely overwhelm an ecosystem and kill everything in that ecosystem,” Professor Whelan explains.
Also the lower quality deposits have many contaminants such as arsenic and other metals. Again, in developing countries these contaminants are not separated due to the increased cost of processing and lead to the contamination of food and water.
Prof. Jim Whelan
Fighting the phosphate shortage
Professor Whelan is Co-Director of AgriBio: the Centre for AgriBioscience at La Trobe University in Melbourne, Australia. He and his 18-strong team are working hard to find a solution before a phosphate crisis hits. They’re growing thousands of plants on agar plates in controlled environments at La Trobe’s world-class AgriBio facility, and collecting data on their growth and behaviour.
The team’s research into a solution takes two strands: identifying the plant species and subspecies (ecotypes) that require less phosphate, and identifying the ones that use the phosphate available to them more efficiently.
“After World War II there was a worldwide food shortage. A lot of agricultural research was done into how to increase crop production. Some of this involved working on plant genetics, for example introducing or isolating dwarf genes so that plants don’t grow as high, which makes them easier to farm,” says Professor Whelan.
“Then there was the development of chemical fertilisers, including phosphates, which turbocharge the soil and help crops to grow. But there are all sorts of other, negative side effects that we’ve only become aware of in the past few decades.”
CLICK TO PLAY VIDEO: Watch Professor Jim Whelan explain the phosphate crisis and La Trobe University’s research to find solutions.
Growing smarter plants
Plants are like people, explains Professor Whelan. They have cells and DNA, and as time passes and an environment changes, natural selection occurs for the best performers.
“If we can identify a plant genotype or ecotype that is most phosphate efficient, we can select for that trait in crop varieties through breeding programs. In some cases, it’s a matter of breeding a trait back into a plant that has been lost. We taught plants to be lazy; we need to find out what we bred out of them and breed it back in.”
He’s doing exactly that with colleagues at Zhejiang University in Hangzhou, China, where he is a Visiting Professor. Together with Professor Huixia Shou at Zhejiang University, Professor Whelan oversees extensive field research into more efficient rice growing that has been underway for the past decade.
Rice is a dietary staple for more than half of the world’s population, particularly in Asia where up to 500 million subsistence farmers feed approximately three billion people with the rice they grow. Professor Whelan points out the research is focused on a worldwide solution — one that will work for modern, western farming systems and small subsistence farmers in Asia.
“We’re working on it,” says Professor Whelan, who estimates with appropriate funding, within five to seven years a solution could be quite literally flourishing in fields around the world.
La Trobe University
Discover further how La Trobe researchers are creating solutions to the phosphate crisis that the world’s food production relies on.