The promise of self-fertilising crops

By the end of the 20th century, some scientists predicted that the planet’s limited food resources would restrict population growth. US ecologist Paul Ehrlich, in his 1968 book The Population Bomb, suggested unchecked population growth would lead to widespread starvation. However, a scientific advancement decades earlier dramatically altered global food production and the planet’s carrying capacity.

A Century of Fertilizer Innovation

In 1909, German chemists Fritz Haber and Carl Bosch developed a process to create fertilizer (ammonia) from atmospheric nitrogen. This bypassed the natural nitrogen cycle, which relies on nitrogen-fixing bacteria. By the 1960s, this technique was significantly increasing crop yields. Today, synthetic fertilizers support approximately half of the world’s population.

Did You Know? In the USA alone, the Department of Agriculture estimates that farmers spent nearly US $36billion on fertilisers in 2023.

The Promise of Self-Fertilizing Crops

Researchers at the University of California, Davis (UC Davis) are exploring methods for crops to produce their own fertilizer. According to Eduardo Blumwald, a professor of plant sciences at the university, the results are promising. Nitrogen-fixing bacteria require an enzyme called nitrogenase, which is sensitive to oxygen. Plants like beans and peas naturally provide a low-oxygen environment for these bacteria in root structures called nodules.

Most cereal crops – including wheat, rice, barley, and oats – lack this ability. The UC Davis team, using the gene-editing tool CRISPR, has engineered wheat plants to produce a chemical that encourages soil bacteria to form biofilms, which allow nitrogen in while blocking oxygen. This technique has also been successful with rice plants.

Expert Insight: The development of crops that can self-fertilize represents a potential shift in agricultural practices, offering a pathway to reduce reliance on synthetic fertilizers and mitigate some of the environmental consequences associated with their use.

While field trials are still pending, greenhouse experiments have been successful. A company is reportedly interested in acquiring the technology, and further projects are underway to develop sorghum and millet for use in Africa.

Implications for Global Food Security

This breakthrough could be particularly beneficial in developing countries, such as those in sub-Saharan Africa, where fertilizer use is limited due to cost and farm size. Blumwald suggests that crops stimulating natural fertilizer production in the soil could significantly improve food security in these regions. Approximately 200 million hectares of US farmland are planted with cereals.

Even a ten per cent reduction in fertilizer use on US farmland could result in savings exceeding a billion dollars annually. Beyond economic benefits, reducing fertilizer use could also lessen environmental damage. Plants only absorb 30 to 50 per cent of applied nitrogen, with the remainder contributing to algal blooms in waterways and the release of nitrous oxide, a potent greenhouse gas.

Frequently Asked Questions

What is the Haber-Bosch process?

The Haber-Bosch process, developed in 1909 by Fritz Haber and Carl Bosch, is a method to convert atmospheric nitrogen into ammonia, a key component of synthetic fertilizers.

What are biofilms and why are they important in this research?

Biofilms are sticky layers formed by bacteria. In this research, they allow nitrogen into the soil while blocking oxygen, creating an environment conducive to nitrogen fixation.

Which crops have been successfully engineered to promote self-fertilization?

The UC Davis team has successfully engineered both wheat and rice plants to promote self-fertilization through the creation of biofilms.

As research progresses, will these self-fertilizing crops truly lessen our dependence on synthetic fertilizers and contribute to a more sustainable agricultural future?