As the world’s population grows, farmers, economists, and policymakers urgently need to know whether food production will be able to keep pace.

Today we get an important insight into this complex problem thanks to the work of Mariam Barry at ENSTA ParisTech in France and few pals.

These guys have studied the yield of hybrid corn in the U.S. since 1985 and how this correlates with trends in biotech patents that announce new varieties. The thinking is that these patents could be used as a leading indicator of food productivity.

There is a long history of fear regarding food supplies. In 1798, Thomas Malthus famously predicted that population growth was set to overtake the ability to grow food, making widespread famine inevitable. His prediction turned out to be largely unfounded because the Industrial Revolution hugely improved yields.

Food production underwent another dramatic change in the mid-20th century. This so-called Green Revolution was the result of the widespread use of pesticides, herbicides, and fertilizers, along with increased mechanization. And it resulted in a steady increase in productivity for many crops.

More recently, the biotech revolution has begun to have an impact. Genetically modified organisms now dominate many crops in the U.S. and are thought to be increasing productivity (although other parts of the world have been more cautious about the technology).

Hybrid corn or maize is an important part of the U.S. food supply. Hybrids are bred from two or more inbred parent lines and can have important advantages over the parents alone. Advantages in yields per acre are often reported in patent documents and in later citations.

So Barry and co collected this data by mining all patents that mentioned hybrid corn since 1985, searching also for yield improvement data. Their goal was to see whether the reported improvements match those observed in the real world.

Accurate real-world data is hard to get, but an important source is land grant universities. These are educational institutions that were given land by the U.S. government in the 19th century to fund their future development. Many now farm this land, and some have published their crop yields for many years.

Barry and co collected this data from land grant universities in three states—Ohio, Kentucky, and Illinois. The data sets stretch from the mid-1990s to the present and are much more detailed than the data available from patents and other sources. They include the brand of seed used, along with yields and various other details.

Finally, Barry and co compared the data from the patents with the real-world yields to evaluate its predictive value.

After examining the results, the researchers say that hybrid corn yields are improving at a healthy rate. “By several different measures—from patents, field-test data and a forecasting model—we found improvement rates reasonably close and between 1.2% and 2.4% per year,” they say.

By contrast, the global population is growing at a rate of about 1.1 percent per year and the U.S. population is growing at about 0.8 percent per year.

So U.S. corn productivity looks set to increase and certainly match past improvements. Measured in bushels per acre, the corn productivity average in the United States more than quintupled between 1940 and 2015. Whether these gains can be translated into other parts of the world has yet to be seen.

The possibility of predicting future growth from patent data looks less promising. Barry and co say that before 2008, patent data accurately matched the observed rate of increase in the real world. But in 2008, something changed in the way patents and citations are used. One possibility is that at that time, the world of genetically modified food became dominated by just a few companies, such as Monsanto and Syngenta. And the practice of patenting seeds has become ethically charged. These factors may lie behind the change in patent practice.

That’s interesting work that throws some light onto the complex world of food production. Clearly the ability to feed ourselves is one of humanity’s most important priorities. This work reveals the complexities in understanding how productivity can be measured and analyzed in an advanced economy such as the U.S.

Nevertheless, many parts of the world still suffer food shortages. How much more difficult will this kind of analysis be on the global scale over which it is desperately needed?

Ref: arxiv.org/abs/1706.05911 : Food Productivity Trends from Hybrid Corn: Statistical Analysis of Patents and Field-test data