This peaceful field, about an hour and a  half north of London, has a big secret.

It looks a lot like pretty  much any other field around it. It has grasses, some flowers, and  it’s surrounded by a fence of trees.

But this field is home to an experiment that has been running for almost 170 years. It’s called Park Grass, and it’s the  birthplace of modern agricultural science. One of the greatest scientific  friendships of all time bloomed here.

So did one of the bitterest  scientific beefs of the 19th century. And research on the field is still going strong, churning out amazing discoveries  to this day with no end in sight. Here’s how a simple patch of grass became one of the world’s longest-running experiments. [♪ INTRO] Park Grass is a 2.8 hectare plot of land  that’s part of Rothamsted Research — an agricultural research  center in Harpenden, England.

It was one of the first  experiments set up there in 1856, which now has around twenty other  long-running experiments as well. The OG Park Grass site was really simple:  a field split up into 20 patches of grass, where each patch was basically its  own little experimental test subject. Each patch received a different  combination of nitrogen, phosphorus, potassium, magnesium,  and sodium fertilizers.

Then, every year at the beginning of summer, the experimenters would cut all the grass to make hay and measure how much they got. But who decided to set up this experiment in seemingly the middle of nowhere? And why?

It all started with a beautiful  scientific bromance between John Bennet Lawes and Joseph Henry Gilbert. Lawes was the typical Victorian  entrepreneur and philanthropist: he had money, he was interested in  science, and he wanted to help others. He lived at the Rothamsted estate,  which he’d inherited when he was only 8.

And when he was 20, he took over managing it. Lawes had always been interested  in chemistry and decided to give studying it a go at Oxford. But before he could get his degree, he left, saying he didn’t really  learn anything useful there.

Seems that he learned enough  though, because a few years later, he patented a new kind of fertilizer. It was made from mixing mineral  phosphates with sulfuric acid, and it worked so well that he set  up a factory to mass produce it. Which was good business because the  country’s population was growing, and it was still recovering  from the Napoleonic wars.

So people needed food, and for  that, they needed fertilizer. He tested his fertilizer and  a bunch of other compounds on the cabbages and turnips at his estate. And Lawes had plenty of  ideas for other experiments, but not the patience or scientific  rigor to carry them out.

That’s why, in 1843, he called  on Joseph Henry Gilbert — a chemist with an impressive scientific background who loved the finicky  nitty-gritty of doing science. He seems to have loved nothing more  than getting up in the morning, puttering around the fields  collecting all his data, then waking up the next day  and doing it all over again. RIP Joseph Henry Gilbert, you  would have loved Stardew Valley.

The two turned out to be a formidable duo. They worked together for 57 years, making them one of the longest  scientific partnerships in history.   Together, they took more than  40 acres of the land around the Rothamsted manor and created  all kinds of experiments to figure out how plants grow, and  what makes them grow even better. Which made these two scientists the  pioneers of modern agricultural science.

Each experiment was fairly simple. Take a plot of land; grow a  cereal, or a vegetable, or grasses, and then add different nutrients  to different sections of the land; and record what yields you get. Ok, wait a minute I hear you saying, this doesn’t sound like the start of an  agricultural science revolution.

It’s too… simple. Well, consider this. Up until this point, people had been dumping manure onto soil for thousands of years.

Later, they’d put ground up bones onto plots. But no one really understood which substances in these natural fertilizers  were helping plants out. It was all pretty much dump-and-see.

Lawes and Gilbert were two of several scientists who applied chemistry to this economic problem. And Lawes’ method of  tailor-making fertilizer en masse from individual components was  pretty ground-breaking at the time. Another reason for their pioneer status was how systematic and how massive  their experiments were.

While most agricultural chemists worked in labs, on small indoor versions of plants, Lawes and Gilbert got out there and  set up comparably huge experiments. This gave their work street  cred, or maybe field cred, to those who needed their research  the most — the local farmers. And, ok, I know you’re thinking, of course the guy with the fertilizer factories wants to  show that fertilizer is good for plants.

And yeah, sure, don’t give the rich  white Victorian guy too much credit. But Lawes was actually  really well liked by farmers. The farmers even raised money  for rich, white Victorian Lawes, who used it to build a new lab.

And when the lab opened, Lawes said “I must explain that the object  of these investigations is not exactly to put money into my pocket, but to give you the knowledge by which  you may be able to put money into yours.” But not everyone was so keen on  this dynamic duo and their work. This is the part of the story that  explains why we’re here today, some 160 years later, still talking  about these guys and their fields. It all has to do with an intense feud that  grew out of figuring out how plants grow.

But before we get to that, all science  needs funding, so let’s go to a quick break. Thanks to ACT for supporting this SciShow video! According to 2024 graduating class data,  nearly half of the US takes the ACT over every other college admissions test.

It makes sense. All colleges accept ACT scores. But ACT keeps getting better!

The enhanced ACT gives you the  shortest test time yet with 44 fewer questions and a choice of  whether or not to take a science section! If you prefer testing online or on  paper, you have that choice too. Plus, they let you try real ACT science questions before you take the test at quizme.act.org.

You can learn more about the ACT or  register for the next upcoming test at act.org/scishow, by scanning the QR code,  or by clicking the link in the description. Over in Germany, a scientist  named Justus von Liebig was also making a name for  himself as an organic chemist. He was certain that plants  got nitrogen from the air.

Liebig thought that ammonia in the  air gave plants their nitrogen, and that any fertilizer was just  there to add extra minerals. Meanwhile, Lawes and Gilbert  were convinced that plants got the nitrogen they needed from the soil — hence adding it to soil in the form  of fertilizer to make them grow. This scientific disagreement  turned into a full-on brawl.

Well, in the way that academic  brawls tend to play out, anyway: by throwing shade at each other in  their writings in academic journals. Along with the findings of  their experiments, of course. And all this was made all the more awkward because Gilbert had been Liebig’s student  before coming to Rothamsted.

Lawes and Gilbert called Liebig out for  his strictly laboratory-based approach, saying that, quote, “chemistry alone will  do nothing for practical agriculture.” Liebig had actually set up  field experiments of his own, where he doused the soil with artificial  fertilizers made from mineral salts. But… nothing happened. His just-minerals fertilizer  didn’t increase yields.

But Liebig wasn’t deterred. He kept arguing that nitrogen  fertilizers weren’t a thing. And kept going after Lawes and Gilbert.

Remarking, and again I quote: “It  is all humbug, most impudent humbug… Lawes and Gilbert hitch on to me like vile vermin and I must get rid of them by all means.” Which by Victorian standards is pretty gloves off. Meanwhile, Lawes and Gilbert  kept running their experiments — including Park Grass — and showing  that nitrogen did bump up crop numbers. And theirs became the accepted theory.

It wasn’t until after Liebig’s death that  biologists demonstrated that plants could get nitrogen from the air, but only thanks  to nitrogen-fixing bacteria on plant roots. That feud was part of what  kept the Park Grass experiment running for all of Lawes’ and Gilbert’s lives. But why is it still running today?

Well, what started out as a way to  increase hay yields quickly became fertile ground for studies on  evolution, ecology and climate. Areas of science that continue  to be super relevant today. Let’s start with evolution.

Part of the reason Lawes selected the  field near his manor house for the site of Park Grass was the abundance of  grasses and flowers growing there. But a couple of years into the experiment, they noticed that the plots looked very different. Almost as if they’d been  sewn with different seeds.

What Lawes and Gilbert had managed  to show was local adaptation: that a population of organisms evolves  to be more well-suited to its local environment than other members of the  same species that live somewhere else. Call it evolutionary home team advantage. Usually when scientists  talk about local adaptation, they’re talking about big geographical distances.

But Park Grass showed that it can  happen over small ranges as well.   And this local adaptation actually  ended up weeding out plants that weren’t amazingly adapted to whatever  soil conditions were at each plot. And that meant, over the 150 plus years  that this experiment has been running, there’s been a steep drop in  plant and pollinator diversity. The fertilized plots now contain  one fifth as many types of flowers and half the number of  pollinating insects compared to plots that haven’t had any fertilizer applied.

So Park Grass also showed  the big trade-off between productivity and biodiversity—something  that’s super important if we’re thinking about feeding all the humans in the world while trying to keep natural ecosystems thriving. Now, when it comes to climate, we need  to get into another important part of Park Grass that we haven’t  mentioned yet. The archives.

Every year, without fail, researchers have kept samples of grasses and soils from the fields. Which means there are now  more than 300,000 samples sitting in jars at Rothamsted. There are so many, in fact,  that researchers recently had to move the archive to a bigger building!

All those samples are basically a time capsule for what was happening to those  plants, and the climate, at the time. Scientists have used them to track air pollution, and saw a big drop in sulfur after the UK started shutting down their coal-powered factories. They could even pick up the  fallout from atomic bomb tests done all the way in the Nevada desert in the US!

So Park Grass really did become  about more than just growing hay… or creating fertilizers… or even  creating agricultural science! But that doesn’t happen by accident. The kinds of ultra-sensitive measurements  needed to detect minute traces are only possible now thanks to better  chemistry techniques and technology.

So you need a couple of  forward-thinking scientists to keep an experiment going long enough  for that tech to be invented. Even during their time, Lawes and Gilbert could see that chemistry techniques  were changing rapidly. They knew that in five or ten years, other researchers would be able  to do studies they couldn’t.

But they probably never could  have imagined all the experiments that would be done on their humble  patch of grass over the next century. Today, DNA extracted from soil at  Park Grass has been used to catalogue what kinds of microbes live in the earth and how different fertilizers can  change that soil ecosystem. And by analyzing the carbon content  of soils from different years, researchers have been able to create a model of how a changing climate affects soil quality.

That model, called RothC, is now a crucial  part of global climate forecasting and is helping researchers predict how climate  change might affect the food we eat. And maybe that’s the sign  of true scientific talent. It’s not just in the experimental  design and the questioning, but the optimism for progress and innovation.

Since 1856, Park Grass has  been modified a few times and those 20 patches have now become 101. But those who work on the experiment say that there are no plans to stop it any time soon. This little plot of grass is still  sprouting new scientific discoveries.

And the two scientists who started it all? Well, Lawes died in 1900, with Gilbert  following a year later in 1901. The two were buried just a few feet  from each other in the same cemetery.

A scientific bromance immortalized forever beneath the grass of the English countryside. [♪ OUTRO]