Rothamsted’s 180-year harvest

For nearly two centuries, the exper­i­ments at Rotham­sted Research have offered invalu­able insights into the dynamics of soil health, crop yields, and envi­ron­mental inter­ac­tions. As agri­cul­ture evolves, Rotham­sted remains a corner­stone in the pursuit of sustain­able farming, helping address the pressing chal­lenges of climate change and food secu­rity.

The Classic Exper­i­ments are the name of the long-term trials created by Sir John Bennet Lawes and Sir Joseph Henry Gilbert between 1843 and 1856. Though not initially intended as long-term studies, the value of repeating the trials became clear. “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,” said Sir John Lawes in 1854. One of the most remark­able aspects of Lawes’ and Gilbert’s work was their fore­sight in retaining samples of crops and soils taken for chem­ical analysis.

Succes­sive gener­a­tions of scien­tists have continued to add to the collec­tion, and today, Rothamsted’s archive contains around 300,000 samples, including oven-dried, ground, and unground plant mate­rial as well as soils, manures, and fertilisers applied to exper­i­mental plots. The Broad­balk field, which had been in arable use for centuries, saw its first exper­i­mental crop of winter wheat sown in 1843 and harvested in 1844. Every year since, wheat has been grown and harvested from the same field, a testa­ment to long-term research conti­nuity.

Rotham­sted during the war

Despite staffing short­ages, the trials continued unchanged during both World Wars. The farm manager’s wife took over during his call-up and report­edly became the first to run it at a profit. Resource­ful­ness was key – when glass was unavail­able for storing samples, staff brought tins from home. Even under such pres­sure, Rotham­sted continued to provide crucial data. Dr Andy Gregory, head of the Rotham­sted long-term exper­i­ments, reflects on the impor­tance of these historic trials. “I’ve been at Rotham­sted for just over 20 years now, and I continue to see how the trials affect our under­standing of current agri­cul­tural chal­lenges, and how they lay the ground­work for solu­tions to prob­lems we haven’t expe­ri­enced yet,” he says.

What the trials look at

The trials were initially designed to inves­ti­gate how different nutri­ents affect crop growth. This involved testing nitrogen, phos­phorus, and potas­sium indi­vid­u­ally and in various combi­na­tions. Nitrogen, in partic­ular, was applied at different rates using inor­ganic forms. Each trial also included a control plot (no inputs) and another that received farm­yard manure, offering valu­able compar­isons over time. A distinc­tive feature of these trials, intro­duced by Lawes and Bennet, was growing the same crop year after year. While not common in 19th-century agri­cul­ture, they delib­er­ately adopted this approach, believing it was the most effec­tive way to under­stand and precisely deter­mine the long-term nutrient require­ments of crops.

“Since Lawes’ death, there have been modi­fi­ca­tions, such as more plots added to Broad­balk to test the effects of P in the pres­ence of N, K, Na, and Mg,” explains Andy. “Chalk has been applied inter­mit­tently since the 1950s to main­tain pH at a level at which crop yield is unaf­fected. It was not until the First World War that the exper­i­ment was hand weeded, but the labour shortage allowed weed compe­ti­tion to become so severe that yields declined by the 1920s. To control these weeds, the exper­i­ment was divided into five sections, with one section bare fallowed each year, and the yields recov­ered.”

Since 1964, herbi­cides have been used on all the plots, except for half of one section where weeds are allowed to grow unless fallowing becomes neces­sary. The current wheat variety is in its sixth and final year of cultivation, a prac­tice that aligns with the typical six-harvest cycle before a change is made. This autumn, it will be replaced by a new variety from the AHDB Recom­mended List, reflecting what’s currently a popular choice for farmers. This new variety is a collab­o­ra­tive deci­sion made by a committee that includes scien­tists, agron­o­mists, and farm staff.

Long-term data opens doors

“The wheat is always a bread-making wheat, some­thing which has good disease resis­tance, and some­thing that we’re confi­dent we can get the seeds for the next five years,” explains Andy. “This high­lights the key prior­i­ties in their selec­tion process: Ensuring the wheat is suit­able for bread produc­tion, resilient against common diseases, and consis­tently avail­able for future planting. As new tech­nology continues trans­forming agri­cul­ture, Andy high­lights a signif­i­cant devel­op­ment in how Rotham­sted moni­tors soil. “There are new non-destruc­tive ways to test soil being intro­duced through sensors, but more work is still needed before it completely replaces tradi­tional chem­istry-based methods.”

This indi­cates an exciting shift toward more effi­cient and less inva­sive soil analysis, though tradi­tional tech­niques remain essen­tial. Rothamsted’s long-term data opens doors for unex­pected discov­eries. “One student contacted us as he knew we had soil from before the plastic era; he was able to show convinc­ingly the accu­mu­la­tion of microplas­tics in recent decades in the plots where we use inor­ganic fertiliser and manure, but there was also accu­mu­la­tion under the nil plot as well,” explains Andy.

The Broad­balk field has been in arable use for centuries.

Rothamsted’s historic archive stores over 300,000 samples of soils, crops and fertilisers.

Climate-changing weather patterns

“There’s no doubt that climate change is affecting our weather,” he adds. “Lawes first started collecting rain­water during the 1850s, and we’ve had air temper­a­ture data since the 1870s.” A student’s research recently under­scored the signif­i­cance of these long-term records. “He could iden­tify about 10 different weather patterns and see that some which were more common in the 19th and early 20th century are less common now.” This research power­fully demon­strates how Rothamsted’s exten­sive histor­ical datasets are crucial for iden­ti­fying and under­standing the real-world impacts of climate change on agri­cul­tural patterns.

Future of Rothem­sted

While the future of Rotham­sted remains open-ended, the spirit of discovery endures. “Without knowing exactly what will happen, I think we can be confi­dent that things will change, and new things will be measured, and they will be used in new ways, based anec­do­tally on what’s happened so far.” Rothamsted’s long-term trials are an irre­place­able global asset, providing contin­uous, invalu­able data that tran­scends imme­diate appli­ca­tions. “One thing about the clas­sical exper­i­ment trials, which I find fasci­nating, is that I don’t know where the data I’m collecting could be used,” notes Andy. “It could be another 100 years from now until they are used to their full poten­tial.”