Why One Neolithic Scottish Settlement Didn’t Need Any Fertilizer

People living in Western Europe and on the British Isles during the Neolithic Period (10000 to 2200 BC) had already discovered the powers of manure-based fertilizer to increase crop yields. In fact, the earliest Neolithic farmers in the lands of modern-day England and Wales were spreading dung fertilizer on thick, recycling nutrients enthusiastically in order to spur greater food production.

But it seems that farmers who occupied the northernmost section of the islands, in what is now Scotland, weren’t all so quick to participate in the fertilizer revolution. As reported in a study just published in the journal Antiquity, an analysis of ancient agricultural practices at a Neolithic site near Aberdeenshire, Scotland showed that Neolithic farmers living in the region 6,000 years ago chose to forgo the use of fertilizer. It seems they got along fine without it, even while manure was being heavily used in adjacent regions

The Fertilizer-less Fertile Soils of Neolithic Balbridie

The Neolithic site analyzed in this eye-opening study is known as Balbridie. Located near Scotland’s east-central coast, Balbridie features a Neolithic timber long house (an ancient type of barn used for crop storage) that was constructed on the south bank of the River Dee. Dating of the site has revealed that Balbridie was one of the oldest occupied settlements in all of Scotland, having been founded sometime between 3400 and 4000 BC.

Plan of part of the excavation site at Braes of Ha’Breck, where the Neolithic fertilizer data was obtained, showing the location of the grain-rich soil. (Photographs and plan by A.S. Thomas and D.H.J. Lee / Antiquity Publications Ltd).

Excavations have been performed at the site for more than 40 years, and recovery efforts have unearthed large quantities of well-preserved cereal grain. The long hall burned to the ground in a raging fire sometime in the early fourth millennium BC, but a cache of more than 20,000 individual cereal grains were found protected beneath the rubble.

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It was these grain samples that the researchers involved in the latest study analyzed, using isotope detection technology. They were searching for the fingerprints left behind by fertilizer applications, which would be found in the grain’s ratios of carbon and nitrogen isotopes.

What they discovered was unexpected, given what is known about farming practices in Neolithic Britain.

“The stable isotope analysis revealed very low nitrogen levels, showing that the crops were not grown on manured soils,” explained study lead author Dr. Rosie Bishop, an archaeologist from the University of Stavanger in Norway, in an Antiquity press release. “The large size and number of the grains recovered suggest that during this first phase of farming, the soils were productive without the need for manuring.”

This is a most unusual discovery. Previous research on ancient farms in England, and in Western Europe as well, have found evidence of significant manure-based fertilizer use in every case.

Since animal dung’s capacity to act as a potent fertilizer was well-known in Western Europe, presumably farmers in Neolithic Scotland were aware of its reputed effectiveness. If they chose not to use it, the soil in east central Scotland must have been fertile enough not to require any supplement, at least at that time.

The grain-rich layer at the Braes of Ha’Breck site showing the dark, carbonized grain in house 3. (A.S. Thomas and D.H.J. Lee / Antiquity Publications Ltd).

Fertile Neolithic Balbridie: Anomaly or Something Else?

While Neolithic farming practices departed from the norm along one section of Scotland’s North Sea coast, the situation was quite different elsewhere.

The scientists involved in this new study looked at cereal grains recovered from three other Scottish sites. One of these was a location known as Dubton Farm, which is in the Angus council area just south of Aberdeenshire. The two other ancient agricultural settlements, known as Skara Brae and the Braes of Ha’Breck, are both found on the Orkney Islands, 10 miles (16 kilometers) off the northern Scottish coast.

All of these sites were occupied, and their land used for growing crops in the third and fourth millenniums BC, making them roughly contemporary with Balbridie. But testing revealed that manure was used as fertilizer in all three locations, in contrast to what was discovered in Balbridie.

“Cultivation practices were similar to those implemented elsewhere in Neolithic Europe, involving intensive manuring of permanent plots, and indicating a sustained investment in the productivity of the land,” Dr. Bishop and her co-authors wrote in their Antiquity paper.

At least for now, Balbridie is the only Neolithic agricultural settlement known to have rejected the use of manure-based fertilizer. The naturally fertile soil conditions farmers enjoyed there must have been relatively unique, which would explain why farmers residing in other parts of ancient Scotland wouldn’t have been able to follow their example. It is interesting that fertilizer was widely used by farmers at the Angus site, which was geographically adjacent to Balbridie but apparently didn’t share its soil.

Meanwhile, the study of the plots cultivated by Orkney farmers revealed one good reason why they would have needed to use a lot of manure-based fertilizer.

“At one of the Orkney sites we were also able to show that these early farmers grew their crops over a range of different soils, suggesting they grew their crops quite extensively around the landscape or that different farms were storing their crops in a communal store at the site,” Dr. Bishop observed.

If these farmers needed to exploit different soils to grow enough crops to feed their people, it suggests they would have experienced shortages if they had not used manure-based fertilizers. In these circumstances, it was inevitable that they would have used manure fertilizer to boost production as much as possible. It would have been especially vital to use it on lands that were considered marginal from an agricultural perspective.

This Neolithic stone building at Knap of Howar, Orkney, from the early Neolithic, is one of the oldest surviving houses in northwestern Europe, and whoever lived there used fertilizers to avoid starvation. (Me677 / Public domain)

Neolithic Scots: Adaptability and Cooperation Meant Survival

“The variability of the cropping strategies identified highlights the adaptability of early farming practices,” Dr. Bishop said, summarizing the overall picture as it pertained to agricultural activities in Scotland thousands of years in the past.

Likewise, there was a cooperative element to ancient farming practices in the British Isles that would have helped ensure there was enough to eat for everyone, in bad times as well as in good.

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“The evidence for the storage of harvests from different microenvironments and/or years within the structures at Balbridie and the Braes of Ha'Breck implies that Neolithic farmers implemented measures to buffer against crop failure, creating a level of economic resilience to environmental and social uncertainty,” the study authors wrote.

It is likely that further research will find more evidence of the adaptability and cooperative spirit that defined agricultural activity in Scotland in Neolithic times. It is certainly possible that farmers in other parts of Scotland didn’t have to use fertilizer and that the agriculturalists at Balbridie were not unique, and future excavations may very well prove this to be true.

Top image: A recent study has revealed that one particular Scottish settlement in the early Neolithic period didn’t use manure-based fertilizers though farmers adjacent to them did. Cow manure like this is still highly recycled and used all over Africa and Asia. Source: wisawa222 / Adobe Stock

By Nathan Falde