According to an international team of researchers led by Dr Amy Bogaard from the University of Oxford, Europe’s first farmers manured and watered their crops as early as 6,000 BC.

Scientists have always assumed that manure wasn’t used as a fertilizer until Iron Age and Roman times. However, the team reporting in the Proceedings of the National Academy of Sciences has found enriched levels of nitrogen-15 – a stable isotope abundant in manure – in the charred cereal grains and pulse seeds taken from 13 Neolithic sites around Europe: Koufovouno in Greece; Slatina, Kapitan Dimitrievo, Azmak and Karanovo in Bulgaria; Ecsegfalva in Hungary; Vaihingen and Hornstaad-Hörnle IA in Germany; Sarup, Skaghorn and Damsbo in Denmark; Hambledon Hill and Lismore Fields in UK.

The study suggests that Europe’s first farmers used the dung from their herds of cattle, sheep, goats and pigs as a slow release fertilizer for crops. It reveals that early farmers recognized the inherent value of intensively managed land and sought to maintain it for their descendants. This new perspective overturns the traditional view held by scientists that Neolithic farmers were nomadic people who used slash and burn to create temporary farmland for agricultural crops.

“The fact that farmers made long-term investments such as manuring in their land sheds new light on the nature of early farming landscapes in Neolithic times. The idea that farmland could be cared for by the same family for generations seems quite an advanced notion, but rich fertile land would have been viewed as extremely valuable for the growing of crops. We believe that as land was viewed as a commodity to be inherited, social differences in early European farming communities started to emerge between the haves and the have-nots,” Dr Bogaard explained.

The team analyzed the abundance of stable carbon and nitrogen isotopes in 124 crop samples of barley, wheat, lentil and peas, totaling around 2,500 grains or seeds from Neolithic sites across Europe, dating from nearly 6,000 to 2,400 BC.

The study also has important implications for research into the diet of early farmers. Archaeologists rely on the stable isotope analysis of the skeletal remains to establish a signature, which provides information about what people once ate. The heavier stable isotope of nitrogen-15 found in manure mimics the isotopic effect of a diet rich in meat and milk.

It had been assumed that early farmers in northwest Europe had a diet full of animal protein. However, the new results suggest that the protein from cereal and pulse crops is much higher than previously thought, and that Neolithic crops were a staple part of their diet.

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Bibliographic information: Amy Bogaard et al. Crop manuring and intensive land management by Europe’s first farmers. PNAS, published online before print July 15, 2013; doi: 10.1073/pnas.1305918110