Neolithic People Used Manure Fertilizer as Early as 6,000 B.C.

Europe's first farmers used agricultural techniques far more advanced and much earlier than previously thought, according to a research team from the University of Oxford, which states that Neolithic farmers used manure to fertilize crops as early as 6,000 BC.

Until now, it has always been assumed that manure was not used as fertilizer until the Iron Age and Roman times, but this latest research reveals in the charred remains of ancient cereal grains taken from 13 Neolithic sites around Europe notably high levels of nitrogen-15 - a stable isotope abundant in manure. The research is based on carbon and nitrogen analyses of 124 crop samples of barley, wheat, lentils and peas, totaling around 2,500 grains or seeds. The charred remains represent harvested crops that were destroyed by fire while in storage. The cereal and pulse samples were collected from a number of European sites, including the UK, Greece, Bulgaria, Denmark and Germany.

The evidence suggests that rather than leading a nomadic lifestyle, the early people took a long-term approach to cultivating land by using dung from ruminants as a slow-release fertilizer for crops. Because dung breaks down slowly and crops benefit from its use over many years, its use as fertilizer is indicative of a long-term approach to farming, the researchers report.

"These results point to a different kind of farming where they were making fixed investments in land that they intended to hang onto and pass onto future generations," research leader Amy Bogaard told BBC News.

Bogaard said the transition from nomadic to farming lifestyle would have had great social effects as well, as people would claim different plots of land and ultimately fight over land rights in the future.

"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," Bogaard said in a news release.

"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."

Territorial disputes over quality land for the sake of growing crops may help explain documented historical evidence of extreme violence, the researchers state, citing the example of a sixth century BC Neolithic mass burial site in Talheim, Germany, which preserves the remains of a community killed by assailants wielding stone axes like those used to clear the land.

Finding evidence of rampant grain consumption and cultivation also suggests that the early people had a diet less meat-centered than previously thought, the researchers report.

Bogarrd and her colleagues' findings are published in the journal Proceedings of the National Academy of Sciences.