Fertilizers have been used for 8,000 years.

European farmers were among the first to use animal manure to fertilize their crops, dating back 8,000 years.

A fossilized specimen of barley from southwestern Germany. Photo: Oxford University.

A research team from Oxford University discovered that during the Stone Age, around 6,000 BC, farmers knew how to use animal manure from cows, sheep, goats, and pigs as a slow-release fertilizer for crops.

It was previously believed that the use of fertilizers for crops did not appear until the Iron Age, the Roman period. However, scientists have found that charred grain samples from Stone Age archaeological sites dating from 6,000 to 2,400 BC, taken from 13 locations across Europe, contain a large amount of the stable nitrogen-15 (N15) isotope, an abundant isotope found in fertilizers. This finding was published in the first issue of the journal Proceedings of the National Academy of Sciences, according to ScienceDaily.

Dr. Amy Bogaard of Oxford University said: "Farmers use fertilizers and apply long-term farming methods on their land, rather than a nomadic lifestyle. They quickly recognize the value of the land and seek ways to maintain it for future generations."

Previously, it was thought that the high N15 value of Stone Age human fossils was due to a diet rich in meat and dairy. However, the above results show that protein from grains was much higher than previously thought, and that crops were the primary food source in their diets during this period.

According to VnExpress - VT