Ten years ago, the whole idea of eco-friendly farming was still very new in China and there were few practical examples for Lin to refer to. All he could do was experiment.

"Pigs, rabbits, chickens. I tried many different species," Lin says. "Nothing worked at first. They just died. With other investments, you can sometimes recuperate some money at the end, but with farming, once your animals die, you lose everything."

Economic pressure was immense. His family and friends tried to talk him out of farming. Lin's partner had a baby on the way and his friends thought he should not put almost all of his 4,000 yuan salary into the farm.

Lin decided to raise a breed of local chicken, the Beijing Imperial Oily Chicken. He desperately needed specialized knowledge, but since he refused to use chemicals on his farm, he had to think of other ways to keep his farm clean and the chickens healthy.

"Even if you clean the floor every other hour, you still cannot prevent the chickens from pecking the waste on the ground. That's how diseases spread. If one gets sick, they all get sick."

Lin went to the Beijing Academy of Agricultural and Forestry Sciences to consult the professors and learn about fermentation bed technology.

He invested 25,000 yuan to cover the floor of the henhouse with a 50-cm thick layer of wheat bran, rice husks and sawdust. The natural fermentation bed releases beneficial bacteria, which can break down chicken waste.

"Most of the time, farmers just use cheap sanitizers to save money and trouble."