CHANGSHA -- Zhang Dehui springs out of bed at around 4 am each morning, while the sky is still dark, swiftly dons his waterproof waders and heads for the crawfish fields.

Zhang is a rice and crawfish farmer from Nanxian county in Central China's Hunan province. He has devoted 136 mu (about 9.07 hectares) of land to a unique agricultural practice known as "crawfish-rice rotation," which involves planting rice during one season and rearing crawfish in fallow fields during the subsequent season.

"After midnight during the summer, temperatures tend to be relatively cool, making crawfish less irritable and easier to transport," Zhang said, adding that he has built a temporary shelter among the fields, allowing him to sleep there and check on the health of the animals.

"Every day, about 1,000 kilograms of crawfish are caught in my fields. By rotating crawfish and rice, I can make about 3,000 yuan (about $418) per mu annually in net income," said Zhang.