Method for symbiotic rotational culture of rice, crayfishes, ducks and crabs

The invention discloses a method for symbiotic rotational culture of rice, crayfishes, ducks and crabs, and relates to the field of agricultural ecological cultivation. The method comprises the following steps: in the middle ten days of January, digging cultivation ditches around a rice field, planting waterweed and typha angustifolia, arranging an anti-escape net around the rice field, placing juvenile crayfishes into the rice field in the first ten days of April, artificially cultivating rice seedlings in a greenhouse in the middle ten days of May, transplanting the seedlings into the rice field, irrigating water into the rice field, adding a nutrient into the water, placing juvenile crabs into the cultivation ditches and the rice field in the middle ten days of July, feeding ducks in abreeding shed in the last ten days of August, arranging fences on the periphery of a rice stubble field in the first ten days of November, and breeding the ducks in the rice field. The ducks, the crayfishes and the crabs are