Heilongjiang Liushan Farm is located in Songnen Plain, Tailai County, Qiqihar City, Heilongjiang Province. It is one of the only three cold black soils in the world, with high latitude, high cold and long sunshine time. It belongs to the lower limit of the first accumulative temperate zone in Heilongjiang Province, where the annual average temperature is 3.6 ℃ and the annual effective accumulative temperature is between 2800℃ and 2900℃. The annual frost-free period is 137-140 days, and the annual average precipitation is 371.1 mm. Rich in water resources, the main irrigation canal system is Choer River system, originating at the southern foot of the Greater Hinggan Mountains. There is no pollution source in the upstream, the river is clear to the bottom, the arable area is flat, and the composition is black soil, meadow soil and chernozum soil rich in organic matter. Due to the unique natural conditions and fertile soil, the planting of green selenium-rich rice and organi...