Depending on the variety, for common varieties such as navel oranges, 56 plants are planted per mu, and the cost of raising seedlings is about 300 yuan, the planting cost is about 300 yuan, and the annual management cost is about 500 yuan. Therefore, the investment in the first year should be 1 100 yuan/mu, and the annual management fee per mu is about 600 yuan, and so on. Of course, it also depends on the terrain, traffic location, soil play and so on. If land is reclaimed from the sea, the cost will increase a lot.