Growing grass in greenhouses to raise geese: multiple benefits even during the winter idle season

    Once winter arrives, even with greenhouses covering the water surface, the temperature in the ponds cannot reach the level needed for whiteleg shrimp (Litopenaeus vannamei) to grow, so most shrimp farmers in Zhejiang enter their winter idle period. In Xinqiao Town, Xiangshan County, most of the shrimp greenhouses here sit idle, but at farmer Pan Xiaoqiu's home, the scene is quite different.

    Pan Xiaoqiu began using greenhouses to farm whiteleg shrimp in 2005. Whiteleg shrimp have very high water temperature requirements, and by November the local temperature is no longer suitable for shrimp farming. This situation lasts from November until March of the following year, and for nearly half a year the shrimp greenhouses can only sit empty. Every year when shrimp can no longer be farmed in November, Pan Xiaoqiu cleans the silt out of the shrimp ponds and waits until March or April of the following year to farm shrimp again. This silt at the bottom of the ponds often gives him a real headache. The feed for the shrimp and the shrimp droppings accumulate at the bottom of the ponds, producing large amounts of nitrogen, phosphorus and other substances. These substances pollute the water quality and are very unfavorable for shrimp farming the following year.

    In 2009, Pan Xiaoqiu heard experts from the aquatic technology extension station say that planting annual ryegrass (Lolium multiflorum) could absorb the harmful substances in the pond-bottom silt and make the pond-bottom soil just like that of a newly dug pond, so he scattered some grass seeds in the idle greenhouses. After planting annual ryegrass in the shrimp ponds, the microorganisms in the soil decompose the nutrient-rich substances, and after decomposition they become nutrient elements that annual ryegrass can absorb, such as available phosphorus and so on. Pan Xiaoqiu's farm covers 350 mu, with more than 100 shrimp greenhouses of various sizes. Planting annual ryegrass absorbs all the harmful substances in the pond-bottom silt, and the annual ryegrass can then be used, achieving two benefits at once.

    The temperature inside the greenhouse is constant and can always stay above ten degrees or so. The annual ryegrass planted inside grows especially well, and its growth rate is also especially fast. In just over 20 days it can grow to over 20 cm, more than 10 cm taller than on land. Moreover, this grass, like chives, grows longer the more it is cut. There is more and more annual ryegrass in the greenhouse, so how should all this annual ryegrass be handled?

    Xiangshan in Zhejiang is the hometown of the large white goose. The Xiangshan large white goose is a variety of the East Zhejiang large white goose, mainly produced in the Xiangshan area of Ningbo, and is famous for its large body and tender meat. After being raised for 70 days, it can reach a body weight of 4 kg. Pan Xiaoqiu did some calculations: a gosling costs just over ten yuan, and once grown, a large goose can sell for 70 yuan at market price. After deducting labor costs and so on, the profit per goose is about just over 20 yuan. Moreover,raising geesehas a short cycle. There is a local saying in Xiangshan: they eat and then poop right away, and by 60 days they are ready to sell. Raising two batches of geese just fills the idle period of shrimp farming.

    Pan Xiaoqiu adapted measures to local conditions and raised the large geese in this greenhouse covering more than four mu, while planting annual ryegrass in all the other greenhouses. Inside the greenhouse, a screen net was set up with steel wire and bamboo, and the geese's home was placed on the screen net, creating an above-ground farm inside the greenhouse. The screen net set up with bamboo stakes and steel wire is very sturdy, and wooden boards are laid at the joints between screen nets, so people can walk around freely in the middle to feed them without any problem. One roll of screen net costs 800 yuan, and a 3,000 sq m greenhouse used 3 rolls of screen net in total, costing 2,400 yuan. Although the one-time investment seems a bit high, the screen net is durable; compared with straw that must be replaced frequently, the cost is actually lower. As the saying goes, eat well and stay strong. The feed for the white geese is mainly grass, and these 8,000 large geese eat the annual ryegrass grown in the shrimp greenhouse. Because the annual ryegrass is grown by themselves, the cost is very low. By calculation, the cost of grass eaten by one goose per day is only 3 mao.