Why Does a Watermelon Sell for Twenty Yuan for Three Jin? Earthworm Castings Play a Big Role

Recently, Xihongsi Village in Kangzhuang Town, Yanqing County, Beijing, used earthworm castings instead of ordinary soil for the first time to grow soilless watermelons, which have now ripened and hit the market, with a picking price of 20 yuan each.

In April this year, grower Ma Dejun set aside 3 greenhouses for an experiment, laying down 18 cm of earthworm castings and hemp cake as the substrate for soilless watermelon cultivation. It is understood that earthworm castings are the excrement of earthworms fed on cow dung. The reason they are such an excellent organic fertilizer is that the earthworms themselves absorb only a small portion of the nutrient elements in the cow dung, while most of the nutrient elements remain in the castings. Moreover, through the earthworms' transformation, some harmful substances in the cow dung are broken down, making the castings non-toxic and harmless. They can not only serve as fertilizer for fruits and vegetables but also retain fertilizer and water and improve the soil, so they can be used both as a substrate and as a top dressing. In addition, the substrate made from earthworm castings plus hemp cake has physical characteristics such as water absorption, water retention and strong air permeability, and can promote photosynthesis in the vines, resist pests and diseases, and suppress harmful bacteria and soil-borne diseases, thereby improving the quality of agricultural products.

This year, Old Ma trial-planted two small watermelon varieties, L600 and Xinxiu. The ripe watermelons are slightly larger than those grown by ordinary methods. Ordinary watermelons weigh about 1.5 kg each on average, while the watermelons grown with the mixture of earthworm castings and hemp cake weigh about 1.7 kg each on average, and the total watermelon yield per greenhouse increased by 15%.