The shift from dairy waste to agricultural wealth is transforming farming practices in northern China. For 55-year-old veteran farmer Zhu Xiangchen, the benefits of using fermented liquid manure from a local dairy farm are clear. "The crops treated with biogas slurry are visibly stronger and more vigorous," he says, standing beside his towering cornfield.
As his vehicle passes through vast stretches of corn, Zhu, who knows the local soil's sandy, low-organic-matter composition intimately, explains his calculations. "We used to rely on expensive chemical fertilizers that hardened the soil. Now, using the organic biogas slurry from the dairy farm, I've improved my soil over three years while using less fertilizer and getting higher yields. The dairy buys back all my corn silage at market price. It's a profitable equation."
The conversation reveals a clear, circular chain: cow manure is transformed into biogas slurry, which enriches the soil and grows feed for the cows. This waste-to-resource model addresses the once-daunting challenge of managing manure from large-scale dairy operations. At the Modern Dairy Tongliao Farm, located in Xi Wulan Village, Liaohe Town, Tongliao Economic and Technological Development Zone, a 5,000-cubic-meter fermentation tank serves as the "green heart" of this entire operation. An automatic manure-cleaning system collects waste from over 12,000 cows around the clock.
The manure undergoes 21 days of anaerobic digestion, producing biogas and residue. "The farm generates 30,000 cubic meters of biogas daily, which translates into 9.12 million kilowatt-hours of electricity per year. This power meets all our daily electricity and heating needs, saving 4,125 tons of standard coal and reducing carbon dioxide emissions by 48,000 tons. Energy alone saves us over 10 million yuan annually," says Liu Hongyu, General Manager of Modern Dairy (Tongliao) Co., Ltd.
The value extraction continues after fermentation. The solid residue, after solid-liquid separation and drying, becomes high-quality bedding material for the cows, replacing rice husks and sand. This alone saves 18 million yuan per year in bedding costs. The used bedding is then returned to the collection tank to be re-fed into the fermentation system, completing another loop. The separated liquid, or biogas slurry, is rich in nitrogen, phosphorus, and potassium鈥攁 natural "ecological nutrient solution" ideal for sandy and saline-alkali soils.
The farm has partnered with the local community to launch a "free biogas slurry for silage" model. It provides the slurry to over 1,000 nearby farmers for use on nearly 20,000 mu (approximately 1,333 hectares) of farmland, and then buys back their corn silage at market prices. This model deeply binds the dairy and the farmers. For the company, it solves the problem of slurry utilization and secures its feed supply. For farmers, it's a direct path to cost savings and increased income. "We save on fertilizer costs, and the improved soil leads to much higher yields," Zhu Xiangchen recalls. In his first year using the slurry, his yield increased by nearly half a ton of corn silage per mu, netting his 1,350 mu farm an extra 400,000 yuan compared to previous years.
This isn't just one farmer's success story. Data shows that over seven years, the soil organic matter content in fields treated with biogas slurry has risen from 0.9% to 1.7%, and the quality of the arable land has improved significantly. Fertilizer use has been reduced by about 30% per mu. This enhanced soil fertility has directly boosted the average local corn silage yield from 3 tons per mu to 3.5 tons per mu, generating an average additional income of about 280 yuan per mu. What was once a pollution burden has become a fully-valued green treasure. This "manure revolution" not only protects the ecological baseline but also creates new profit centers, charting a path for green agricultural development where ecology, production, and living standards all benefit in a win-win scenario for rural revitalization.