December 5 is the 9th World Soil Day. This year's theme is "Soil: the source of food". It is a cold winter, and the black land in Northeast China has entered the slack winter season, accumulating momentum for grain production next year. As the most fertile soil in the world, black soil is suitable for farming and is the foundation for ensuring world food security. Liu Jie, president of Heilongjiang Institute for the Protection and Utilization of Black Soil, said that black soil in the world is mainly distributed in the Great Plains of Ukraine and Russia, the Great Plains of the United States to Canada to the north, Northeast China and the Pampas Grassland of South America from Argentina to Uruguay. The black soil areas in Northeast China are mainly distributed in Heilongjiang Province and Jilin Province, the northeast of Liaoning Province and the "Fourth Eastern League" of Inner Mongolia Autonomous Region. The Northeast granary is the "stabilizer" and "ballast" of China's food security. At present, the continued COVID-19 and meteorological disasters have increased the uncertainty of the world food market. In this context, it is particularly important to ensure world food security and protect the black land known as "giant pandas in cultivated land". In recent years, many measures have been taken to strengthen the black land protection in the black soil area of northeast China, consolidate the basis for stable grain production, and contribute to the "China Plan" for the world black soil protection. A few days ago, in a rice field in Shuangquan Village, Baoqing Town, Baoqing County, Heilongjiang Province, the dark soil after deep ploughing and deep loosening this autumn glowed in the sun. "After the autumn harvest, the straw will be turned back into the field deeply, and the next spring ploughing will use the composting agent to speed up the straw decomposition, making the farmland more fertile." Wang Libo, secretary of the party branch of Shuangquan Village, said that in addition, it also combined manure returning to the field, soybean corn rotation and other ways to protect black land. "The organic matter in the field has increased, and the rice produced has good quality and high yield. This year, the rice yield per mu will reach about 1200 jin." Wang Libo said. Heilongjiang Province is located in the core area of northeast black soil area, with 257.9 million mu of cultivated land, ranking first in China. The area of typical black soil farmland is 156 million mu, accounting for 56.1% of the typical black soil area in Northeast China. In recent years, Heilongjiang Province has explored the formation of the "Longjiang Model" for black land protection, which mainly includes straw burial and returning to the field, straw crushing and returning to the field, and straw mulching and no tillage, and the "Three Rivers Model", which mainly includes rice straw burial, rotary tillage and original stubble pulping and returning to the field, becoming the main technical model for black land protection in China. To protect the black land, we must adhere to science and technology first. In the soil laboratory of the Agricultural Science and Technology Service Center of Beidahuang Group Honghe Farm Co., Ltd., agricultural technicians are drying and crushing soil samples. "Since the last ten days of October, we have collected and tested 600 soil samples. Next year, we can apply fertilizer through soil testing formula to improve fertilizer efficiency and reduce soil hardening." Wang Wei, director of the company's agricultural science and technology service center, said that this comprehensive "physical examination" of black soil farmland can also effectively find out the current situation of farmland quality and gradually establish a farmland quality database. Soil and water loss is one of the important causes of black land degradation. Erosion gully is the main form of water and soil loss in the process of occurrence and development, which will cause the black soil layer to become thinner year by year, soil organic matter loss and farmland fragmentation. Not long ago, the reporter saw at the site of erosion ditch treatment in Battle Village, Sandao Town, Baiquan County, Heilongjiang Province that several workers were lining up two fingered wicker longitudinally along the bottom of the erosion ditch, and pressing it horizontally every two or three meters