Evaluation of the primary soil fertility indices for the agricultural area of Yongqing County, Hebei Province

Yongqing County, as a pivotal pollution-free vegetable production base in the Beijing-Tianjin-Hebei region, has made significant contributions to ensuring the food safety of this region. However, there has been no systematic and comprehensive evaluation of Yongqing County's soil fertility, hindering the sustainable development of its green food industry. This study collected 338 soil samples from the arable layer (depth: 0~20 cm) throughout the county, including 155 from dry land, 84 from vegetable plots, and 99 from garden plots. Four soil nutrient elements including organic matter, total nitrogen, available phosphorus and potassium were determined using these samples. The results show that: The average contents of organic matter, total nitrogen, available phosphorus, and rapidly available potassium in the soil samples from Yongqing County's arable layer were 5.29×10^-3, 0.78×10^-3, 41.8×10^-6, and 197×10^-6, respectively. The soil fertility generally exhibited deficient organic matter and total nitrogen and abundant available phosphorus and potassium. In addition, the soil fertility of Yongqing County was graded and evaluated according to China's agricultural standard Green food-Environmental quality for production area (NY/T 391—2021). For land-use types like dry land, vegetable and garden plots, their organic matter and total nitrogen contents were mostly at level Ⅲ, and available phosphorus and potassium contents were primarily at level Ⅰ. The soil nutrient contents differed significantly in spatial distributions. Specifically, Longhuzhuang, Liujie, and Yangmazhuang townships in the southwest generally had higher soil nutrient contents than Caojiawu Township, Hancun and Lilancheng towns in the northeast. To efficiently develop the green food industry, Yongqing County needs to apply fertilizers scientifically and properly according to land-use types and actual planting situations and considering the soil texture and natural geographical factors. The specific measures are as follows: increasing the organic matter and total nitrogen contents in the soil by applying more organic and nitrogen fertilizers; applying more phosphate and potassium fertilizers to soil lacking available phosphorus and potassium, otherwise, the application of such fertilizers should be controlled.