Analysis of Soil Nutrients at Different Soil Fertility Levels in Black Soil Dryland Farmland in the West Foot of the Greater Khingan Mountains

In order to protect and cultivate the black soil, the soil fertility status and nutrient differences of different fertility grades in Sertara Farmland at the western foot of the Great Khingan Mountains were investigated through field random sampling and indoor nutrient analysis.The results showed that the contents of organic matter, available phosphorus and slow-acting potassium had a good correlation with the soil fertility grade. With the increase of soil fertility grade, the content showed an upward trend; The organic matter content showed obvious changes, the average content of the first grade was 62.93 g·kg^-1, the fifth grade was 36.71 g·kg^-1, and the first grade was 1.71 times of the fifth grade; The content of organic matter in the first to fourth grade of land belongs to the very rich level of soil nutrient grading standard of the national soil survey, and the fifth grade land belongd to the rich level.The available phosphorus and slow-acting potassium in the first grade were 1.36 times and 1.31 times of those in the fifth grade. pH, total nitrogen, alkali-hydrolyzable nitrogen, and available potassium also increased with the increase of soil fertility grade. Total phosphorus and total potassium did not change regularly, and there were no significant difference between different soil fertility grades.The average content of available copper, available boron and available zinc in different soil fertility grades was medium, the average content of available manganese and available molybdenum was rich, and the content of available iron was extremely rich.