Evaluation of the Effect of Modified Phosphogypsum Landforming Soil on Lettuce Growth and Its Safety

The low comprehensive utilisation rate of PG has become a key issue restricting the sustainable development of the phosphorus chemical industry, and modifying PG to make land is a new way to improve the utilisation rate of PG resources and increase the amount of arable land. In this paper, lettuce was used as the test crop for potting simulation experiments, and three proportions of PG and soil were set up to study the effects of different treatments on the physicochemical properties of lettuce inter-root soil, the growth and development of lettuce, and to evaluate the quality of the land-creation soil environment and the safety of lettuce consumption. The results showed that the content of quick-acting phosphorus and quick-acting potassium increased significantly in all treatments compared with CK, with the T1 treatment showing the best enhancement effect, with a significant increase of 369.06% and 53.24% compared with CK; Among all the treatments, the T1 treatment was the most effective in enhancing the biological traits of lettuce, with biomass, stem thickness and stoutness index significantly enhanced by 30.06%, 17.70% and 28.77%, respectively, compared with CK; The heavy metal content of each treatment soil did not exceed the GB15618-2018 national standard limit value, T1 treatment lettuce edible part heavy metal content in line with the GB2762-2022 national standard limit value, indicating that modified PG land making use of the ratio under the feasibility, with the increase of modified PG ratio amount of the risk of heavy metal increases, T2 and T3 treatment lettuce edible part Pb content exceeded the GB2762-2022 national standard limit value, after the evaluation of comprehensive pollution index, T3 treatment soil is lightly polluted by lead. From the combined effect of PG land formation on lettuce growth and development and safety evaluation, the addition of PG land formation treatment with 50% of dry mass as the main raw material of PG is the treatment that achieves the maximum amount of PG elimination and safety for agricultural products in this experiment.