Evaluation of Cyperus Fertility Improvement in Aeolian Soils from an Application of Humic Acid Combined with Compound Fertilizer

Abstract

Humic acid is a macromolecular organic compound with active groups that, when applied to the soil, can regulate the storage and release of nutrient elements. The effects of a humic acid application at two application rates (F-1: 15 t·hm−2 and F-2: 30 t·hm−2) on soil physicochemical properties and plant growth and yield were compared in field experiments to explore the impact of the humic acid dosage on the soil fertility of aeolian sandy soils. The CEC, EC, pH, organic matter, and available nutrient content were measured in the 0~20 cm and 20~40 cm soil before and after the humic acid application. The results showed that the soil organic matter and available nutrient content increased significantly with an increased humic acid application rate. In the 0~20 cm soil layer, the contents of soil alkaline-hydrolyzable nitrogen, available potassium, and organic matter were the highest in the F-2 treatment, at 24.97, 207.66 mg·kg−1, and 8.99 g·kg−1, respectively, which increased by 76%, 66%, and 54% compared with the control treatment. On the other hand, the content of available phosphorus was the highest in the F-1 treatment, at 13.23 mg·kg−1, which was 38% higher than the control. In the 20~40 cm soil layer, the contents of soil alkaline-hydrolyzable nitrogen, available phosphorus, and available potassium were the highest after the F-2 treatment, at 16.33, 8.51, and 17.14 mg·kg−1, respectively, which increased by 19%, 113%, and 58% compared with the control. The organic matter content was the highest in the F-1 treatment, at 7.61 g·kg−1. After the humic acid application, the CEC and EC increased significantly, and the pH decreased. In addition, the growth status (leaf length, tillering number, and chlorophyll content) and yield of the Cyperus plants significantly increased with an increase in the humic acid dosage. In short, adding humic acid can effectively improve the physical and chemical properties of aeolian soils, regulate the nutrient circulation in the soil, and increase the yield and income from Cyperus cultivation.