Study on the Adsorption and Leaching Characteristics of Boron Fertilizer in Different Types of Soils

【Objective】Boron is an indispensable trace element in plants. Investigating the leaching and adsorption behaviors of boron in various soil types is profoundly significant for guiding the application and management of boron fertilizers in agricultural practices within tropical regions.【Method】In this study, two typical representative soils of basalt and granite in Hainan were selected as the objects. Through indoor soil column simulation experiments, the adsorption and leaching change laws of different forms of boron fertilizers in the hot zone soil were analyzed.【Result】As the number of leaching times increased, the pH value of the leaching solution generally showed a trend of initial rise, followed by a decline and eventual stabilization. Specifically, the pH values of basalt and granite soils after leaching increased by 0.49 and decreased by 0.51, respectively. The electrical conductivity (EC) of the leaching solution initially rose and subsequently decreased with the progression of leaching times. Moreover, the dynamic patterns of EC change in various boron fertilizer treatments for both soil types were largely similar. After leaching, EC in basalt and granite soils increased by 5.53 times and 6.52 times respectively. Regarding the boron concentration in the leaching solution, the BPP and E-67 treatments exhibited higher levels in the early stages, whereas the GC and GU treatments showed elevated levels in the later stages. The maximum and minimum values of cumulative leaching loss of boron in basalt were GC 2.76 mg/kg and GU 1.67 mg/kg respectively, while those in granite were E-67 3.70 mg/kg and GU 2.71 mg/kg respectively. Moreover, the leaching loss of boron in basalt was less than that in granite.【Conclusion】The application of boron fertilizer can effectively alleviate soil acidification, change the physical and chemical properties of the soil, and increase the boron content in the soil. Especially the slow-release boron fertilizer GU is more suitable for acidic soil in tropical acidic soil.