Biostimulant-driven improvement in yield, seed quality, and soil health of peanut (Arachis hypogaea L.) cultivated in arid sandy environment

Two field experiments were conducted during the 2023 and 2024 summer seasons to evaluate the effects of commercial biostimulants on peanut (Arachis hypogaea L.) productivity and soil health under arid sandy soil conditions along the Alexandria Desert Road, Egypt. A randomized complete block design with four treatments control, Humic King (humic acid), Biofertile (microbial inoculant; Azospirillum brasilense and Bacillus megaterium), and Kelpak (seaweed extract) was implemented with three replicates. Biostimulant applications enhanced several agronomic and quality parameters compared with the control. Total dry weight increased by up to 10.2%, while pod yield improved from 1.93 to 1.99 t ha⁻¹ in the control to a maximum of 3.41 t ha⁻¹ under humic acid treatment. Harvest index increased significantly from approximately 30% in untreated plants to 35.7% under humic acid application (p ≤ 0.05). Seed oil content reached 43.2% under humic acid compared with 41.4% in the control, whereas seaweed extract increased seed protein content by up to 14.4%. Post-harvest soil analyses indicated improvements in organic matter, available nitrogen, and reductions in salinity-related parameters, particularly under humic acid and microbial treatments. Overall, Humic King demonstrated the most consistent agronomic and soil benefits, supporting its recommendation for peanut cultivation in nutrient-deficient sandy soils under arid conditions.