First geochemical insight into phosphorus (P) concentration, origin, and spatial distribution in the soils of the...

Phosphorus (P) is an essential nutrient and a key component for sustainable agriculture. However, limited research has addressed its geochemical distribution in Armenian soils. This is the first study aimed at investigating the spatial distribution patterns of P, its association with major elements (Fe, Mn, Al, Ca, and K), pH, and soil organic matter (SOM) and at identifying its potential sources in the soils of the Ararat Valley, one of Armenia's most important agricultural regions. P concentrations ranged from 493 to 1932 mg/kg, with a mean of 891 mg/kg, exceeding the global soil average by about 1.53 times. Elevated P levels were identified in areas adjacent to Yerevan, suggesting potential anthropogenic inputs from irrigation, sewage sludge, and aircraft deicing. Geostatistical analysis showed that P follows a log-normal distribution with relatively low variability across soil types. However, distinct spatial clusters were detected. Two dominant P sources were identified: mineralogical (associated with Al and Fe oxides) and organic (linked to SOM decomposition). Based on P distribution patterns and locations of spatial clusters, geochemical baselines were defined: 798 mg/kg for Low-Low clusters, 1876 mg/kg for High-High clusters, and 1270 mg/kg for intermediate areas. These results provide the first geochemical baseline for P in the Ararat Valley, supporting improved monitoring of soil quality and nutrient dynamics. The study findings highlight the need for site-specific fertilization strategies and integrated nutrient management approaches to optimize P use efficiency. Adapting soil management to site-specific conditions can improve crop yields and reduce environmental impacts.