Fertilisation with Manure Causes Variability in the Soil of Urban Garden Plots

Urban and peri-urban agriculture (UA) plays an increasingly important role in pro-moting sustainable urban development, delivering socioeconomic, environmental, and educational benefits. However, UA is often associated with nutrient accumulation in soils, as vegetable-growing areas typically receive substantial inputs of organic and inorganic fertilizers. This study examines soil variability in two sections of an urban allotment garden subjected to long-term manure fertilisation for 12 or 16 years at ap-plication rates up to 10–12 kg m⁻² yr⁻¹. Surface soils were analysed for organic and in-organic carbon, total N, available P and K, pH, and elemental composition using port-able X-ray fluorescence (pXRF). Prolonged manure incorporation substantially in-creased soil fertility, evidenced by elevated soil organic carbon, total N, available K, and both total and available P. Marked shifts in mineral composition were also ob-served, including significant increases in total Ca, inorganic C (as calcium carbonate), Sr, and S. Despite the high manure inputs, no accumulation of potentially toxic ele-ments (PTEs) was detected. Nevertheless, pronounced heterogeneity was found among individual plots, reflecting differences in fertilisation intensity and management prac-tices. pXRF proved highly effective for identifying soil compositional changes and pre-dicting nutrient availability, highlighting its potential as a rapid diagnostic tool for precision agriculture management.