AGROCHEMICAL SOIL MONITORING IN A MIXED ORCHARD: BASELINE–TO–FIVE-YEAR CHANGE AND IMPLICATIONS FOR FERTILITY MANAGEMENT

Abstract

Agrochemical soil monitoring represents the foundation for rational nutrient management in perennial fruit systems. This study documents fertility changes over a five-year interval (2019–2024) in a 2.2 ha mixed orchard located at the Rusciori Teaching and Experimental Farm (Sibiu County, Romania). Soil sampling followed the national agrochemical cartography methodology, using a composite baseline soil sample (approximately 30 subsamples homogenized) and additional row-level composite samples to evaluate both overall soil status and species-related variation. Initial baseline results (2019) showed moderately acidic soil, critically low nitrogen and phosphorus availability, and very high mobile potassium (440 ppm K2O). After five years, improvements in humus, nitrogen, and phosphorus levels were observed, while mobile potassium decreased markedly to 219 ppm K2O, identifying potassium as the dominant emerging limiting factor. These findings highlight the importance of periodic soil diagnostics in orchard systems and support species-adapted potassium management strategies, particularly on clay-loam soils prone to K fixation and extraction-driven depletion.