Spatio-temporal change of soil pH, P2O5 and K2O content under variable mineral nitrogen fertilization

Soil sampling is the first step in generating field-specific information on which to base agricultural input decisions. The objective of the study was to evaluate spatial and temporal variability of soil pH, plant available phosphorus (P2O5) and potassium (K2O) content under variable mineral nitrogen (N) fertilization. The research was conducted on the experimental field within hydro-ameliorated cropland in the Western Pannonia subregion of Croatia (45°33’N, 16°31’E). Grid soil sampling (15x15 m ; n=200) was carried out with semi-automatic circular tractor soil probe at 30 cm depth after winter wheat harvest in 2010 and 2016 covering ten fertilization treatments (0-300 kg N ha-1). A sequence of spatial changes in soil properties was influenced by differences in N rates, liming, field drainage and specific terrain features, although similar spatial response was apparent for both investigated years. A two-way ANOVA revealed that only soil pH values significantly differed among two years (p