Post-fertilization changes in soil-macronutrients explored in three locations on intensively-cultivated soils in Ethiopia. Fifteen soil-samples before planting; and 30 after wheat-harvest were collected from middle-blocks at five-depth intervals, 120 cm deep-pitd. After harvest, samples were collected only from control; and full-dose Nitrogen-Phosphorus-Sulfur-Calcium (69:20:18:23 kg/ha respectively) treated-units. Results showed substantial-pool of (macronutrient contents up to 30%) remaining in topsoil after wheat-harvest. However, N and S which were already low in the initial topsoil went to severely-deficient level after harvest. But, the available-P was dramatically variable possibly due to previous applications in narrow-bands/small-spots. Calcium became excess in already Ca-rich calcareous-soils. Profile-wise, soil-pH, SO42-, CEC and Ca2+ increased with depth, while soil-OC, total-N and P followed reverse trends. Major contributors for such spatiotemporal-dynamics in soil-properties were conceived to be the rates of biomass-recycling; clay-mineralogy; soil-texture and pedogenic-processes like leaching. Correlation-matrix also showed wide-variations among soil-properties. Such soil-variability reflects the history of fertilizer-use/cropping-systems; and also the differences in soil-profile characteristics. The insights gained from this study indicate the significance of nutrients remaining after productive-crops in future soil-fertility planning. But, additional crop/soil specific nutrient-balance model experiments detailing the respective macronutrients at farm etc. levels can be installed. This will allow us making site-specific-cost-effective fertilizer recommendations.

Keywords: Post-fertilization, soil-profile, residual-nutrients, leaching-loss, nutrient-balance