There is few knowledge of the localized fertigation effect (dripping and micro sprinklers irrigation) on nutrients distribution in tropical soils in a citrus orchard. The objective of this research was to evaluate the distribution of potassium (K+), calcium (Ca++), magnesium (Mg++) and phosphorus (P) in a tropical soil, under three water distribution patterns by localized irrigation method - micro sprinklers, single dripping line and double dripping lines per line of trees, and three irrigation depths -100%, 75% and 50% of the crop evapotranspiration (ETc) in an orange orchard. The sources of nutrients applied by fertigation were ammonium nitrate (N source), potassium chloride (K source) and phosphoric acid (P source) applied by fertigation parceled in 28 times. The results obtained showed that under the emitter, in the dripping treatments, there was depletion in Ca++ and Mg++ from the soil surface to 60 cm depth compared to prior levels to fertigation, whereas the P levels increased mainly in the 0 cm to 20 cm. In the micro sprinklers these effects were not observed, occurring more homogeneous distribution of these nutrients as in the transverse direction to the plant row as in the depth. The irrigation water applied by irrigation did not interfere the distribution of K+ applied by fertigation and Ca++ and Mg++ in the soil depth, but lower irrigation levels promote greater P concentrations in the most superficial layer of soil and larger water depths carry the P for deeper layers.
macronutrient; leaching; drip irrigation; micro sprinkler irrigation
