The spatial variability of macronutrient content was analyzed in an orange orchard (cv. "Pera Rio"), set up in a typic Hapludalf soil. The correlation between yield and fruit size was determined. The experimental area was located at Capitão Poço, in the eastern part of Amazonia region, Pará State. Leaf analysis was performed in 120 plants and the leaves of third and fouth branches were collected in all quadrants, totalizing 50 leaf samples for each plant. The soil was sampled at 0-20 cm depth below the crop canopy, in accordance to leaf sampling location. Leaf and soil data variability were measured with geoestatistics technique and the orchard areas of higher and lower variability were assessed. The yield maps and fruit size showed high spatial variability. The total fruit production ranged from 11.25 to 80.8 kg plant-1, the average fruit size varied with the plant row, probably because of hoeing in alternate plant rows. The fruit size varied from 42 to 78 mm. The orange yield was affected only by the number of fruits per tree.
geostatistics; macronutrients; precision agriculture
