SOIL HETEROGENEITY WITHIN A CITRUS GROVE IN SOUTHWEST FLORIDA FLATWOOD SOILS

Optimum productivity cannot be achieved if a citrus grove is managed as a single unit irrespective of variations in soil characteristics from place to place within the grove. The study was conducted in a 50-ha grapefruit (Citrusparadisi Macf.) grove in the 'flatwoods' of southwestern Florida and managed as a single unit although the grove contained six soil series and variable yields. The Pompano (Psammaquents) soil contained tall trees with high yields and the Oldsmar (Alaquods) soil had small trees with low yields. The objective of the study was to identify causal factors for the productivity differences. The Oldsmar soil was poorly drained and very acidic (pH 4.5-4.8) in the rooting zone. The Pompano surface soil of fill material was friable and better drained and the 0- to 90-cm depth of the profile was near neutrality, resulting in deeper root penetration. Traffic in the interrow zone increased compaction in both soils but compaction was not a causal factor for differences in tree size and yields. Problems in the low producing area could be corrected by adding tile lines at shallower depth to improve the drainage system and by applying lime to raise the soil pH.