SOIL CaCO[sub3] CONCENTRATION AFFECTS GROWTH OF YOUNG GRAPEFRUIT TREES ON SWINGLE CITRUMELO ROOTSTOCK

OBREZA, THOMAS A.

Abstract


Many south Florida flatwoods soils are underlain by calcium carbonate (CaCO[sub3]) rock, shell, or marl that can produce an alkaline root zone if mixed with the soil surface. Citrus rootstocks vary widely in their susceptibility to low Fe availability in high-pH soil. Young 'Flame' grapefruit trees (Citrus paradisi Macf.) on Swingle citrumelo rootstock (C. paradisi Macf. × Poncirus trifoliata [L.] Raf.) were planted in spring 1992, on 0.6 acres of land that contained calcareous soil in about one-fourth of the area. Trees grew well on soils with no CaCO[sub3] in the root zone, but poorly on soils that had visible rock on the soil surface. Where there was no free CaCO[sub3], soil pH ranged between 5 and 7. As soil CaCO[sub3] concentration increased from 0.2 to 0.6%, pH increased from 7.1 to 7.9, and above 0.6%, pH was above 8. As CaCO[sub3] in non-ground soil increased from 0 to 1.6%, leaf N concentration of 2-yr-old trees decreased from 2.4 to 1.8%, and canopy volume of 3-yr-old trees decreased from 600 to 200 ft³. Grinding the soil did not improve correlation between tree growth and CaCO[sub3] concentration. CaCO[sub3] level did not affect leaf Fe concentration. Trees growing in acidic vs. calcareous soil had mean fruit yields of 60 vs. 10 lbs/tree, respectively. Yield dropped immediately when CaCO[sub3] was present, regardless of concentration. The high pH condition prevented Swingle citrumelo rootstock from performing to potential, making it more advantageous for citrus growers to plant rootstocks more tolerant of high pH conditions in these areas.

Keywords


citrus paradisi; limerock; calcareous soil

Full Text:

PDF

Refbacks

  • There are currently no refbacks.


Proc. Fla. State Hort. Soc.     ISSN 0886-7283