Nutritional evaluation of citrus orchard under organic farming

Abstract

This study presents some preliminary results concerning the characterization and evaluation of the nutritional status of a or-ganic-grown orange grove (Citrus sinensis (L.) Osb. cv. Valencia Late) established on a calcareous soil in the south of Portugal (Tavira -Direcção Regional de Agricultura do Algarve).

Composite soil samples were collected at two depths (0-25 and 25-50cm) and various parameters were determined namely: texture, organic matter, extractable phosphorus and potassium, and total and active lime. During two years (2002 and 2003) the mineral composition of flowers (full bloom) and leaves between April and October was assessed. Total chlorophyll was estimated using a SPAD-502 apparatus.

The discussion of results was based on the mineral composition of leaves and flowers, which was compared with the values established for conventional agriculture. The applicability of a model for nutritional diagnosis established for citrus trees in conventional agriculture was tested in organic farming conditions.