Mineral Nutrition Status of Valencia Orange


 Soil analysis has been used to a limited extent in Florida for
 a number of years, on a routine basis, for the determination of
 phosphorus, calcium and magnesium as well as soil reaction. Re-
 sults of the present study indicated a good possibility of applying
 soil analyses together with leaf and fruit analyses in the study
 of mineral nutrition of citrus if sufficient research was conducted
 to correlate the analytical data with field conditions of response.

 SUMMARY AND CONCLUSIONS
 1. A survey of 168 commercial Valencia orange groves from
 the major citrus producing areas of Florida was undertaken in
 1955. The object of the survey was to study the mineral nutri-
 tion status of the groves in relation to fruit production and
 quality by means of foliage, fruit and soil analyses.
 2. All the trees were budded on rough lemon rootstock be-
 tween the ages of 14 and 47, with more than 85 percent of the
 trees between the ages of 16 and 35. By far the majority of
 the groves (80 percent) were situated on soils of Lakeland series.
 The number of trees planted to an acre ranged from 45 to 116,
 with 85 percent of the groves having between 48 and 73 trees
 per acre.
 3. Fruit production over a period of three years averaged
6.14 boxes per tree, covering a range from 2.45 to 10.48 boxes;
or 400 boxes per acre, with a range from 166 to 734 boxes.
 4. In general, most of the groves were adequately fertilized,
although both types and rates of material varied widely. Ni-
trogen was the only nutrient element under study that could be
directly related to fruit production, while phosphorus, potassium
and magnesium, in the amounts used, did not appear to be re-
lated to variations in fruit production. Correlations were found
between the nitrogen content of leaf and the nitrogen applied
in the fertilizer. Phosphorus application was related to phos-
phorus content of fruit and the available phosphorus in soil. Po-
tassium, when considered together with nitrogen, was signifi-
cantly correlated to the potassium content of leaf and fruit. The
fact that the water-soluble magnesium applied in the fertilizer
was not related to the magnesium content of leaf and fruit or
the extractable magnesium content of soil would suggest that it
was not the only source of magnesium. Evidence suggests that
dolomite is an important source of magnesium. The use of