Mineral Nutrition Status of Valencia 0r''.-


 The present recommendation by the Citrus Experiment Sta-
 tion for nitrogen (12) is 0.4 pound for every box of oranges pro-
 duced. The fact that the majority of the growers used 0.5
 pound or more nitrogen per box of fruit produced would seem
 to indicate that most of the growers either anticipated a much
 higher yield when the fertilizer was applied or believed that the
 recommendation was too low. The subnormal rainfall in 1954
 and 1955 undoubtedly affected the fruit production in many
 groves, but it must be recognized that many growers are using
 more nitrogen than recommended. Whether the slight increase
 in yield associated with the additional use of nitrogen can com-
 pensate for the extra cost would be determined largely by the
 relative market price of fruit and the cost of nitrogen.
 There was no consistent trend between fruit production and
the various quantities of phosphorus applied in the fertilizer.
Phosphorus applications tend to accumulate in these soils and,
as a result, a considerable reserve has been built up in many
groves through fertilizer programs over the years (5,9,28).
Use of additional phosphatic fertilizer has not been shown to
serve any useful purpose.
 Variations in the quantities of potassium and magnesium
involved in this study had no detectable effects on fruit produc-
tion. Results from controlled experiments with phosphorus, po-
tassium and magnesium (15, 19, 22) indicated that these ele-
ments have little influence on fruit production, except when
trees are markedly deficient. Most of the groves under study
were in the sufficient range from the nutritional point of view.
As a result, the effects of these elements, if any, cannot be dem-
onstrated in the relatively narrow range covered in the study.
 Fruit Qualities.-Very few fruit quality characteristics were
related to the rates of different mineral elements applied. It
will be pointed out in subsequent discussions that fruit quality
is much more closely related to the mineral composition of fruit
than to fertilizer treatments. Only those characteristics of
fruit quality showing statistical significance in relation to fer-
tilizer practices were included in Tables 15 and 16.
 The percentage of fruit smooth at stem end, a measure of
rind texture, was inversely proportional to the quantity of nitro-
gen applied. No other relation was found between fruit quality
and the nitrogen applied. No significant difference was observed
in fruit quality that could be attributed to the quantity of phos-
phorus or water-soluble magnesium applied.