Mineral Nutrition Status of Valencia Orange


TABLE 6.-THE DISTRIBUTION OF VALENCIA ORANGE GROVES BASED ON THE
QUANTITY OF NITROGEN AND POTASSIUM APPLIED (AVERAGE OF 3 YEARS).

Ratio Groves Distribution Average Quantity Applied
 Pounds per Tree Pounds per Acre
 N:K No. I N KO N K-0
 1:114 ..... 28 20.1 2.61 3.28 164 206
 1:1 .......... 37 26.6 3.39 3.37 230 229
 1:% ........ 13 9.4 3.28 2.90 234 210
 1: ........ 36 25.9 3.65 2.68 229 168
 1:% ....... 14 10.1 3.90 2.35 262 156
 1:% ........ 11 7.9 4.13 1.83 282 126


 The use of water-soluble magnesium in fertilizer covered a
range from zero to 2.91 pounds per tree, or 181 pounds per acre.
In 20 of the groves no water-soluble magnesium was used be-
tween 1953 and 1955. In general, growers calculate magnesium
rates on the basis of nitrogen applied. It varied between two-
thirds and one-half of the quantity of nitrogen used in the mixed
fertilizer. The distribution of groves using different quantities
of water-soluble magnesium together with nitrogen and phos-
phorus is summarized in Table 7.
 Minor elements were applied to the trees in fertilizers and in
nutritional sprays. The wide variations in rates that were
found among the major and secondary elements were not ob-
served with minor elements. With very few exceptions growers
followed closely the recommended rates (12). Manganese and
zinc were used in practically all groves. The use of copper in
regular fertilizer programs was found in only a few of the
younger groves. Annual application of 0.2 to 0.3 unit of borax
(as BOs3) was observed in about one-third of the groves under
study. The use of molybdenum in nutritional spray and iron
chelate as a soil application was not a part of the regular fertili-
zation program in most of the groves. Apparently these two
elements were used whenever the trees showed signs of need.
 The rate and frequency of liming was usually determined by
the results of soil pH measurement which were taken annually
in most of the groves. Liming materials were usually applied
either annually or biennially. In general, the rates were doubled
if applications were made every other year. In groves receiving
annual application of liming material, the rates of one-half to one
ton of dolomite or calcium limestone were most commonly used.