Answer: Normally sweet oranges such a navel can taste sour if the trees are not watered regularly while the fruit is developing. All citrus trees should be watered often enough to keep the soil moist, but not soggy wet. Watering should be slow and thorough; probably every couple of weeks would suffice in any but the very sandy soils. As for feeding citrus trees, (both your orange and Meyer lemon), fertilize with about one cup of ammonium sulfate per year of tree age annually in split applications in February, May and September, i.e. a 6-year-old tree should receive about six cups of 21-0-0 spread out during the year.
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