[Arid_gardener] Fertilizing citrus

[Olin Miller]

I'm not Dick but may I suggest you take a look at the fertilizer chart at

http://home.att.net/~millero/VSG/MC91-FertilizingCitrusChart.pdf

This is the schedule recommended by The Maricopa County Extension for home
grown citrus.  It is the same chart that appears on page 7 of the handy
booklet "Master Gardener Journal: Special Supplement - CITRUS" described at

http://cals.arizona.edu/maricopa/garden/html/pubs/mgpress/citrus.htm

Your tree would fall in the category described in Example 1 following the
chart, e. g.:

"EXAMPLE 1: You have a young tree, planted one year ago and a bag of
ammonium sulfate (21-0-0) that has 21 percent nitrogen. Find the row for a
young tree. Find the column for 21 percent nitrogen. They meet at the number
1.25 lbs. Therefore, apply 1.25 lbs. ammonium sulfate during the year. Apply
one-third of that amount (about 0.4 lbs.) during Jan-Feb, one-third in.
Apr-May, and one-third in Aug-Sep."  I don't know how much this is in terms
of kitchen utensils but it's about 6 to 7 ounces on a postage scale.

You may hear about monthly  fertilization schedules recommended for
commercial citrus orchards where the trees are being pushed to maximize
production.  But from Note 4 following the fertilizer chart:

" Give one-third of the yearly total of fertilizer during January-February,
one-third during April-May, and one-third during August-September. (This is
to prevent loss of nitrogen from the root zone and environmental concerns
regarding the leaching of nitrates into groundwater.)'

Native Arizona soils are typically very low in Nitrogen which is an
essential nutrient required by citrus.  Phosphorous is also required for
good root growth and for blossom and fruit development and is present in the
soil but will be depleted as it is taken up by the tree.  Potassium, which
is needed for the general health of the tree, is abundant in our AZ soil in
a form readily available to the tree and rarely needs to be added.  Ammonium
Sulfate (21-0-0 or sometimes 21-0-0-24S) is a  good fertilizer to use
initially because of the high nitrogen content (21%) and sulfur (24%) which
helps reduce the alkalinity of the soil.  But if you only have one tree you
night want to consider using one of the citrus fertilizers "developed for
Arizona soils".  These are bit more expensive but help to compensate for the
loss of essential and micro nutrients and trace elements as the tree grows

Olin Miller, Master Gardener Volunteer, Maricopa County AZ
http://home.att.net/~millero/VSG/desert_gardening/
==========================================

----- Original Message ----- From: "Clair Spackman" <cjspackman at ucdavis.edu>
To: <arid_gardener at CALS.arizona.edu>; "Dick Gross" <rkgross3 at cox.net>
Sent: Thursday, January 04, 2007 12:16 PM
Subject: [Arid_gardener] Fertilizing citrus


> Hi Dick,
>
> I was just thinking I need to look into fertilizing my new orange tree and
> was reading your last informative post. In it you state that "You should
> apply 1/3rd the tree's annual requirement in February, June and
> September." How do i know my tree's requirement at any given time I assume
> its size related?  It was planted last fall and was in a 29 inch box so
> its about 4feet high and about 3ft wide right now.