Rain flushing fertilizer?

20 years ago

Last week I fertilzied all my citrus..2 days later we had rain galore. Does this mean the soil was flushed and it was a waste of time fertilizing? Thanks, Toni

Featured Answer

malcolm_manners

20 years ago

Lots to consider when answering your question!

First, the micronutrients and phosphorus won't leach much in most soils, so the real concern with leaching is N and K.

If your soil is predominantly clay, or even if it has a high organic content, K won't do much leaching either (it's a severe problem in our sandy, low c.e.c. soils). So unless you're growing on sand, N is the problem here.

N: most often applied in one of 4 forms:

1. Urea. Cheapest, but rather slow to become available, and VERY highly leachable, in most soils. Once in the soil, it has to be converted by bacteria to ammonium (NH4+). Then depending on soil temperature and pH, it MAY be further converted (by other bacteria) to nitrate (NO3-). It is not wise to use urea during those times of the year when heavy rains are to be expected.

EXCEPTION: urea is often coated with something, such as sulfur or a polymer resin (osmocote, nutrikote, etc.), in which case it is protected from leaching.

2. Ammonium (NH4+). This form is much less leachable than urea, especially in high C.E.C. soils (clays and organic). In very sandy soils, though, it will leach away. Immediately available to plant roots, so if it has had a few days in the soil, your trees likely got much of it.

3. Nitrate (NO3-). The most quickly available to plants, absorbed very rapidly. BUT also highly leachable, so you hope for no hard rain for a week or two after application.

4. Insoluble organic N (sludge, tankage, etc.) is not leachable since it is not water-soluble. And it biodegrades slowly, over a period of weeks, to release ammonium a bit at a time.

In Florida commercial citrus, the current BMP guidelines say not to fertilize at all, June 1 to September 1. We want to apply 2/3 of the year's supply before June 1 (beginning around mid-February), and the remaining third after Sept. 1. But realize that nearly our entire commercial acreage is on highly leachable soils, and that our rainfall is higher than in most of the rest of the country (70" here, last year, and 4.5" since yesterday).

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Comments (10)

citrusboy
20 years ago
Hi Toni,

Can't find anything on the absorbtion rate for fertilizer in the soil. I did find information that said that foliar (Leaf Spray) fertilizing is absorbed almost immediately. But you are talking about soil based fertilizer, I'm sure.

I will keep looking...

Citrusboy.
birdsnblooms
Original Author
20 years ago
Thanks Citrus..No, the citrus weren't foliar fed but done in the soil.

Citrus, how ofen do you feed your trees and what type of food do you use? You don't have to name the brand if you don't want, but let's say you used a Citrus food that said, good for 3 months..Would you use alternate foods in-between or wait? This concept confuses me.
My citrus books talk about feeding citrus 3-4 times a yr, but I've seen ppl talk about feeding monthly. Should I be feeding more? Thanks, Toni
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citrusboy
20 years ago
Hi Toni,

I use Vigoro citrus & avocado fert which has macro and micro nutrients. I have been using it on my in ground every 3 months for a couple of years. Trees seem to like it. I am much to lazy to make my own.

I just put my second application on my container citrus, which all seem to be doing well (Keep in mind they are all less than a year old at this location). Label states "apply as new spring growth begins and again at 90 day intervals, feeding 3 times during growing season." That's what I am follwing and nothing has died yet... Everyone seems to have their own regime. Kind of like asking someone for a cure for the hiccups...

I would call your fert company if it's an off the shelf brand.

Citrusboy aka Marc
birdsnblooms
Original Author
20 years ago
Marc, I only bought one citrus fertilzier at a local store, but the others are from online stores.
I'm still confused why some ppl feed once every 3 months like u and others feed several times a year..lol..Toni
bencelest
20 years ago
Toni:
Since it is summer I feed mine every time I water. I am using the miracle grow 30-10-10 with micros and it says on the label feed every 7 days. That's what I'm doing. Just follow the Instruction and you can't be wrong. But let's say, feed every 3 months on long lasting. Usually when the tempt gets higher and you water your citrus more often the breakdown of that long lasting will not last 3 months. Maybe 2 but not 3 so you have to supplement more.
Just do at what you think is right.
That's what I do. Play it by ear.
When I see my plants need some more I fertilize more.
birdsnblooms
Original Author
20 years ago
Ben, you made a very good point about more water in summer and fertilizer..I never thought of it that way. So, MG is the only fertilizer you use? I thought you mentioned using a 3 month citrus fertilizer before..Maybe not..Toni
bencelest
20 years ago
Toni:
I changed fertilizer like I changed girlfriends (LOL) .
No, no.no. Just kidding. I am not like my son who is 14 years old and he changed 3 gFs in a month.
No, kidding, when I go to the store I usually go to the fertilizer department and see which one is the cheapest for the most bucks and of course with micros added. Once I found what I want I buy a whole lot.
Yes I used to use those Vigoro's long lasting but I am out now for quiet a while.
birdsnblooms
Original Author
20 years ago
Ben, you ladies man, you..LOL, j/k..I know what u mean about your son having 3 g/f's per month..that goes on here, too..lol w/my son.
When u used Vigoro, did you add other fertilizers? I could have sworn you did..I don't want to overdo it..u know?
I lost my two Etrons this winter..I give up on them. Everything else is doing fine, but we need warmer weather. It's only 78or so..CAn't wait till it's 90 again..Next wk..they're predicting anyway.
birdsnblooms
Original Author
20 years ago
MM, According to the container the fertilizer has 3% Ammonium and 27% Urea. Darn. Maybe I'd best stick w/the citrus fertilizer. I have 4 brands..I'll have to check the N on the others.
MM, the continuous rain was a fluke..we usually get a lot of rain from Mar-May w/an occassional summer storm. It was unexpected. If I'd known I'd have waited until the rain ended. Thanks for the info..Toni