I have always thought that "Chemical" fertilizers are a cleaner and safer type of chemical to use than are "organic" chemicals. I would much rather have nitrogen from a bag on my tree than some animal's waste (manure & urine). But each to their own. In the final analysis, yes citrus can be grown organically, but as has been said, what the roots take up into the tree and into the fruit, is exactly the same nutrients - no difference- (chemicals) no matter which method your use. The "residues" in the tree and fruit that you are concerned about will be exactly -no difference- the same residues no matter which method of fertilization you use. About the temperature question you asked. For optimum growth keep your tree between 76-86F. At temperatures below 55F or above 95F the trees growth stops. I strive for 86F. Take care, and happy and successful growing by what ever method you decide. This has been an interesting post.- Millet

Hi Millet, "what chemicals" you ask? You don't really think I am calling NPK "chemicals" do you?

Even the newbie that I am know that NPK and Ca and Mg and other periodic table of elements are the nutrients. When I say chemicals, I'm referring to the other ingredients in the proprietary liquid formulas of each of these varying chemical fertilizers. I'm assuming there are some methyl's and some di-ethyls and other petro-chemical based ingredients, but since Miracle Grow doesn't list their ingredients on their website, I can't be sure what's exactly in it. However, I am assuming that the crazy blue fluid, the vehicle, so to speak, for getting those nutrients into the soil, has chemicals in there. That color does NOT occur in nature. LOL

Correct me if I'm wrong on this, but I'm assuming it's got chemicals. Colorants. Preservatives. Synthetic esters, etc. Those are the things I am most afraid of.

Then again, hey, maybe I've been too brainwashed here in the Bay Area, but I have been conditioned to question the chemicals on and in my food.

And just so you know, I'm not some troll hell-bent on changing your ways or proving the superiority of one approach over the other. I am just an honest newcomer to gardening and trying to understand the science of it better so I can make an informed choice for me and my family. I really DO appreciate all your answers as they shed more light on it for me. And I don't know that after a year of growing organically I might have a change of heart.

And, if someone were to tell me that there's a synthetic fertilizer that was JUST the nutrients and that it didn't contain added chemicals to make some branded proprietary magic-fluid, I'd probably jump on that.

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And thanks for the info on the temps. Is that for people growing their citrus indoors or in severe winter areas? 86 seems like a warm (and impossible) temp to maintain all yaer round for an outdoors pot.

Interesting websites, Skeet, thank you. In reading the first one, though, it brings back some of my organic chemistry lessons, and makes me wonder: when the "organic" form of N is not urea, but a more complex compound (as designated by R-C-NH2-COOH, where R is an undefined carbon string), the breakdown of the R string may lead to reduction products in the absense on enough O2, moisture, and may provide less attractive chemicals in the soil for organic growers than the fundamental chemicals provided in chemical fertilizers. Just a thought....Barbara

Phillip, commercial fertilizers used by most farmers do have a faster rate of runoff, but there is not enough organic fertilizer around, much less the cost and other pollutants associated with them to supply our major food crops with enought nutrients. All sources of N do have potential to eventually end up in our water as nitrate. When it comes to world wide sources of fixed N-- plants account for about as much as man (N - fixing plants).

As for other materials in commercial fertilizers, I don't know of any methyls or di-ethyls or such, If you read the link on manufacturing, you can see that N comes from AIR. Most granular commercial fertilizer is just N-P-K plus mineral fillers. There are some yard fertilizers that have pesticides, herbicides ect.

If you want a relatively pure source of N--use ammonium nitrate or urea. They do have impurities like everything--including organic sources, but they probably have less heavy metals and other impurities than "organic" sources.

Thanks for that link Skeeter... it helps me understand what they're doing and it actually makes the prospect of a synthetic fertilier more palatable to me. I will say, they were talking about the end result being bags of pelletized fertilizer that go direct to farmers in large feed bags. When I referred to the "proprietary mixes" I guess I am talking about the smaller, over the counter products at the big box stores that probably----but I don't have personal experience or evidence of this----have colorants and dyes and other things in them. Plus, I know they have some that are the combined pesticide/fert products.

And I just can't believe that the ingredients in MG are the same as the stuff on that website. How do you suppose they create that COLOR? LOL

Have a great day!

The color issue is very easy. A dye called Acid Blue #9, also sold under the name FD&C Blue-1 (FD&C stands for Food Drug & Cosmetics) is added to the fertilizer as a tracer. Greenhouses apply fertilizers to their crops through a machine called a 100-1 fertilizer injector, which is not located where the greenhouse crops are located. The actual employee fertilizing the greenhouse crop might be in an entirely different greenhouse. In order to be sure that the water that the employee is supplying contains fertilizer he relies on seeing the color. If the water has a blue tint then he knows that the crop is indeed being fertilized. Further the absence of blue also assures the employee that only water is being applied to the crop when they do not want or need to apply fertilizer. Getting back to Acid Blue #9 (FD&C Blue-1), this is the same dye one would be EATING when one eats a blue Popsicle, a blue sucker, blue jelly bean, blue candy add infinity. Lastly, 86F is a good temperature to grow citrus in order to obtain a high rate of growth. However, you certainly would NOT want to maintain this temperature all the time. During the fall and winter months, a citrus tree requires 600-850 hours of temperatures below 68F to obtain enough chill hours in order to produce fruit. If you grew a tree year around day and night at 86F, your tree would never fruit. Also a citrus tree appreciates a temperature differential of 10 - 15 degrees between day and night temperatures. - Millet (Drill ANWR)

I can buy Ammonium Nitrate for the farm with no one ever asking me any questions. Of course, I would not buy fertilizer from Home Depot. I would think that Home Depot would not want to carry Ammonium Nitrate anyway, as their customer base would not have a need for it. Home Depot's customers would purchase fertilizers intended for gardens and lawns. Something like 20-10-5. - Millet (Drill ANWR)

I can get ammonium nitrate at the farm stores around here, but they have to track buyers and they usually want to see my drivers license. I'm sure they know Millet where he buys it. I think the tracking requirement has run the cost up a bit and stopped some of the big box stores from carrying it.

Urea is another good source of N (45% N) if you can find it with low biuret. I recently bought a small 5# bag of Espoma urea--it did not have the level of buret impurity on the bag, but had a website where you could get the info or contact the company. It turns out their urea is a little high in biuret for use as a foliar spray on citrus--averaging 0.9% (0.7 to 1.2%), so I will be using it on the vegetable garden.

I don't know if organic farming groups consider it "organic" but technically urea is "organic".

Chemically speaking, any item containing the element Carbon (C) is "organic". - Millet (Drill ANWR)

"That reminds me of someone I used to work with that used herbs to cure everything because they were all "natural". Being the kind of person that likes to get people's dander up, I would often respond: "Poison Ivy is natural also, but I don't grind it up and make it into a tea"."

True! All the heavy metals are natural (Lead, Mercury, Arsenic ect)! Many of them even concentrate in the food chain making some organic fertilizers higher in some pollutants than commercial fertilizers. Heavy metals is the main reason that sewage is not used for fertilizer.

Human sewage is frequently used in agricultural fertilization. The city of Denver, delivers thousands (tens of thousands) of semi loads of human waste which is applied to Eastern Colorado wheat fields. Denver Sewage Department calls the " fertilizer" Metro-Gro. Denver even has their own huge injector tractors, and will inject the sludge directly from the semi trucks into the wheat fields. I have never used it, but I believe (not 100% sure) the farmer pays $5.00 per acre applied. It is said that the program helps the farmer and also helps Denver get rid of their sewage. The city of Milwaukee also sells human sludge fertilizer. Their product is even bagged, and is called Millorganite. Milorganite is heavily used on golf courses. Talking about natural heavy metals, every now and then when I eat an apple, I will chew the pulp portion of the apple seeds. What makes the apple seed have a slight sweet taste is Arsenic. - Millet (Drill ANWR)