Fertilizers major and minor elements

[Gareth]

In a recent discussion on the subject of using 100% diatomite Paul asked about some of the fertilizers i was using and commented on the breakdown of some various fertilizers i was using and what he thought of them.

I am using

- seasol seaweed concentrate for soil conditioning
- seasol powerfeed for a liquid fert
- Yates Kickalong organic complete garden used in the potting mix and periodic addition to the top of the pot for extra fertilizing
- composted chicken manure for the same application as the kickalong
- osmocote tree and shurb slow release for trace element and slow release direct to the plant

but this got me thinking, if im using the power-feed and the Kickalong would i really need the osmocote, and is all that is needed is a simple trace element supplement like the following

http://www.azomite.com/

my questions are, what are peoples thoughts on fertilizing programs in general, the above is only for general plants, and this would have to change for natives and other plants, so anyone opinions on individual plant species as well would be good.

This may help us compile a fertilizing program for general plant groups to achieve the best growth for our plants.

has anyone used the azomite product and how did they find it?

i think sometimes we over complicate fertilizing programs, people seem to get good results with the power-feed liquid fertilizer, and seasol is a clear winner in everyone's book (almost), but i don't believe this alone is enough, but perhaps some of us (and even myself included) may be using far too many fertilizers, providing the same thing, that may not only be a waste, but might actually be too much.

Everyone's experience and plant needs will be different depending on climate, species, potting medium etc but i think this is what a lot of people are looking for, a guide for these different applications.

Gareth

[Jamie]

gday man

great topic! i actually think a lot of people under feed trees, i know i have a heavy fert program compared to others, but my trees are all healthy and all grow strongly.

what i do is every 6-12 months is give my trees a couple of doses of a complete trace element fert over a couple of weeks, generally this repleneshes anything that my normal fert regime doesnt have. even though most ferts have some trace elements. i keep it pretty simple though i dont stick to just one liquid fert, i get whatever is cheap at the time and a change of fert is nearly like a holiday for the trees.

i have used the seasol powerfeed and found that good. also thrive, fish emulsion, aquasol and various others. i always have seasol and use that regularly, and ontop of that superthrive. also in with my medium is a slow release fert, ontop of the medium is DL and some added slow release aswell.

as for specific trees and ferts my grow on trees get that treatment, my trees in pots dont get as much, the DL is generally not used, the slow release is, and the potted trees get the liquid ferts and seasol/ST at a usual weekly interval.

jamie

ps. sorry if that seemed a little scrambled, i was getting distracted by kids

[63pmp]

Gareth,

The problem with these discussions is that people do not state the rate of fertiliser used. If the dose is given then the actual amount of fertiliser added can be calculated from the analysis of the fertiliser. It’s great that people post up the stuff they use, but how much you use is the critical factor.

I’ve not used azomite, but it sounds plausible. The difference between soils and potting mixes may not make it so valuable, as it must be applied in a fine powder for the aluminosilicate structure to decompose. This will either glugg up the potting mix, or wash out with watering. The website you posted had a very interesting summation of the biological processes in plants that the varying nutrients are required for. Thanks for posting it.

A big problem with fertilizing is that each plant has its own needs at different times of the year, and NO ONE knows what the correct amount to feed the plant is. Throw in 13, or so, elements required for growth and you end up with an infinite variety of fertilising recipes. Plants require a certain level of each element, too little and the plant starves, too much and it leaches away, wasted. So a certain balance of elements is required, the problem, as stated, is no one knows what this balance is, it can only be achieved by conducting fertiliser pot trials on individual species in your microclimate.

However, to simplify it we can use what is called the Steiner ratios and theory. This was originally proposed for hydroponic solutions, and basically says that a plant will tolerate a wide range of element concentrations in a solution, but will require energy to do so. The closer the ratio of solutions approaches an ideal, the less energy the plant expends on gathering what it needs and so plant growth improves. Steiners nutrient ratios give us a baseline to start experimenting from. Steiner’s is only used for macro nutrients.

So as an example we can compare say Seasol Powerfeed with Steiners ratios and see what happens. Remembering that EC is also a factor in fertilising. Steiners has an EC of approx 400 uS/cm.

There are several assumptions to be made, firstly all the N is to be present as nitrate, this will of course be less in reality; and that the nutrients are available at the same time.

The dilution rate is 25ml of powerfeed in 9L of water, as described by the product. An example calculation. Powerfeed has 12% N w/v, (12g N/100ml) therefore 25ml of powerfeed will contain 3g N, or 3000 mg N. Dilute in 9L gives 3/9 g N /l = 0.333g N/l = 333mg/l = 333ppm N

so we get a table;

Edit - I try and make a table but it turns out like this, it needs expanding, so that there is 3 collumns, steiners Seasol and Handrek and Black standard hydroponics solution.
steiners are 60, 5, 35, 45, 20 and 35
seasol are 333, 36, 194, 5.6, 1.7, 4.2
H&B 70-200, 15-60, 200-400, 150-300, 25-60, 20-150
for N P K Ca Mg SO4


Atomic symbol Steiners Theoretical Seasol Powerfeed Handrek and Black
Hydroponic soln (ppm) Standard Hydroponic solution ranges (ppm)
25ml/9L
N- Nitrate 60 333 70-200
P 5 (as H2PO4) 36 15-60
K 35 194 200-400
Ca 45 5.6 150 – 300
Mg 20 1.7 25-60
SO4 35 4.2 20-150


So we can say that Powerfeed severely lacks calcium, magnesium and sulphate. This would need to be addressed somehow for maximum plant growth.
Now we can say that powerfeed is a manufactured product, I would say the manufacture has added Urea for N and dipottassium phosphate for K and P. The implications are that nitrate will be slow to appear, but K will leach quickly. I would use the solution 2 a week, adding a teaspoon of epsom salts to 9l of solution and sprinkling gypsum on the surface of the potting mix. THis would improve the balance of the fert. The next thing to look at would be pH changes over time

I hope this helps, its how I look at fertilisers and products.

[Gareth]

that is some good information, and makes a lot of sense.

does anyone else have anything else to add?

perhaps the concentration of the individual elements is looking into it a bit too much, what i was wondering was could certain fetritlizer types like those from my first post be supplying the same things? of course it all depends on the fertilizer type and source but what are peplles thoughts and experiences, i know it depends to some degree on the type and amount, but i believe the more information we can gather the better idea we will have.

gareth

[63pmp]

Gareth,

If you don't look at the individual elements and the concentrations that you are applying, how do you know what you are putting on? How do you know what elements are present or absent in your fert'n program? It is exactly for that reason the manufacturer puts the elemental analysis on the side of the pack.

Paul