[vron]

Hi everyone just been looking at the Marshall catalogue, specifically their super fertilisers.

And was rather shocked by the very high NPK levels.

EG: Potatoes 14.14.21.  Brassicas 27.6.6.  Onion/Garlic/Shallots 12.11.18 and Peas/Beans 11.11.17.

Aren't these rather high especially the first two or are these levels ok.

I use growmore for my spuds and brassicas.  BFB for the leeks, garlic and onions and chicken manure pellets when needed.

Any thoughts

[JayG]

A 10-10-10 fertiliser has the same balance of nutrients as a 20-20-20 fertiliser but is only half as concentrated, so if the price per ounce/gram is the same for each the first one will cost you twice as much to produce the same effect.

As to the actual NPK ratios, I guess some might think the one for brassicas is slightly overdoing the nitrogen, even though they are leafy plants which need plenty of it. 

Having said that, I mostly use Growmore and dried chicken poo for the majority of crops, although even they can cause problems with foxes (BFB is a definite no-no here, and my last few tubs of Growmore unaccountably smell rather 'pooey'!)

As for carefully weighing out the quantities, it's the approximate handful to a square metre jobby for me, as and when I think a crop might need it on my sandy soil (moi, scientific? Only in theory!  )

[mumofstig]

They're ok as specific fertilisers - you are more used to seeing the lower ratios quoted for growmore - 7:7:7

which could also be expessed as 14:14:14 or even 21:21:21. in other words equal quantities of each.

Potatoes need more K in the mix whereas Brassicas need more n.

[Kristen]

Slow release fertilisers seem to have high NPK figures - presumably because the actual nutrients are released over some period of time.

[beesrus]

I always steer clear of anything that appears to have some sort of overly concentrated or refining methodology behind it .... well, apart from the diesel I put in my van. What I really want is normal NPK levels in large amounts of vegetable matter. Anything prefixed with "super" gets a wide berth.
Just like our food, where we now know refined sugars for example are not a great idea without it's naturally occuring fibre, I tend to assume the same applies to our soil, if we are interested in it's health over many years.

Chicken manure pellets are the "strongest" NPK per kilo I use, they're my goto nuclear option, and really don't need anything stronger.

[mumofstig]

Each to their own, beesrus 

[beesrus]

Each to their own, beesrus 

Absolutely MOS, no problem with that. If someone wants to eat a bag of sugar with their breakfast, that's fine by me. They'll probably get more work done than I. 

[cadalot]

I'm using Coffee Grounds: 2.0/0.36/0.67 in my compost, the worms are going mad for it and snail & slugs don't like them at all

For a list of NPK for everything see http://www.lundproduce.com/N-P-K-Value-of-Everything.html

[Salmo]

Hi everyone just been looking at the Marshall catalogue, specifically their super fertilisers.

And was rather shocked by the very high NPK levels.

EG: Potatoes 14.14.21.  Brassicas 27.6.6.  Onion/Garlic/Shallots 12.11.18 and Peas/Beans 11.11.17.

Aren't these rather high especially the first two or are these levels ok.

I use growmore for my spuds and brassicas.  BFB for the leeks, garlic and onions and chicken manure pellets when needed.

Any thoughts

Fertilisers with these concentrations are what is used commercially. Looking at the Marshalls ratios there is little difference between that for potatoes, onions or peas/beans. Would you buy a different bag for each?

Growmore at 7:7:7 is OK as a general fertiliser. Just apply extra potash or extra nitrogen as needed for different crops.

The problem with chicken manure is that the ratio of nitrogen is too high for most crops, ok for brassicas. Leaf growth is good but always keep in mind whether your aim is leaves,  flowers or roots.

All this presumes that your soil is average and without doing a soil test you will not know. Old allotment soil and old gardens usually have plenty of everything and it is just a matter of topping up each year.

As a rule of thumb, clay soils have plenty of potash and are short of phosphate and light sandy soils have plenty of phosphate and are short of potash. Most soils are somewhere in between.

[beesrus]

What I think I was trying to put over is, just as some unthinkingly overdo the slug pellet thing to a massive, almost dangerous degree, it's also all too easy to overdo the fertiliser with rich mixes, especially in greenhouse pots. Farmers won't because they know what they're doing, but many people don't know that high Summer veg like peppers, sweet corn, beans etc won't thank us for over feeding. Too much can actually cause water issues, wilting, burning etc.
I think a lot of folk assume you can't have too much of a good thing.

[Robster]

I completely understand where Beesrus is coming from.  Its exactly the same with washing liquid.  You are encouraged to buy "super concentrate" because its more efficient and you only need 10 mls per wash, but the measuring cap is 20 mls which the company is relying on people filling up.  Therefore making it less efficient for the user and better value for the company.

So one handful of Growmore is one thing but a quarter handful of something else over the same area becomes more difficult and few do it precisely in the garden/allotment unlike farmers who do it very precisely.

[JayG]

I'm using Coffee Grounds: 2.0/0.36/0.67 in my compost, the worms are going mad for it and snail & slugs don't like them at all.

Do you think the worms might not be able to sleep, and are thereby keeping the slugs and snails awake too? I wouldn't like it much either!

+ +

Makes sense to know your soil and the nutritional requirements of your crops before throwing handfuls of fertiliser (of any size) at them.

Despite doing all I could and believed was necessary, including using an annual dressing of Growmore or dried chicken poo and as much home-made compost as I could make, it still took several years before the penny dropped that sandy soils like mine lose most of their nutrients very quickly, even during the course of the growing season.

It's true that you do need to be careful with dry fertilisers though - I'm still kicking myself for almost killing my greenhouse tomatoes last year, not by overdosing the containers with Growmore as such, but by stupidly adding it in a single layer rather than mixing it in properly, which stunted their root development for months. 

[mumofstig]

It's not the fault of the product if we don't follow instructions, and therefore add too much, is it?

The question was - are the NPK levels ok?

Of course there may be reasons you chose not to use them, opting for something different/something more organic etc ................................... but the answer is, yes - the NPK levels are ok 

[vron]

Hi and thanks guys for all the info.

I was just shocked by what appeared to be such high concentrations of NPK.

You know how confusing it can be for those new to gardening, who think more is good?

We have no intention of changing our methods of feeding our crops.

We have had our present allotment since March 2006 (our previous lottie we had in the late 70's)
And we are still learning as we go along.

At least we can adjust feeding as and when required for those that need a little extra boost.

[Robster]

Actually yes it is the fault of the product if it is badly designed or deliberately designed in such a way as to encourage misuse.  Companies put an awful lot of effort into understanding how there products interact with human nature.  In a perfect world you would be absolutely right.  But it isn't perfect because there are humans in it.  But weather its a BOGOF a 50oz drink or an oversized washing liquid cap.  They are all designed to encourage additional unnecessary consumerism. Which generally encourage wastage and excess spending

Of course if super concentrated is precisely used per instruction its fine.  It could be 33:33:33 and it would be fine If there weren't humans