Are organic fertilisers better than inorganic ones? - I say no

An excellent general fertiliser - buy this analysis for general garden use

I bristled when I read on a fine technical North American gardening blog that ‘of course organic fertilisers were best’. I only cooled down when I realised that over there popular gardening culture allows bulky organic material and manure to be defined as fertiliser. New gardeners over here often make the same mistake.

My argument today is about fertilisers which are legally defined as ‘a concentrated source of nutrients’ Such fertilisers might be either inorganic or organic Organic ones are derived from plant or animal sources - although in this mad world we live in, certain so called ‘natural’ inorganics are honorary organics too! 

Bulky manures such as farmyard manure also contain nutrients - even enough nutrients if used wisely to provide for most gardening needs. Such bulky organics do much more than merely provide nutrition and are excluded from my arguments today.

A few fertilisers defy precise definition and such materials as chicken droppings by virtue of concentration are best thought of as a fertiliser rather than as a manure.

Best treated as a nitrogen fertiliser (or for me not used at all)

It’s not my purpose today to decry organics (although for many I actually do). My aim is to explain why when I look to feeding my plants I personally always use inorganic fertiliser. Somehow gardeners have got the false notion that organics in some way are more worthy. There are no general grounds whether environmental, or of efficiency, precision, hazard, cost, safety, plant and soil health, crop quality, taste or yield where I agree that organics are better. Not even smell.

My tomatoes are high yielding, nutritious and tasty

There are of course individual exceptions. Some organics are excellent for specific needs and some inorganics (such as rock dust) are useless and some if misused might kill your plants.

Gardeners need very few different fertilisers. I suggest three. That would be a balanced nutrient general fertiliser, a slow release one  - only if they make up their own potting composts - and a good general liquid feed such as one sold for tomatoes. Some soils will benefit from lime and personally my own lawn enjoys iron sulphate.

I sometimes use lime

Yaramila

I have been using these blue granules for ten years now

I have argued before that you need just one general granular fertiliser. I use yaramila. There are others its equal but it is the right one for me. It holds all the six major plant nutrients (with NPK in fairly even proportion) and most of the trace elements. Your soil might not be deficient in trace elements, lucky you, but are you sure? The plant will take up the nutrients it needs and most of the remainder will enrich your soil and benefit future crops.

You won’t find yaramila at amateur gardening suppliers but it is readily available on the net or from a trade horticultural supplier. It comes in 25kg bags. You get the price benefit of scale when you buy such a big bag and for the average gardener it will last several  years - or you can split a bag with friends. My own last purchase cost £22. It is a hard nutrient prill that stays dry in storage.It is soluble and will quickly benefit your plants. It is not sufficiently soluble for conventional liquid feeding.

I illustrate my case today with how I use my yaramila. No organics for me do the job so well.

• Most of my vegetables get a top dressing (scattering on surface), very little for some and rather more for brassicas. By careful placement I avoid contact with young plants.
• I don’t generally use any fertiliser at all in my ornamental borders but it is becoming apparent on my very sandy soil that certain plants benefit hugely. With fertiliser my Cyclamen coum, monarda, rhododendrons do so much better and hungry delphiniums thrive. 
• Outside tubs are subject to leaching and I top dress as appropriate

I was a little heavy handed with my recent annual application to my hippeastrum (at present inside the conservatory)

• My house plants are top dressed too. Personally I find it more  convenient and just as good as liquid feeding. Even our orchids are so much better for a dozen granules every two months.

Brenda’s orchids have never done better

• It works out so much cheaper to feed my lawn and I don’t need to restrict myself with wretched ‘three in one’
• I make an early February application to my Autumn raspberries, rhubarb and asparagus
• My National collection of dicentra is top dressed either in the ground or in pots

I grow my Dicentra cucullaria outside in litre pots. They are top dressed in September and February

• When making up composts for lusty large plants such as tomatoes I use yaramila sparingly as a fertiliser base dressing. (I can top dress with more later). Never for delicate seed or seedlings - it is harmfully soluble. Not one for beginners! My scientist friend Peter recently made up a soil based compost using yaramila at 1 gram per litre which he calculates to be the same strength as a ‘medium’ commercial compost.. 
• The complete analysis of yaramila  makes it particularly suitable for the nutrient charging  of my homemade charcoal which I am now using as a seed and potting compost.

A word about slow release fertiliser

Ideal in making up potting compost

Although some organics such as hoof and horn meal were the bedrock of a slow release source of nitrogen in old formulations of John Innes composts it has now been superseded by the coated inorganics. Variously described as timed release or programmed release they give up their nutrients in a very gentle way and as nutrient diffusion is temperature related give up their goodness when the plants most need it. In tubs, pots and baskets their gradual release of nutrients reduce leaching. Coated fertilisers have various analyses and you can choose one supplying all the major nutrients and trace elements. They are not cheap!

Are not all the rugby and soccer pitches on the television so healthy, green and magnificent right through the Winter these days? I wonder how many are using slow release inorganic fertiliser.

As stated yaramila is not slow or controlled release. I have previously used coated slow release when making up my potting compost as does plant propagator friend Peter but with my current methods I don’t.

Growmore is an excellent (but weaker) inorganic general fertiliser for amateurs but only contains NPK

I am not very keen on single nutrient fertilisers but this nitrogen fertiliser will certainly green up your lawn at 30g per square metre

Links

I have not given any evidence today why I actually think organic fertilisers such as blood, fish and bone, fishmeal, chicken droppings, seaweed extracts  are inferior to inorganic but In the past I have explained why I scorn bonemeal.

My previous efforts on fertilisers supplement this post. I made a case for yaramila here - and say more why I consider the use of special fertilisers for particular plants is usually a rip off.

I discuss using fertiliser in Winter.

I recommend using a general fertiliser on lawns

I have argued that proper use of fertilisers might improve soil structure and can be used to build up the fertility of a soil.

I describe how I charge up my charcoal with nutrient

I attempt to puncture the modern myth of rock dust as a nutrient source.