Episode 201. First Principles Continued: Manures

This is the World Organic News for the week ending 3rd of  February 2020.

Jon Moore reporting!

Decarbonise the air, recarbonise the soil!

This week we are delving into the font of fertility: Manures.

The lifeblood  of organic production, manures keep your fertility ticking along. Fertility determines your production. Choosing which one to use can be fraught with complications.

What do the NPK numbers mean? Can I trust the figures provided? How do they relate to the seeds I’m using? How much sleep should I lose worrying about this?

Most of the manures I use do not come with an NPK rating. These stand for Nitrogen Phosphorus and Potassium. I mention them because I’ve seen a number of “organic” fertilizers with added chemicals available in a well known hardware supplier. The same is true for blood and bone fertilizers.

The science of all this has been predicated on the idea of commercial growers. Things like artificial fertiliser, hybrid seeds, pesticides, herbicides and irrigation. Maximum production from minimal area. This may make sense in some conditions but does not mimic Nature. 

The key to using good manures is to collect them from your own animals. I understand that isn’t always possible but there are options.

Horse Poo

There’s a place down the road from us where the people keep horses. They regularly have feed bags full of droppings for sale for $2.00. You may pay more where you are but these things are available. A word of caution though. Unless you can be sure of what’s gone into the front end of the horse you can’t be certain of what’s coming out the back end. That being said, hot composting the horse poo makes a big difference. I’m not sure about antibiotics or anything else that may or may not be fed to horses and the effects of composting on those so be careful.

In the end, the easiest way to decide which manure/manures to use usually comes down to two factors. (1) What you have on hand; and (2) What you can afford to purchase.

Nature has evolved with a tendency towards redundancies in systems.That being said, not knowing the actual chemical composition of the manures you use probably doesn’t matter that much. Given that you’ll probably be growing heirloom/heritage seeds, the bell curve of the genetics of the seeds will be much wider and somewhat shallower than extensively hybridised commercial seeds. These are developed to work best within a set of water, fertiliser and daylight parameters. We are growing better food than that so we can be a little more relaxed when it comes to inputs, as they say in the bean counting world.


There’s a table in the show notes with Nitrogen, Phosphorus, Potassium (NPK) and Calcium figures for some common organic manures. These are just guidelines. Don’t stake your financial future on them use them as a rough rule of thumb. 

The approach I take and advocate for you is: use what you have. If you keep chooks, use poultry manure, especially if its mixed with bedding. That bedding can straw, bracken, wood chips, wood shavings, even saw dust or leaves. If you let it rot a little and add it in Spring and Autumn/Fall it won’t have a detrimental effect.

Pick the right crop to add it to. Spuds love manures but not straight chook poo. Nothing much is keen on straight chook poo so you could toss it into your compost piles or mix it with vegetable waste and run it through your compost worms. 

By adding things once or twice a year, you get to make strategic decisions as to where and why you are adding manures. Feeding hungry plants is probably the best use of manures. As I said, spuds but also sweet corn or a maize crop of any sort would be a good start.

A word of caution. Once the wonders of manure become apparent to you, they become an obsession. Collecting the stuff from wherever you can find it. In the past I was known in some circles as the Poo King. Begging, borrowing and scavenging from anywhere, organic matter, leaves, straw, chipped wood and poo of all kinds become some of an all consuming passion. I didn’t stoop as low as dog and cat droppings. Cats can pass on viruses, I read somewhere so that’s probably best avoided. 

My preferred use of all these things, wood chips aside is as feed for compost worms. I find the worm casting are rocket fuel. 

Otherwise manures can used under the cardboard sheets/newspapers used when setting up a no-dig bed as described in Episode 198. Here it is away from the sun and in contact with the soil where the soil biology can get at it. 

This is a good use for just manures or even when they are mixed with straw, as in animal bedding. The bedding can be used directly as the organic matter in the beds. It is worth noting E coli can be found in this material and the straight manures too. Be careful, wash your hands after handling and wash produce before eating.

Of course fully heat composted material doesn’t have this issue and I can’t say I’ve ever had an issue but be aware.

Basically, find your poo source, handle it safely and grow great food!

Now if you’ve made it this far in the episode, I’m assuming you have an interest in what I’ve been talking about, both today and the last few episodes of this “First Principles” run of shows. So if you’re ready to put these things into practice, pop over to WorldOrganicNews.com, drop your email and first name into form on the front page to get a hold of my No-Dig Gardening Book for nix. The techniques and examples there will  help you to feed yourself and your loved ones and:

Decarbonise the air, recarbonise the soil!

Thank you all for listening and I’ll be back next week.

Percentage Values of Organic Fertilizers *

Type Nitrogen Phosphorus Potassium Calcium
Average Farm Yard Manure 0.64 0.23 0.32 nil
Pure Pig Dung 0.48 0.58 0.36 nil
Pure Cow Dung 0.44 0.12 0.04 nil
Compost 0.50 0.27 0.81 nil
Deep litter on peat 4.40 1.90 1.90 2.20
Deep Litter on straw 0.80 0.55 0.48 nil
Fresh Poultry Dung 1.66 0.91 0.48 nil
Fresh Pigeon Dung 5.84 2.10 1.77 nil

*Source: The Complete Book of Self Sufficiency By john Seymour 0 552 98051 X (1976) Corgi.



World Organic News

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