Soil Nutrition Part 1 of 3: Carbon, Nitrogen, Phosphorus & Potassium

(I would like to note that I am not a horticulturist but have simply compiled a lot or research and resources and wish to share what I have learned in hope it helps others.  As there is a lot of info and resources in this, I have broken this article into 3 pieces and will list all the resources at the end of  part 3)

I am always in the mood to educate myself about how my plants tick, but sadly sometimes lazy to write about it because of the time it takes.  I know though that if I don’t write about it, I’m never really going to remember and learn what I just ‘educated’ myself about.  So, I’ve dawdled for the past few months on this article about soil nutrients and know that I need to get things in gear for my sake and for content’s sake!

Soil nutrition is important for obvious reasons for the garden, and knowing what does what helps us better learn about our plants’ needs and how to make them thrive.

This will focus on organic gardening soil nutrition, rather than sterile “chemical elements do this and that” because even though it may be a fact that straight chemical fertilizers produce a desired effect on plants, it is my belief that beyond simple chemicals, organically improving your soil is essential for sustained upkeep of your garden/plants through conservation of the environment, building of soil mass, biodiversity of beneficial bacteria and slow uptake of nutrition for your plants.  Plus, it tends to be cheaper and that my friends is always a plus in my book!

(ADDENDUM: While soil nutrition is important, too much of a good thing is no good either.  Don't over do it! Too much nitrogen often occurs with straight chemical fertilizers and it runs off, which is bad for the ecosystem and for crops/plants because they become "fat and lazy" eventually as I call it.  Also, it can make for less flavorful crops, or more leafing rather than fruiting!  Thanks to vtlarica for point this out!)

Many gardeners are aware or at least have seen this N-P-K (nitrogen, phosphorus and potassium) formulas on bags of fertilizer or compost they purchase.  The levels are important to note if you have over or under abundance in any of the letters as these are the most important macro-nutrients that plants need for their most basic development and structure.  When you get down to it, plants are a whole heck of a lot of cellulose  (what gives the plant its structure) and chlorophyll (what makes the plants work and grow) and all these vital parts are composed of a lot of carbon and nitrogen.

As you have probably heard from all the environmental talk, there is a lot of carbon in the world (too much some say) so there's no real dearth of it.  Free-wheeling carbon in the atmosphere=not good but contained in the earth it’s great for plants and they have little trouble getting this element for their needs.  Carbon, in its organic rich physical form typically manifests itself in brown (like the soil) and black colors (like charcoal).  When making compost for example, when they say you need a balance of browns and greens, they are talking about carbon and nitrogen.

Good sources of carbon:
 (from http://www.gardenorganic.org.uk/composting/compost_1.php)
•    Cardboard eg. cereal packets and egg boxes
•    Waste paper and junk mail, including shredded confidential waste
•    Cardboard tubes
•    Glossy magazines (although it is better for the environment to pass them on to your local doctor’s or dentists' surgery or send them for recycling
•    Newspaper (although it is better for the environment to send your newspapers for recycling)
•    Bedding from vegetarian pets (eg. rabbits, guinea pigs  hay, straw, shredded paper, wood shavings)
•    Tough hedge clippings
•    Woody prunings
•    Old bedding plants
•    Bracken
•    Sawdust
•    Wood shavings
•    Fallen leaves can be composted but the best use of them is to make leaf mould
•    Wood ash, in moderation
•    Hair, nail clippings
•    Egg shells (crushed)
•    Natural fibres eg. 100% wool or cotton

Which brings us to nitrogen (N), our greens.  Nitrogen is a little harder to come by for plants and obvious sources tend to be on the greenish side eg. excrement (sorry, icky I know) which can eventually develop into ammonia which is an excellent source of nitrogen (and for cleaning ironically). 

If carbon can be considered the backbone of your plant structure, nitrogen might be considered the “protein" or muscle that helps keep things together.  Analogy-wise (because I am a big fan of analogies), a plant would not be a full plant like a human would not be a full human without its bones and muscles/organs.  Only bones and you have a skeleton (a dead dried up plant), and only muscle and you have mush (think of a cold damaged succulent?)

As it is such a major player in plant formation, let’s just be blunt and say if you have a severe nitrogen shortage, your plant is SCREWED and you need to remedy that post-haste (but not too the point that excess nitrogen is applied).  As it has such a major role, any sign of your plant looking like its having trouble could nearly always be chalked up to a nitrogen deficiency.

Sign of Nitrogen deficiency include:
-stunted growth
-yellowing of plants (ADDENDUM: from the older leaves and then upwards)

Unfortunately nitrogen does not like to stay put and fix itself to the soil (unlike in beans and peas which have beneficial bacteria) where plants can get to it, or it gets washed away by water via human or natural methods.  So unless plants are receiving a good steady source, regular applications of compost or other organic fertilizer might be needed.

Natural Sources of Nitrogen (and pretty much P/K too):
-Grass/leaves: (avoid black walnut leaves which can impede growth!) help with their breakdown by shredding/compost ahead
- Potash (n-phos): Wood ashes, so if you like a good wood fire, use them ashes later in your garden!  (REMEMBER: Never burn treated wood!) (ADDENDUM: Can be VERY alkaline, so use caution when adding as you don't want to whack your pH out of line! Thanks Jeansgarden for noting this!)
-Tea leaves w/paper bags: good NPK all around and trace minerals; can toss whole or cut up
-Urine (as I often tout, really is great!) - full of uric acid and nitrogen and phosphorus... a great compost activator, so you if you have a guy in the house, tell him that #1 is great in the garden.
-Ammonia: is alkaline (basic) and balances out acid, breaking down to nitrogen later (great for slug killing too)
-Brewing grain (if you live near breweries): the fermented items leftover from beer or alcohol brewing are a rich source of nitrogen and trace minerals (apparently farm animals like it for feed too).
-Coffee grounds: Either from your own pot/pods/filters or your local Starbucks or coffee shop is usually more than happy to let you take their bags of grounds, keeping them from making a trip to the dump behind the store. It's full of trace minerals, carbon-nitrogen of 20-1 and is slightly acidic.

From the Starbuck's website:
Primary Nutrients
Nitrogen    ________________________________________    1.45%
Phosphorus    ________________________________________    ND ug/g
Potassium    ________________________________________    1204 ug/g

Secondary Nutrients
Calcium    ________________________________________    389 ug/g
Magnesium    ________________________________________    448 ug/g
Sulfur    ________________________________________    high ug/g

My husband is awesome and even brings in his coffee grounds from his office coffee maker without me even asking!

The next macro-nutrient would be phosphorus (P) and what helps plants mature and grow and develop flowers to make what every living thing apparently wants: BABIES.  You might think of it like hormones (I’m not saying this is what it is, but to remember this helps).  Phosophorus can get “locked up” in the soil at times when the soil is too acidic and so to free it from the soil, soil pH must be increased and alkaline for the plants to be able to uptake it.  Early growth requires phosphorus and eventual “woodifying” of plants such as for trees and shrubs.  It’s best applied in its soluble form in the summer rather than the spring as soft new growth is wanted earlier in the season.

Sign of Phosphorus deficiency include:
-stunted growth
-bitterness in crop

Natural Sources of Phosphorus:
-bananas: bury them (cut them up best); some say to dry them in the oven and crumble them into the soil

Potassium (K) is highly important in plants, in the same fashion humans need it.  Both of us require proper fluid balance in our cells via potassium channels, and this is why potassium is essential for us both.  It also keeps enzymes working effectively and all things living run on enzymes and proteins!  This vital element also ensures good root formation and allows plants store their food.

Sign of Potassium deficiency include:
-stunted growth
-deformities
-yellowing leaves
-weak stems
-premature fruit drop

Natural Sources of Potassium:
-Bananas: bury them (cut them up best); some say to dry them in the oven and crumble them into the soil
-Seaweed: made yourself some homemade sushi or Asian food? Use leftover seaweed in the garden!

More up in a day or so. Prepare for: Soil Nutrition Part 2 of 3:  Calcium, Magnesium, Iron & Sulfur!