Thursday, February 23, 2012


I'm not exactly sure why but it seems to surprise most people to learn that we don't buy as much commercial fertilizer for our horse pastures as some seem to think we should. Horses are prodigious fertilizer producers. My job as a good farmer is to figure out how to make effective use of all they produce. An average sized horse eating an average diet produces roughly 50 pounds of manure per day. Horse manure is roughly 80 % water and in addition to water it also contains 0.3 pounds of nitrogen, 0.15 pounds of phosphorus and 0.3 pounds of potassium as well as a myriad of biologically available trace minerals and a bunch of organic matter.

This may not sound like much but over the course of a year it adds up to 18,250 lb of manure per horse. In aggregate this manure contains 110 pounds of nitrogen, 55 pounds of phosphorus and 110 pounds of potassium. We stock at roughly one horse per two acres of pasture. Interestingly but perhaps not surprisingly this is about how much NPK (nitrogen, phosphorus, potassium) our soil test suggests we add to every two acres of pasture in this part of the world. And we haven't even touched on the nutrients that are present in horse urine yet !

There are lots of folks in the commercial fertilizer business who will wince when they hear this but in my opinion there is no real way to sustainably build soil without the aid of copious quantities of manure. When it's used effectively it adds organic matter in addition to nutrients, and the list of benefits that organic matter brings to the table is far too long to list here. For a quick visual, imagine the difficulty of trying to grow plants in the type of sand you'd find at your nearest ocean beach. Then imagine trying to grow those same plants in a bag of potting soil from your local nursery. That's the difference organic matter makes.

There are two keys to effectively using manure as a fertilizer and soil builder. The first one is storing it in such a way that most of the nutrients it contains are captured, rather than leached out into the environment. The key here is adding lots and lots of carbon in the form of sawdust, shavings, hay and straw because carbon binds nutrients, particularly N,P and K. The second key is applying the surplus at a time when plants can actively use the nutrients it provides. In most of the temperate world the best time to spread manure is early to mid spring when pasture grasses are just about to hit peak growth and their demand for nutrients is similarly high.

Our cool season grasses are beginning to really come on right now. In another six weeks, our warm season grasses will begin to grow. Between now and then I'll be scraping all the excess manure and hay up from around the hay feeders, run in sheds and loafing areas. Once it's piled, I will be applying it to the pastures and then incorporating it with a chain harrow. And on that note, I hope everyone has a great weekend !


Fuzzy Punch looking very perky trotting through the field

Silky, Maisie and MyLight were having a very peaceful morning

Grand and Leo playing

Kennedy, Toledo and Rocky


B-Rad and Murphy

Fonzi and Chimano

Lighty, Alex and Darby

Tony, Homer, Apollo and Moe


EvenSong said...

Have you guys ever thought about composting the manure you gather, and waiting (usually a year, but it can be done in less time with more labor intensive methods) to spread it on your fields? This has the advantage of reducing weed seeds, parasite eggs, flies, etc. And the compost I produce from only 4-6 horses and weekly-to-bi-weekly incorporating/turning of my pile is beautiful deep rich "soil" which I use for planting beds and spreading. Just wondering if you've ever looked into it as an option.

Melissa-ParadigmFarms said...

We have compost piles from every pasture right now, we do a LOT of composting.

Bif said...

Cool and informative post. Never knew the actual quantities of the nutrient components of horse manure,,, live and learn =)

Calm, Forward, Straight said...

Thanks for the informative post!

I live on a island whose soil is primarily sand - excellent when you must dig holes, but nutritionally bankrupt. Amendment required.

My composted manure (I cold compost at the moment - takes about one year) becomes the most beautiful, rich, and most importantly moisture retaining soil you could ever want.

I'm happy to read that carbon rich matter helps bind the nutrients as I mix the hay leftovers into my pile.

I had wondered about seed sprouting verses carbon - and decided pulling a few weeds was worth it. :)

EvenSong said...

Okay, Melissa, I wasn't sure from the post. Thanks for the clarification.