Tuesday, May 18, 2010

The Scoop on Poop

As you may have read, between snow storms I have managed to find some time to work in my yard and in my garden. I am so excited to have composted manure from my own horses to amend my lousy soil. I guess you'd have to say that either I'm very weird or I am a true gardener if I get excited about playing with horse sh*t! I got to thinking that others may not know the scoop on poop....so here's what I have learned:

  • Etiology of the word, sh*t: Before the advent of commercial fertilizer manure was transported by ship to help farmers enrich soil and produce better crops. It was shipped in dry bales to limit the weight the ship had to carry. But, if the manure became wet while at sea, it not only became heavier, but it would begin to ferment. A by-product of the fermentation of manure is methane gas. The gas would collect and if some hapless sole came below decks at night carrying a lantern....well, you can imagine the problem that would ensue. So, once it was determined why the explosions were occurring, bales of manure were marked, "Ship High in Transit" to remind sailors where to store the bails so that water would not begin the process of creating explosive methane gas. Thus the term S.H.I.T, a shortened form of the label, came to mean manure. (Source: Rocky Mountain Haflinger Association, Jan - March 2010 Newsletter, "Haffie Trails")
  •  Manure as Fertilizer: Manure can be used to add organic matter and nutrients to soil. The benefits to be derived from manure vary with the type of manure used and the way in which it is handled. The best manures for gardening come from ruminants. These are animals with several stomachs, such as cows, sheep and llamas. The food the ruminant eats is better digested and weed seeds are killed. The  digestive system of a horse does not kill as many weed seeds. Manure from chickens has a very high ammonia content so applying fresh poultry manure can burn your plants. Fertilizer has three main nutrients: Nitrogen, Phosphorus and Potassium. When you buy commercially prepared fertilizer the container will often list three numbers, such as 21-4-8. These numbers refer to the relative amount of each of the key nutrients in the order listed. Remember the words UP, DOWN and PRETTY to remember just what the nutrients do for your plants. Nitrogen helps promote healthy, green top growth. The Phosphorus supports root growth and the Potassium helps make large, beautiful blooms. That being said, it's interesting to know that horse manure has a rating of .7-.2-.7, cow manure is 1-.7-1 and chicken manure is 1.7-2.4-1.7*. The nutrient value of fresh horse manure is pretty darn low and to get close to the nutritional rates of commercial fertilizer, you'd need to heap a ton of manure onto your lawn and garden. Not very practical and not at all pretty! In addition, I have read that using manure as fertilizer may actually deplete nitrogen in your soil, especially if you have wood shavings or sawdust mixed in with the manure. The organisms from the soil that break down the manure require extra nitrogen to break down the carbon found in the wood products. Thus, your soil may have less nitrogen than if you had not applied the manure at all. And, as mentioned above, it is the nitrogen that promotes nice, green growth, so your grass may suffer. Confusing, huh? In my opinion, the long term benefits to be gained from spreading manure outweigh the possible negative effects, if it is done correctly. The negative effects can be ameliorated by minimizing the amount of bedding that winds up in your manure, spreading no more than the recommended amount of manure and by adding additional nutrients. So, are you totally baffled yet? It gets even more complicated! Manure contains salts. Different manures contain different levels of salts. Some soils already have too much salt. Salt at certain levels is not beneficial. Therefore this may limit the amount of manure you can spread at a given time. To determine how much manure you should add to your field or garden, you need to know the current nutrient levels, including salt, of your soil.  Local extension agencies generally have a soil testing program. They also have all kinds of handy dandy charts that will explain how much manure to add, based on your test results.(* nutrient rates vary depending on whether bedding is or is not included. Source: Colorado Extension Service, "Using Manure in the Home Garden")
    • Composting Manure: If your head isn't already spinning, read on! Although composted manure loses some of its nutritional value because nutrients leach out in rain (unless compost bins are covered), it is an excellent source of organic material to add to your soil. Organic material helps hold moisture and nutrients in your soil. Ideally soil should be comprised of at least 5% organic material. I have sandy soil. The organic content is negligible so I try to add organic material when turning my garden or planting new shrubs, trees or flowers. This year some of that organic material is coming from my own compost pile. Composting manure requires that you have space where a fairly large mass of manure can sit over a period of time. Ideally it helps to have at least three manure bins or piles. One that you are currently using for your fresh manure and two others that are 'cooking'. The size of the pile depends on the number of horses you have and how much bedding is included in the manure, but anything less than 3'X3'X3' will not have enough mass to compost. Each pile should be able to hold 2-4 months worth of manure. That can be a lot of sh*t stuff! If conditions are right, organisms begin to break down the manure almost immediately. Organisms are at work in your pile if it begins to heat up. I purchased an inexpensive 'instant read' thermometer that I taped to the end of a painting pole. I can poke the thermometer into the pile and read the temperature. Within a day you should find that the inside temperatures rise and begin to approach 140 degrees. If the pile does not heat up it could mean that the manure is either too wet or too dry, or that it doesn't have enough air. The pile needs to be 'turned'. The contents need to be mixed up. The contents are too dry if when you form a ball and squeeze it together it falls apart. Add a little water. If the contents are too wet, allow the pile to dry out by turning it more frequently and/or by adding dryer material. If you live in a very wet or very dry climate you may find that you need to cover your compost pile with a tarp to maintain the optimum moisture level. If the pile begins to cool it is time to turn the manure again to expose all material to oxygen which allows the microorganisms to work. Some folks layer PVC pipe with small holes in their manure piles to introduce air without the need for turning. After several months the manure will have been  transformed into lovely organic matter and will stop 'cooking'. If temperatures surpassed 140 for a period of days in two different heat up cycles, weed seeds, parasites and insect eggs or larvae will have been killed and your composted manure will make an excellent soil amendment. 
    Our compost piles are dug into a small hillside, so they are protected from the drying wind to some degree. If you look closely at the pile just under the bucket, you can see steam coming from the compost as it is being turned.

    This is my thermometer....a slightly bent model...that I use to measure the temperature of the composting manure. 

          1 comment:

          1. Very informative blog post. I am featuring it today on our blog site, http://blogmidwestlabs.com

            This information should be in a guide for growers to help educate them on the benefits of horse manure.

            Thanks Again!

            Brent Pohlman
            Midwest Laboratories
            Omaha, NE


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