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michael357

On applying manure as fertilizer

Michael
9 years ago

I' m not going to touch on every par tof this topic, just the N and P aspect.
It is well known that manures have a higher ratio of P to N. Also many crops have a higher N than P demand. Going by that imbalance between the 2 , one should never attempt to supply a crop's total N requirement through the manure application or far too much P will be applied. The goal should be to apply enough manure to meet a crop's P need and supplement the N with something like blood meal that is high in N and extremely low to noP to meet the N need. This all would be best done with a soil and manure test first as well as information on what a crop's N and P requirements are.

Not managing manure this way can easily lead to a soil that is overloaded with P making the potential for it to cause P runoff or leaching pollution greater. There are additional ways to avoid those pollution hazards.

Just a thought for tonight.

Comments (20)

  • Kimmsr
    9 years ago

    Animal manures can be part of the nutrient supply to soils but should not be the only source. Just as important is vegetative waste, and that should be added at a ratio of about 3 times the animal manures. The vegetative waste is needed to help the Soil Food Web convert the animal manures into what plants can use and help keep those nutrients in the soil.

  • maplerbirch
    9 years ago

    Again P gets into the water ways via erosion, not leaching.
    Just sayin'. :)

  • Michael
    Original Author
    9 years ago

    Yup, definitely via erosion and it can in some circumstances get into groundwater via leaching. Help protect the water by managing the P load in the soil. Take regular soil samples to monitor the effects of what you're doing with respect to P. I'm harping on P because it, like N can become a pollutant when it gets away from your soil.

    Again, there are additional methods for managing P to avoid it's becoming a water pollutant.

  • Michael
    Original Author
    9 years ago

    Kimm, why the differentiation between manure and vegetative wastes?

  • wayne_5 zone 6a Central Indiana
    9 years ago

    Here is a table from Purdue.

    Dry Total
    matter NH4+N N P205 K20
    Bedding
    Species or litter (%) -- lb./ton manure--
    ----------------------------------------------------
    Swine no 18 6 10 9 3
    yes 18 5 8 7 7
    Beef no 151 4 11 7 10
    no 522 7 21 14 23
    yes 50 8 21 18 26
    Dairy no 18 4 9 4 10
    yes 21 5 9 4 10
    Sheep no 28 5 18 11 26
    yes 28 5 14 9 25
    Poultry no 45 26 33 48 34
    yes 75 36 56 45 34
    deep pit 76 44 68 64 45
    Turkey no 22 17 27 20 17
    yes 29 13 20 16 13
    Horse yes 46 4 14 4 14

    THe table didn't transcribe in a straight row. The last 3 numbers are N, P2O5, and KO2
    Here it looks like the N is higher than the P, except for poultry. Since N is more volatile, The N could drop. P tends to bind with the soil and not leach out. I use some horse manure and it is fairly low in P.

  • Michael
    Original Author
    9 years ago

    Wayne: I'm going to guess you know that all of a soil's P binding sites can get occupied by P.
    When more P gets added before a crop gets to the P on those sites, any added P will get into the soil solution and be available for leaching. Sandy soils have to be monitored closely for this phenomenon as they have fewer binding sites and water most readily percolates through them taking the P in solution along for a ride downward into water tables.

  • Kimmsr
    9 years ago

    The nutrients in manures are much and need something that can hold them in the soil rather then leaching out. Vegetative waste will do that.
    Phosphorus can, and does, flow out of the soil and into the ground water and then into our lakes and ponds, in addition to flowing with storm water from the soils surface, erosion..

    Here is a link that might be useful: About P

  • Michael
    Original Author
    9 years ago

    Kimm: you might enjoy this info from Clemson on poultry litter nutrient content.

    Here is a link that might be useful: Poultry litter info

  • glib
    9 years ago

    The reason why manures are loaded with P is that animals eat grains. No grains no excess P. Now there is a world wide scarcity of P, I myself have a garden and orchard that were originally almost without P (7ppm), I think a reasonably organized civilization should be able to optimize and solve two problems at once. Concur with Michael that most gardens will take two manure applications, then you have to fertilize in other ways.

  • Kimmsr
    9 years ago

    Michael, I read and studied that Clemson report over 10 years ago. Like other similar studies of manures it does not address using other forms of organic matter (vegetative waste) in the soil to aid in holding nutrients in the soil.
    Adding 3 parts vegetative waste to 1 part manure will do more for soil then manure alone, if only because it gives the Soil Food Web something to chew on.

  • maplerbirch
    9 years ago

    Interesting article that kimmsr posted here.

    One thing that puzzles me is while it is understood that ag crops such as corn removes P from the soil, why wouldn't one of the management practices be to, reduce P applications until the orthophosphates once again have room to bind within the soils?

    The almond orchard in particular would certainly have roots reaching down into the confinement zone for P if needed and should be able to remove lots of it in the form of almonds.
    The buffer zone would require a way to remove the saturated binding sites somehow and it seems that harvest of something would be simplest.

    Regardless, has anyone done soil testing in their organic gardens to discover that they are adding more P than they are removing through harvest?

    One would think that soils high in clay and other Exchange Sites would be able to adsorb plenty of P during the growing season, not forcing free ions of orthophosphates and therefor transported by water into the aquifers.

  • Michael
    Original Author
    9 years ago

    Good point Mapler, growing in a sand box, the opposite, would be a very different management ballgame.

    Kimm, just posting the info, use as you will. Pretty much any plant material added in any form will add essential nutrients, just depends on the source, of course.

  • Kimmsr
    9 years ago

    A number of people have posted soil test results, over the years, showing High Optimum, and greater, levels of Phosphorus mostly from adding too much manure over too short a time span and not adding enough organic matter. But then some of us have found that we could see High Optimum levels of P just by adding vegetative waste.

  • maplerbirch
    9 years ago

    Vegetative waste such as leaves and wood plugging up rivers and shorelines of lakes contain a lot of P.
    Manure comes from vegetative waste left over from an animals digestion.
    I'm lost in this discussion as to what the point of practical application we are looking for.
    I still prefer manure and compost in my garden as we are on a clay layer,(A Horizon) and over 100 ft to water.
    Does any one see that those factors make a difference to this discussion? :)

  • wayne_5 zone 6a Central Indiana
    9 years ago

    maplebirch, Yes, I think these factors make a difference in most home gardens. In my gardens one garden can have some run off on 1/3 of it to a pasture grass lot. The other 2/3s absorbs water like a sponge. None of it is tiled away.
    On garden #2 it is HIGHLY amended and it absorbs water like a sponge. If any would run off, it mostly would go to the grass lot.
    On garden #3 it mostly absorbs like a sponge also and any run off is grass channeled and goes to an adjacent field. Only one corner is tiled away and it could even be plugged up down the line, perhaps...perhaps not.

  • glib
    9 years ago

    Yes, wood has some P, but dried leaves do not. Trees typically withdraw whatever mineral is scarce from the dying leaf, and store it elsewhere.

    Grains are a super source of P because they need all that ATP to germinate. So manure will always be richer in P than mixed yard clippings. Corn is 0.3% dry weight P, wood ash is 0.1% P, which means that wood is 0.001% P. Dried manure is about 1% P. We are talking orders of magnitude difference here.

  • Kimmsr
    9 years ago

    While the levels of Phosphorus in tree may be low, 0.02 %, there is some there. Tree leaves are a good source of many nutrients.

    Here is a link that might be useful: nutrients in leaves

  • maplerbirch
    9 years ago

    As does wayne_5, my gardens are surrounded by either grass or trees, so any erosion would have no consequence to surrounding avenues to waterways.
    Soaking up like a sponge is one thing that manure does for soils.
    Would that be more important as a positive than any kind of extreme negative as orthophosphates super saturating my garden?
    I don't believe that orthophosphates are forming and leaching into the subsoil, then ultimately into the waterways, because there is so much growth in to garden to be utilizing P and not allowing excess.
    Is that safe to say? :)

  • glib
    9 years ago

    No, leaves vary a lot depending on the locale. They will have 0.1% P only if there are good P levels in the soil. Otherwise there will be less. At any rate I note that leaves have 10 times less P than manure, and non-dried wood some 500 times less. That means I can fertilize via mulch 500 times more than with manure, without incurring in P overload (and chlorosis, and the other things that come with too much P).
    Also note that wood stimulates micorrhyzal activity, improving P absorption from the soil, while providing very little of its own.

  • Michael
    Original Author
    9 years ago

    Back to the topic, applying manure as fertilizer- best to base the amount applied on what you know to exist in the soil and what the upcoming crop will need. Adding other amendments is fine as long as the amendments all compliment one another. With manure, it is possible to overload soil with P and salts ( you know, soil electrical conductivity) so, pay attention to those possibilities and avoid them.