losing humus in warm climates

Discussion in 'Homesteading Questions' started by Paul Wheaton, Aug 24, 2005.

  1. Paul Wheaton

    Paul Wheaton Well-Known Member

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    I had a discussion recently about the advantages and disadvantages of warmer climates vs. cooler climates.

    One issue that seemed important to me was related to horticulture: it has been my understanding that it is easier to build soil in cooler climates. In warmer climates, soil microbes work all year at breaking down humus. So if you add compost to your soil, it may last a few years where there is a short growing season, but last only a year where it doesn't freeze.

    Others were skeptical. And I have to admit that I don't have any hard data to back me up on this. And now I'm starting to doubt myself.

    Anybody know about this and can chip in a bit? Anybody had a garden where it's warm and a garden where it's cool?
     
  2. YuccaFlatsRanch

    YuccaFlatsRanch Well-Known Member Supporter

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    The Texas A&M soil scientists agree with your statements.
     

  3. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    First of all, let’s get our terms straight. Humus is not the same as organic matter. “Humus” is the end product of “organic matter” decomposition. Some scientists use the term “stabilized organic matter” instead of “humus.” Technically, humus cannot be decomposed any further (it may decompose at a very, very slow rate). For any given climatic region, the humus content of a mineral soil is primarily determined by its clay content. The higher the soil’s clay content, the higher its humus content.

    Organic matter can be anything from chopped cornstalks, to plowed-down grasses and legumes, manure or compost. Some scientists call this material “active organic matter.” In other words, this matter is actively breaking down in the soil. Now any environmental condition that favors bacterial action, is going stimulate the decomposition of active organic matter, thereby reducing its amount in the soil. Moisture, warm temperature, good aeration, and available nitrogen will all quicken decomposition and the loss of active organic matter.

    So, to answer your question, if two soils, one in Minnesota in one in Texas, had the identical moisture, nitrogen and aeration status and clay content, the cooler soil would lose it’s actively organic matter more slowly (have a higher organic matter content for a longer period).
     
  4. sylvar

    sylvar Well-Known Member

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    Well said CabinFever.

    Shane
     
  5. Grandmotherbear

    Grandmotherbear Well-Known Member Supporter

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    Speaking from experience, amending my heavy clay Virginia soil lasted longer than amending my south Florida sand, which turns back into Florida sand inside of 3 months - unless extremely heavily mulched, which will then last 6 months.
     
  6. Jenn

    Jenn Well-Known Member Supporter

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    But GMB is comparing clay to sand, with not much difference in temps. Anyone with hotter clay? Or cooler sand?

    I gardened in USDA zone 8 (heat sone 9) central TX which has caliche and lowish rainfall, and zone 8 southern England (heat zone 3) with lots more rain. Have to say the soil- chalk clay- is same as caliche just it's wet not baked solid. Here the organic material lasts longer, and there's automatically more of it because of the rain and/or the temp not sure which. Guess it's the temp- when it's cool enough everything slows down and the only rotting is slugs and mold consuming everything mostly the live plants! Maybe with less, slower plant growth there's less consumption of humus to grow the plants?!?

    What's amazing to me is both Centr TX and Southern Eng (or at least here on the chalk) started as the bottom of an old ocean but one, with aeons or whatever of rain has grown enough trees (and fallen leaves) to build up a good level of soil on top of the chalk. Texas- well- too dry to build up any natural humus. Also in comparing TX rainfall- identical to that in SD where my grans farmed- the rain goes further where it doesn't evaporate so quickly so the soil is much deeper, they can grow a lot mroe grains etc, in SD. (But I don't think it started as chalk seabottom there)
     
  7. plowhand

    plowhand Well-Known Member

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    I have raised large gardens in the coastal plains of both North and South Carolina. Living on a farm there were always good amounts of stable manure available for the garden. It was not uncommon to spread some in the fields. However there never has been enough to broadcast 2" deep across whole fields. We nearly always furrowed out the rows and placed our compost in the bottom of the furrow, and then made a planting ridge over the compost. I can say from experience that by fall you turned up very little compost when you disced up the garden for winter. Litter such as cornstalks or oat straw disappears easily in six months. It seems to rot faster the more rain we have. It really does not seem to matter to much if it's clay land or sand. Loam seems to benefit the longest from any sort of organic matter . The best way I have found so far is to add a fair amount of organic material any time I get the chance. I never burn off any crop field unless I need to get rid of noxious weeds. Too many idiots around here burn off the fields after they make a crop. Well, they did berfore the recent acceptence of no-till crops. It made it easier to clean up the land for the next crop, or so they thought
     
  8. Ramblin Wreck

    Ramblin Wreck Well-Known Member Supporter

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    My Dad always rotated crops and used "green manure" effectively (rotated rye grass, cow peas, and sometimes buckwheat, plowed one in and planted the other). I'm doing the same on some sandy soil that I'm prepping for a garden spot now. You can actually see the soil getting darker with each planting. It's hard to make southern soil as rich as you'll find in the mid west, but with plant rotation and a longer growing season, you can grow more than you want to pick!
     
  9. Paul Wheaton

    Paul Wheaton Well-Known Member

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    Excellent info! Thanks everybody!