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Math Help - Story Problem NO IDEA

  1. #1
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    Story Problem NO IDEA

    Story problem my teacher gave me and I have no idea where to start. If someone can get me started I would greatly appreciate it. Thanks

    If a prairie soil that had 6% organic matter under natural prairie vegetation in 1860 now only has 3% organic matter in the top foot, how many lbs of N have been lost per acre ?

    Assume that soil organic matter was only depleted in the top foot. Assume
    that nitrogen makes up 5% of the mass of soil organic matter. Assume that 1
    cubic foot of soil weighs 80 lbs. Remember that 1 acre = 43,560 square
    feet.
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  2. #2
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    Quote Originally Posted by Pratt86 View Post
    Story problem my teacher gave me and I have no idea where to start. If someone can get me started I would greatly appreciate it. Thanks

    If a prairie soil that had 6% organic matter under natural prairie vegetation in 1860 now only has 3% organic matter in the top foot, how many lbs of N have been lost per acre ?

    Assume that soil organic matter was only depleted in the top foot. Assume
    that nitrogen makes up 5% of the mass of soil organic matter. Assume that 1
    cubic foot of soil weighs 80 lbs. Remember that 1 acre = 43,560 square
    feet.
    Work logically and step by step. One acre is 43560 square feet and you are going 1 foot deep so you are looking at 43560*1= 43560 cubic feet of earth. 1 cubic foot of soil weighs 80 lbs so 43560 cubic feet weighs (80)(43560) pounds. Now find 3% and 6% of that to determine what weight of organic matter each of those years. Finally, use the fact that 5% of that weight is Nitrogen.
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  3. #3
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    makes sense now
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