# Thread: Story Problem NO IDEA

1. ## 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.

2. Originally Posted by Pratt86
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.

3. makes sense now