9.25 In the garden. Organic Gardening magazine, describing how to improve your garden’s soil, said, “Since a 6-inch layer of soil in a 100-square-foot plot weighs about 45,000 pounds, adding 230 pounds of compost will give you an instant 5% organic matter.”
(a) What percent of 45,000 is 230?
(b) Water weighs about 62 pounds per cubic foot. There are 50 cubic feet in a garden layer 100 square feet in area and 6 inches deep. What would 50 cubic feet of water weigh? Is it plausible that 50 cubic feet of soil weighs 45,000 pounds?
(c) It appears from part (b) that the 45,000 pounds isn’t right. In fact, soil weighs about 75 pounds per cubic foot. If we use the correct weight, is the “5% organic matter” conclusion roughly correct?