# SCIENCE/MATH

posted by
**SAMY**
.

Land growing continuous grain corn as a cash crop loses soil at a rate of

14.0 metric tonnes ha-1 yr-1. This is a fertile soil, which has an organic matter content of 3.8% and nitrogen content of 0.35% (both by mass).

a)Calculate how long it will take to erode the entire Ah horizon of this soil. Assume an initial Ah thickness of 7 inches and a bulk density of 1.25 g cm-3 prior to the onset of cultivation .

b)If the entire Ah horizon is lost, calculate how many kg of manure you would need to add per hectare in order to replace the lost organic matter if manure is assumed to be 100% organic matter.

c)If nitrogen (as ammonium nitrate) sells for $0.70 kg-1, calculate the dollar value of nitrogen that would have to be added per hectare in order to replace the lost nitrogen.