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) we did this question before,
lost soil=soil mass
14000kg/10000m^2 yr * time=7in*1m/39.37in*1.25E3kg/m^3
time=7/39.37 * 1.25E3 /(1.4) years
and the answer was: 158.7 years..
I don't understand part b!
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 .