Fact 1: Soil can be depleted of nutrients.

Fact 2: An important nutrient commonly added to soil is nitrogen.

Given the two facts above, answer the question "Nitrogen depletion is a condition of some:" with the following options: 
- bushes
 - humans
 - animals
 - soils
 - disease
 - legumes
 - mammals
 - Birds


 

    soils     