An agricultural student plans to estimate the average soil nitrate concentration (in mg/kg\text{mg/kg}mg/kg) across a large farm to assess its overall nutrient profile. The farm contains three distinct management zones: a heavily fertilized arable field, a sheep-grazed pasture, and a naturally low-nutrient wildflower meadow.
The student's plan is as follows:
Describe two improvements to the student's plan and explain why they would be improvements.