GAP Soil Science & Analysis 3

Question 1

Which soil amendment is most appropriate to raise the pH of an overly acidic field soil?

Accepted Answer

Agricultural lime (calcium carbonate)

Answer

Agricultural lime (calcium carbonate) neutralizes soil acidity and raises pH by releasing calcium ions that displace hydrogen ions from exchange sites.

Question 2

What is the primary purpose of a soil percolation test in a GAP context?

Accepted Answer

Assessing how quickly water drains through the soil profile

Answer

A percolation test measures water drainage rate, which is critical for assessing flood risk, irrigation scheduling, and pathogen runoff potential on produce farms.

Question 3

Soil organic matter content directly improves all of the following EXCEPT:

Accepted Answer

Soil particle size (texture)

Answer

Soil texture (the proportion of sand, silt, and clay particles) is determined by geology and cannot be changed by adding organic matter.

Question 4

A soil bulk density reading of 1.7 g/cm³ in a crop field most likely indicates:

Accepted Answer

Significant compaction limiting root growth and water infiltration

Answer

Bulk density above 1.6 g/cm³ in most agricultural soils signals compaction that restricts root penetration, reduces pore space, and limits water infiltration.

Question 5

When should a GAP producer collect soil samples for the most accurate fertility recommendations?

Accepted Answer

At least 2–4 weeks after fertilizer or lime application

Answer

Sampling too soon after fertilizer or lime application gives skewed results; waiting 2–4 weeks allows amendments to equilibrate with the soil.

(GAP) Good Agricultural Practices Certified Practice Test

(GAP) Good Agricultural Practices Certified Practice Test

GAP Soil Science & Analysis 3