Agronomy Soil Science and Fertility 3

Question 1

Which type of soil horizon is most important for plant root development and nutrient uptake?

Accepted Answer

A horizon

Answer

The A horizon (topsoil) contains the most organic matter and nutrients and supports the most root activity.

Question 2

Potassium deficiency in crops typically first appears as what symptom?

Accepted Answer

Marginal leaf scorch on older leaves

Answer

Potassium is mobile in plants, so deficiency symptoms—scorched leaf margins—appear first on older, lower leaves.

Question 3

Which practice is most effective at reducing soil erosion on sloped farmland?

Accepted Answer

Contour farming

Answer

Contour farming involves planting across slopes to slow water runoff and reduce soil erosion on hillsides.

Question 4

Soil salinity is measured using which instrument or method?

Accepted Answer

Electrical conductivity meter

Answer

Electrical conductivity (EC) meters measure the concentration of dissolved salts in a soil-water solution.

Question 5

What role do mycorrhizal fungi play in plant nutrition?

Accepted Answer

Extend root surface area for nutrient uptake

Answer

Mycorrhizal fungi colonize plant roots and extend hyphae into the soil, greatly increasing the root's effective absorptive surface area.

Agronomy Practice Test