Agronomy Irrigation and Water Management 2

Question 1

What is the most critical growth period for corn when water stress causes the greatest yield loss?

Accepted Answer

Silking through early grain fill (R1-R3)

Answer

Water stress at silking and early grain fill (R1-R3) can cause poor pollination, kernel abortion, and the greatest proportional yield loss in corn.

Question 2

What is the primary cause of soil salinity buildup in irrigated fields in arid regions?

Accepted Answer

Salt accumulation from irrigation water combined with inadequate leaching

Answer

Irrigation water carries dissolved salts that accumulate in the root zone as water evaporates or is transpired, especially in arid climates with insufficient rainfall to leach salts.

Question 3

What is leaching requirement in irrigated agriculture?

Accepted Answer

Additional irrigation water needed to flush excess salts below the root zone

Answer

Leaching requirement is the fraction of applied irrigation water that must pass through and below the root zone to prevent salt accumulation to damaging levels.

Question 4

Which irrigation scheduling method uses crop canopy temperature to detect plant water stress?

Accepted Answer

Infrared thermometry (crop water stress index)

Answer

The crop water stress index (CWSI) uses infrared thermometers to measure canopy temperature, since stressed plants close stomata and become warmer than well-watered plants.

Question 5

What is the primary benefit of subsurface tile drainage in humid regions?

Accepted Answer

Removes excess water from root zone, allowing earlier field operations and better aeration

Answer

Tile drainage removes excess soil water, improving soil aeration for root growth, allowing earlier spring field access, and reducing denitrification losses.

Agronomy Practice Test

Agronomy Practice Test

Agronomy Irrigation and Water Management 2