CCA Irrigation Management and Water Use 2

Question 1

Irrigation water with an Electrical Conductivity (ECw) greater than 3.0 dS/m is classified as:

Accepted Answer

High salinity — requires good drainage and salt-tolerant crops

Answer

Water with ECw of 3.0–6.0 dS/m is classified as high salinity and can be used only with good drainage management and salt-tolerant crops, as it poses significant osmotic stress risk.

Question 2

The leaching fraction in saline soil management is defined as the:

Accepted Answer

Fraction of applied irrigation water that drains below the root zone

Answer

The leaching fraction is the portion of applied water that percolates below the root zone, carrying accumulated salts out of the crop root zone to prevent toxic buildup.

Question 3

Sodium Adsorption Ratio (SAR) of irrigation water is used to assess the risk of:

Accepted Answer

Soil structure degradation due to sodium-induced clay dispersion

Answer

High SAR causes sodium to displace calcium and magnesium on cation exchange sites, leading to clay dispersion, reduced infiltration, surface crusting, and loss of soil structure.

Question 4

Subsurface tile drainage is primarily installed to:

Accepted Answer

Remove excess water from saturated soils to improve aeration and trafficability

Answer

Tile drainage removes gravitational water from saturated soils, improving soil aeration for root development, trafficability for field operations, and reducing waterlogging stress on crops.

Question 5

A center-pivot irrigation system with a flow rate of 800 gpm covering 125 acres has an application rate calculated to be 0.5 in/hr. The primary concern at this application rate is:

Accepted Answer

Application rate exceeding soil infiltration rate causing runoff

Answer

When application rate exceeds the soil's infiltration rate, water ponds on the surface and runs off, reducing irrigation efficiency, causing erosion, and potentially carrying nutrients off-field.

(CCA) Certified Crop Advisor Practice Test

(CCA) Certified Crop Advisor Practice Test

CCA Irrigation Management and Water Use 2