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

Low salinity — suitable for most crops

Answer

Medium salinity — requires moderate leaching

Answer

Very high salinity — generally unsuitable for irrigation

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

Ratio of soil EC to irrigation water EC

Answer

Percentage of irrigation water lost to evaporation

Answer

Proportion of rainfall that recharges the water table

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

Heavy metal toxicity to crops

Answer

Boron toxicity in sensitive crops

Answer

Increased weed pressure from waterlogged soils

Question 4

Subsurface tile drainage is primarily installed to:

Accepted Answer

Remove excess water from saturated soils to improve aeration and trafficability

Answer

Increase irrigation water storage in the root zone

Answer

Prevent lateral movement of nutrients to field edges

Answer

Reduce evapotranspiration demand on irrigated 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

Underapplication causing crop water stress

Answer

Excessive deep percolation and nutrient leaching

Answer

Freezing of water in the lateral pipes during night operation

Question 6

Regulated deficit irrigation (RDI) is a strategy where:

Accepted Answer

Irrigation is intentionally withheld during drought-tolerant growth stages to save water without significant yield loss

Answer

Crops are irrigated to 100% ET replacement throughout the season

Answer

Water is applied only through subsurface drip systems

Answer

Fields are irrigated based solely on calendar date rather than crop need

Question 7

The primary advantage of using NDVI-based remote sensing imagery for irrigation management is:

Accepted Answer

It identifies spatial variability in crop water stress and canopy health to guide variable-rate irrigation

Answer

It directly measures soil water matric potential across a field

Answer

It replaces the need for weather station ET data entirely

Answer

It measures the quantity of water applied by sprinkler systems