MODULE 7

Question 1

Lack of water causes

Answer 1

• poor crop stand
• reduction in yield
• predisposes the plants to pests and diseases

Question 1

Water management

Answer 1

An integrated process of timely application of the needed amount of water and the removal of excess water from the field to ensure optimum growth and crop productivity

Question 2

Blossom end rot of tomato

Answer 2

caused by a Ca deficiency aggravated by lack of water

Question 3

Excess water causes:

Answer 3

• too much leaching of nutrients from the soil and leads to high acidity
• water-logged condition which leads to reduced root development and death of roots
• predisposes the plant to root-rotting pathogens

Question 4

Soil factors

Answer 4

affects water holding capacity, water percolation and includes soil structure, texture and depth

Question 5

Climatic factors

Answer 5

affects the rate of water losses through evaporation & transpiration and includes temperature, length and intensity of sunshine, relative humidity, wind movement and rainfall increases level of soil moisture

Question 6

Plant factors

Answer 6

includes rooting characteristics, drought tolerance and growth stages

Question 7

Gravimetry

Answer 7

involves oven drying a sample of soil and compute soil moisture content

Question 8

Tensiometer

Answer 8

to measure the water potential
which is inversely related to amount of available
water

Question 9

Threshold level at which water can be depleted

Answer 9

Usually, the threshold level is 50 % of the available water

Question 10

Measurement of evapotranspiration rates

Answer 10

to determine values of evapo- transpiration rates of the crops over a short time intervals

Question 11

Observing visual symptoms of plants

Answer 11

• Temporary wilting/leaf rolling
• Color of the foliage (beans turns yellow, eggplant turns bluish green leaves)

Question 12

Irrigation in sandy soil is needed when

Answer 12

Appears dry but doesn’t form a ball

Question 13

Irrigation in loam soil is needed when

Answer 13

Somewhat crumbly but particles hold together

Question 14

Clay

Answer 14

somewhat pliable, forms a ball but does not readily form a ribbon

Question 15

Sand-cum-mini plot technique

Answer 15

reduce artificially, the available water holding capacity of soil in root zone depth in the mini plot by mixing sand with it.

Question 16

Furrow method

Answer 16

Applied water seeps into side and bottom of furrows to attain desired wetting

Question 17

Basin method

Answer 17

Trees are irrigated individually, solves most of the limitation of the flooding method

Question 18

Flooding method

Answer 18

water is applied by flooding the entire field

Question 19

Sprinkler irrigation

Answer 19

Highly-pressurized water is delivered through network of pipes and comes out as fine droplets

Question 20

Drip system

Answer 20

Water is applied directly to the root zone in small amount and continuously until desired wetting of soil is attained

Question 21

Sub-surface irrigation system

Answer 21

Water is applied below the soil surface (through the underground system) and reaches plant root zone by capillary movement

Question 22

Water impounding system

Answer 22

structure to collect rain water and run-off water