Agricultural Drainage Lecture 1

Agricultural drainage is only concerned with ridding roads, sidewalks, and squares in residential neighborhoods and cities from surplus water.

The term 'drainage' is never used as a synonym for 'agricultural drainage'.

Natural drainage is always adequate and man-made drainage is never required.

The main purpose of drainage is to reduce agricultural production per unit area of cultivated land.

Agricultural drainage is the process of artificially ridding the soil of excess water only.

Excess water is beneficial for the production of crops.

In subsurface drainage, the water table is lowered to remove excess water and dissolved salts from the root zone.

The primary purpose of leaching is to increase the salinity of the soil.

Salinity can affect plant growth by enhancing the absorption of essential nutritional ions by the plant.

Drainage can lead to increased crop damage at harvest time due to wet ground.

The bluish green leaf color is a sign of healthy plant growth in saline environments.

Drainage reduces microbial decomposition in the soil.

The primary purpose of applying extra irrigation water is to supply the crops with more water.

A plant that is tolerant of high salt levels is referred to as a halophobic plant.

All plains are made up of thick, consolidated sediments.

Drainage can improve the physical properties of the soil.

A permeable layer is one that has poor water transmitting properties.

Salt-tolerant weeds are more likely to grow in areas with low salinity.

C-values between 250 and 300 indicate layers which may have a significant drainage function and which must be considered in relation to the hydraulic properties of adjacent soil layers.

A confined aquifer is a type of aquifer where the water in wells tapping such aquifers stands below the top of the pervious layers.

The water in a semi-confined aquifer is called confined water.

Unconfined aquifers are rare in drainage problems.

The water in a confined aquifer is underlain by an impervious layer.

Semi-confined aquifers do not have a vertical flow component.

In poorly drained soils, plants may suffer from an excess of water even when the water table drops.

Surface drainage is used to remove excess water from the root zone.

Land shaping or grading is done to make it more difficult for excess water to flow towards the drains.

Pipes are never used in subsurface drainage.

Poor drainage causes a decrease in crop production due to the plant roots having too much soil to grow in.

Subsurface drainage is used to remove ponding water from the surface of the land.