The difference between irrgation and drainage is that (a) irrigation is the artificial application of water to soil or land in order to supplement insufficient rainfall, while drainage is the process whereby excess water is removed from the soil or farmlands
(b) Four systems of irrigation are: (i) Surface irrigation (ii) Sub-surface irrigation (iii) Sprinkler irrigation (iv) Drip irrigation.
Two systems of drainage are: (i) Surface drainage (ii) Sub-surface or underground drainage.
(i) Surface irrigation: (i This could be in form of flooding, furrow, contour ditch. (ii) Water flows along the surface of land to farms. (iii) Wate overflows its banks and water the surrounding areas. (iv) It is very cheap and water is distributed evenly on the so: surface. (v) Volume of water may be difficult to control especially in flooding.
(ii) Sub-surface irrigation: (i) Water applied below the ground surface. (ii) It involves the use of tiles or perforated pipes. (iii) Evaporation losses from soil is minimal. (iv) Used in soils having a low water holding capacity. (v) It does not disturb the movement of machines.
(iii) Sprinkler irrigation: (i) Water is sprayed into the air and allowed to fall on the ground in form of rain (ii) Water is pumped out through the nozzles. (iii) It requires high water pressure to operate. (iv) It is convenient in areas of wate scarcity. (v) It is very expensive to purchase and maintain.
(iv) Drip irrigation: (i) Water is discharged through nozzles called emitters. (ii) The emitters deliver water to the soil surface near the base of the plant. (iii) It economises the use of water. (iv) It operates with slower line pressure. (v) It is also expensive to set up and maintain.
(i) Surface drainage (i) It is the orderly removal of excess water from the land surface. (ii) It involves the use of open ditches, field drain and land grading. (iii) It is very cheap to construct. (iv) It occupies good land space that can be used for planting. (v) ii hinders the passage of machine like tractors.
(ii) Subsurface or underground drainage: (i) It is the orderly remove of excess water from the soil. (ii) It involves the use of tiles or moles which are buried below the ground. (iii) It does not pose any threat to machines. (iv) It leaves the field free from surface obstruction.