Drainage of Agricultural Lands - Practices of Irrigation and On-farm Water Management - page 330

In some sensitive plants, prolonged water logging damage the root system, and
consequently the plants die due to lack of nutrient and water uptake.
9.1.4 Benefits from Drainage
9.1.4.1 Major Benefits
(a) Makes favorable soil condition for plant roots to grow
(b) Increases the availability of plant nutrients
(c) Reduces the hazard of toxic substances in the soil
(d) Helps in the decomposition of organic matter and thereby increases the
availability of N 2 .
(e) Extends the period of cultivation
(f) Provides a better environment for crop emergence and early growth
(g) Can reduce soil compaction
9.1.4.2 Additional Benefits
Drainage helps to get ride of the following problems:
(i) Ponding of water during the summer may cause scalding (burn by hot water)
of the crops.
(ii) A health hazard is created by mosquitoes which breed in ponded field.
(iii) A high water table prevents the soil to warm up readily in spring and thus affect
seed germination.
(iv) Plant diseases are more active under water-logged conditions. Fungus growth
is particularly prevalent (most common).
(v) Bearing capacity of water-logged soil is low. Thus, create problem with
construction and compaction of soil by animals and machines.
9.1.5 Types of Drainage
Drainage may be either natural or artificial. In case of natural drainage system, water
flows from the fields toward low-land, then to swamps or to lakes (in some places
local name is “khal” or “bill”) and then to rivers, through natural system. In some
cases/soils, the natural drainage processes are sufficient for plant growth and pro-
duction of agricultural crops, but in many other soils, artificial drainage is needed
for efficient agricultural production.
Artificial drainage is divided into two broad classes: (i) surface, and (ii)
subsurface. Some installations serve both purposes.
9.1.5.1 Surface Drainage
Surface drainage is the removal of water that collects on land surface. It is a system
of drainage measures, such as open drains and land forming, to prevent ponding by
diverting excess surface water to a collector drain.