soil plant water relationship

1. SOIL-WATER-PLANT
RELATIONSHIPS
SUBMITTED TO
Dr. A. K. VERMA
SUBMITTED BY
NIKHIL TIWARI

2. SOIL-WATER – PLANT
RELATIONSHIP
 Water is the basic input influencing crop production
 The amount of water required for a given crop depends
on:
 State of development of soil
 Quantity and type of fertilizer given
 Quality of water used
 Climatic conditions
Soil- water- plant relationship - Process that requires to be
regulated for maximization of yields with a given unit of water
Understanding of Soil- Water- Plant relationship is essential in
order that water management principles are applied to various
climatic, soil and cropping regions of both rain fed and irrigated
lands

3. Contd…
A. Soil factors
a) Infiltration:-
• Influences selection of irrigation methods, slope needed for the
land, length of run, irrigation application time etc.
• Soil water parameters affecting infiltration rates:-
Texture, Structure, Bulk Density, Sodium salts, Crop grown,
Irrigation water, Temperature, Tillage and Water in soil
b) Permeability:-
• Depends on soil texture and structure, presence of plant roots
and changes in temperature of water
• K= QL/A(H1-H2)
where, Q= Discharge/ unit time
A= Cross sectional area through which water
flows
H1-H2 = Hydraulic head
L = Percolation path length

4. Contd…
Soil Gravel
(clean
)
Coarse
sand
(clean)
Sand
(mixture
)
Fine
sand
Silty
sand
Silt Clay
K 1.0 or
more
1.0-0.01 .01-.005 .05-
.001
0.002-
0.0001
0.0005-
0.00001
0.0000
1 or
lesser
Measured using Constant head permeameter and Variable head
permeameter
c) Drainability and Leachability:-
• Principal factors in predicting the drainability of a soil is its
permeability and hydraulic gradient
• Leachability is directly related to drainability
d) Erodibility

5. Contd…
B. Plant factors
a) Rooting characteristics:-
• High water table limits the root growth due to lack of sufficient
aeration
b) Evapo-transpiration:-
• General rule is that 40,30,20 and 10 percent of the total ET is
removed respectively from each successively deeper one-quarter
of the rooting depth
c) Effect of soil water level on crop growth and yield:-
• Crop growth and transpiration generally decreases as the wilting
point approaches
• The point at which growth or transpiration of a plant is retarded for
want of soil water, crop characteristics, low or high evaporative
demand etc.

6. Contd…
C. Water factors
a) When to irrigate:-
• Generally irrigation shall start when 50%, but not over 60% of the
available moisture is used from the root zone
• Design frequency = (Field capacity of soil in effective crop root zone-
moisture content of the same zone at the starting of irrigation) /
Moisture use of root of crop in peak period
b) How much water to apply:-
• The amount of water to be replaced is usually 40-50% of the available
water in the root zone of the soils having a uniform available water
capacity with depth
c) Water application method:-
• Influenced by quantity of available water supply, type of soil, topography
and crops to be grown
• Methods include controlled surface flooding method, sprinkler method
and drip method