Pollution of Water Resources from Agricultural Fields and Its Control - Practices of Irrigation and On-farm Water Management - page 262

Vacuum
Hand Pump

Neoprene
Tubing

Stopper
Assembly

(a) (b) (c)

Fig. 7.4 Water sampling equipments ( a ) ceramic cup, ( b ) vacuum suction pump, and ( c ) water
sampling arrangement (Courtesy: Soil Moisture Equipment Co.)

Collection of water sample following the crop period is also necessary to monitor
the residual nutrients, specially during rainy/wet periods.
To determine the total solute leaching during a particular period, determination of
solute concentration and correct estimation of leaching amount or deep percolation
is a prerequisite. Duration of a particular leaching event may be fixed depending on
the date of sample collection such as 5 days prior to 5 days post-sampling date.
Leaching amount may be estimated using field water balance equation or other
reliable techniques (e.g., tensiometer readings, TDR, or Neutron moisture meter
data).
Determination of basic infiltration rate and hydraulic conductivity particularly in
situ condition, and determination of soil organic matter is needed to interpret the
solute transport data.

7.6.3 Determination of Solute Concentration

It is beyond the scope of this topic to discuss various methods for determining differ-
ent solutes/pollutants in the water and/or soil sample. The readers are referred to the
relevant analytical topics/handbooks, such as Standard Methods for Examination