Em4885 irrigation management practices to protect ground water

Possible Effects on Water Diversions
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CHAPTER 4
Normally, achieving this objective should have no effect on required water diversions since it
does not address irrigation system performance. However, if infiltration rates are increased and water
applications are not controlled, overall irrigation efficiency may decrease.
It should be noted that improved infiltration rates may actually increase irrigation performance.
An example would be where improved infiltration reduced losses due to surface runoff under a
center pivot.
Possible Effects on Crop Yields
Achieving this objective should have no effect on crop yields as it does not address either
irrigation, or in-field fertilizer or pesticide management. However, if infiltration rates are increased
and deep percolation increases as a result, some fertilizer might be lost. This lost fertilizer could
impact crop yields.
Possible Effects on Ground Water Quality
Increasing infiltration rates as a way of reducing the velocity and volume of surface runoff may
result in increased deep percolation without good management of irrigations. Increased deep
percolation increases the chance of nutrients or chemicals to be leached to aquifers. Also, if
sedimentation pits are installed in highly permeable soils there could be increased leaching of
contaminated water under the pit. Thus, there is the chance that achieving this Objective could
negatively impact ground water quality.
Possible Effects on Surface Water Quality
Achieving this Objective should reduce the amount of sedimentation in any surface runoff that
reaches natural water bodies. Not only is reduced sedimentation beneficial, this would also mean that
any transportation of adsorbed chemicals is also reduced.