Agriculture Reference
In-Depth Information
3.2.3 Factors Affecting Border Performance and Design
3.2.3.1 Soil Type and Infiltration Characteristics
Soil infiltration characteristics have the biggest influence on design border inflow,
time of inflow for specific field and crop condition, length of border, and application
uniformity. Infiltration rate for a soil type and surface texture varies from farm to
farm, field to field, and throughout the growing season; typically because of the
field preparation, cultural practice (such as weeding, irrigation), and field traffic. To
approximate the infiltration amount based upon advance and opportunity time for a
border, a correlation is made using cylinder infiltration test data.
3.2.3.2 Border Inflows
For a particular soil and crop condition, the length of border run and width varies
with the available flow rate. Insufficient water supply can cause the water advance
to prolong, resulting in a reduction of efficiency. On the other hand, time of advance
decreases with the increase in flow rate. Thus, an increase in unit inflow rate can
reduce deep percolation losses and improve application efficiency.
3.2.3.3 Longitudinal Slope
Optimum longitudinal slope may aid in achieving better uniformity and efficiency.
3.2.3.4 Irrigation Depth
The duration of irrigation is dependent on the depth to be applied.
3.2.4 Design Parameters
The main design parameters for border irrigation system include the following:
•
unit flow rate,
Q
•
length of border,
L
•
width of border,
W
•
slope,
S
•
cutoff time,
t
co
The slope of a border is controlled by the natural slope of the field and can be
modified only if the orientation of the field with respect to the main slope of the land
is changed or when land grading is applied. Appropriate slope for border depends
on soil (type, profile depth) and crop combination.
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