8 essential questions to ask before installing an irrigation system

Photo credit: nrcs.usda.gov

Irrigation systems offer a variety of benefits.  They allow for the growth of a wider variety of crops.  They can be timed so that the hands-on portion of crop production is a little less cumbersome.  They protect crops from irregular and dry weather conditions.  They support leaching, which can remove harmful, crop-damaging salts within in the soil.  Crops that are supported by irrigation tend to be much more productive.

To reap said various benefits, several considerations must be made and an assortment of essential questions must be answere

1. Why do you want an irrigation system?

2. What type of soil do you have?

      Do you have sandy, loamy or clay?  It could also be (and often is) a combination of the           three.

Photo credit: salinitymanagement.org

3.  What is the amount and distribution of the precipitation?

  • When does the growing area receive the most rain?   
  • Is the rain equally distributed throughout the year?
  • Are there rainy and dry seasons?
  • How much precipitation does the area receive annually?
    • Arid: less than 200mm/year
    • Semi-Arid: less than 400mm/year
    • Humid: more than 1000mm/year
    • Semi-humid: more than 800mm/year

4.  What are the temperature ranges and averages?

Are there hot and cold seasons?
Are there temperature extremes?

5.  What is the climatic water balance?

How does water flow in and out of your environmental system?
Is there a renewable source of water that can support the irrigation system?  


6.  What are the soil conditions?

  • Water storage capacity/Available water capacity (AWC)
    • This is the range of available water that can be stored in soil and be available for
      growing crops

      • formula: (water content at field capacity) – (permanent wilting point)
  • Field capacity (FC)  
    • This is how much soil moisture or water content is retained in the water after the excess water has drained and the rate of downward movement (free drainage) has decreased.  This typically takes place 2 – 3 days following rain or irrigation (assuming the soil is pervious and uniform in structure and texture).
  • Soil depth
  • Humus content
    • Humus is composed of decayed organic matter (plant and animal).  As it decomposes, it provides plants with many nutrients required for their growth.
  • The slope of the growing area
Photo credit: agry.purdue.edu

7. What crops do you want to grow?

  • What are the water demands of the desired crops?
    • Are the crops perennial (trees, vineyards) or annual (tomatoes, beans)?
    • How do the chosen crops react to water stress and irrigation?
    • Will cover crops be used?
    • How and when will crops be rotated?

8. What water will be used for the irrigation system?

  • Is there renewable water (not old water)?
  • What type of water will be used?
    • Recycled, waste or fresh
  • In what condition is the water?
    • Salt levels
    • PH levels
    • Presence of heavy metals
    • Are there hygiene issues (disease, effluence)

Once these questions have been answered, the next step is deciding the type of irrigation system that will be used.  

See also:

agricultural irrigation