Farms.com Home   News

Soil Based Irrigation Scheduling

By Ben Faber
 
A rule of thumb is that irrigation should be done when about 50% of the water has been depleted from the soil in the plant's root zone. This 50% value, however, allows a buffer of water in the soil in case the weather suddenly turns hot and windy. Sandy soils hold less water than clay soils and must be irrigated more frequently. A common misperception is that it takes more water to grow plants in sandy soil than in clay soil; however, the total amount required for the whole year is the same for both soil types. The amount of sunlight, wind, temperature, and humidity control how much water a plant needs, and the soil is only the reservoir.
 
Determining water content by soil texture
 
To check the water content in the soil based on the soil texture, dig 8 to 16 inches down into the soil with a trowel, shovel, or soil tube and feel the soil. At about 50% available water:
 
  • coarse soil appears almost dry and form a ball that does not hold shape
  • loamy soil forms a dark ball that is somewhat moldable and can form a weak ribbon when squeezed between the fingers
  • clayey soil forms a good, dark ball, makes a ribbon an inch or so long, and slightly sticky
 
This method, however, gives only an approximate water content; instruments can give more precise readings.
 
 
feel method
 

Trending Video

Grain Markets - Luke Beckman

Video: Grain Markets - Luke Beckman

Earlier this week, Bryce Doeschot caught up with Central Valley Ag's Luke Beckman to see what is catching his attention in the markets as harvest kicks into full swing. Here is their conversation from Wednesday afternoon.