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Alfalfa > Year-Round IPM Program > Preplanting > Field Preparation

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Alfalfa

Laser leveling a field.Field Preparation

To establish dense, vigorous stands, alfalfa requires optimal physical and chemical soil conditions. Reclamation may take many years and can be expensive. Use the table below to compare alfalfa field requirements with the conditions of your prospective site. If there are specific site problems, you will need to determine if remediation is feasible.

Alfalfa requirements Site problem Remedy Comments
Unrestricted rooting depth, at least 3 ft.
  • Hardpan, compacted soils
  • Deep ripping
---
Suitable soil type
  • Sandier soils require irrigation every few days.
  • Clayey soils may have poorer aeration.
   Alfalfa grows successfully on a range of soil textures, but seems to do best in sandy loam to clay loam soils.
Uniform soil texture through soil profile
  • Layered soil profile, hardpan
  • Mixing
---
Level land for proper irrigation and water penetration
  • Uneven topography, ditches
  • Leveling the field appropriately for the irrigation system
---
Proper drainage
  • Waterlogging
  • Runoff
  • Precise field leveling
  • Install drainage tiles
  • Consider tail water return system
Poor drainage can lead to runoff and water quality problems.
Proper nutrient levels. P, K commonly deficient
  • Nutrient deficiencies such as P, K
  • Fertilize if soil tests show deficiencies
---
pH between 6.2 and 7.5 to favor N-fixing Rhizobium bacteria
  • Low pH
  • High pH
  • Low pH: lime the soil
  • High pH: reclaim (see sodic soil below)
---
Proper salinity level:
ECe <=2.0 mmhos /cm
  • Saline soil
  • Reclaim: leach excess salts below the root zone
 Sites with excessive salts require major modifications that can be expensive.
Proper soil Na level
  • Sodic soil
  • For soils w/ CaCO3: use soil amendments with S
  • For soils low in Ca: apply a Ca source, such as gypsum
 Sites with excessive Na require major modifications that can be expensive.

preplanting techniques

  • Pre-irrigate the field and cultivate germinating weeds.
  • Disc harrow, float, pack soil to build a firm seedbed.
  • Consider preplant herbicides.

Legend
  • P=Potassium
  • K=Phosphorous
  • --- = No information
  • N=Nitrogen
  • ECe=Electrical conductivity of the extract
  • Na=Sodium
  • CaCO3=Calcium carbonate
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Statewide IPM Program, Agriculture and Natural Resources, University of California
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