A section of a alfalfa farm soil is bad. It is told that the cause is salty soil. What can be done to fix the soil?
As requested by @csk , the source of the salt is: well, the land has been a salty desert and has been converted to farm land in a couple of farmer generations. This is as far as I asked local farmers!
First thing is to plot out the soil profile for the area. Remediation measures depend very much on what type of soil you have, whether clay, sand, silt or loam and what mixture of each. Clay will be very hard to work with, and remediation will be slow compared to sandy loam since the salt binds more closely to small particles. Sample the soil from many spots including those that appear to not have a problem.
If you find clay then consider improving the drainage in that area if possible by changing the soil profile, ie by building up the humus content or adding sand. Once irrigation water can flow quickly through the surface soil remediation will be quicker and more effective.
Also consider that there might have been an equipment malfunction at that spot, say a large spill of fertilizer which would result in high salt readings for that area.
Rain water and snow melt are reliably non-salty and with the passage of a few years could clear the problem if the soil is cooperative.
An answer according to @csk comments:
If you do a google search for "salt remediation" you'll find lots of different guides. Do you know what the source of the salt is? There may be different solutions for salt caused by salty groundwater versus contamination by fracking fluids or saline irrigation water.
This study discusses using salt-tolerant plants for remediation. This study has a good table on page 39 comparing the effectiveness of irrigation, tilling and several soil amendments
This report recommends watering the salty area; if done properly, the water dissolves the salt and moves it below the root zone. But the site must have adequate drainage, and you have to use non-saline water
One solution suggested by some local farmers is as follows:
Get chaff on the salty area and mix it with salty soil. Consider some watering afterwards. Watering should be done with non-salty water. Also, watering should be accompanied with proper drainage.
