As growers, we know that it’s necessary at times to flush the root zone periodically to keep salts from building up in the profile and damaging crops.
For certain types of heavier soils with high salinity, irrigation management can become tricky and short, frequent irrigations need to be combined with flushing to make sure salts are pushed past the root zone.
Hortau Director of Grower Support Ben Smith answered the following question presented to him by a grower whose heavy clay soils had an EC of 9.2 dS/m.
Question: “If you have a tight clay soil with a high pH, part of your watering is to flush those salts out. So if you do that top-water, top-water, top-water, then down lower you’ve got all those salts in the root zone. How would you handle that?”
Hortau Director of Grower Support Ben Smith had this response:
“It depends on the severity of the condition.
For most soils in the salty area, you don’t need to worry about constantly leaching. It’s kind of an old idea to have a leaching fraction – or constantly moving water through. In most soils you just need to do it in the winter. In a case like yours, that’s severe enough that you would want to be doing more regular flushing events.
Now in that case, it depends on the length of time that you’re doing it. If it’s over a month that you’re flushing that water through, it’s probably not going to build up to a point where it’s an issue, but you definitely want to keep in mind to do periodic flushes where you really move the water through.
The thing to remember with it too is that when you’re leaching it’s better to do a series of frequent leaching events, rather than one long one. It kind of creates a plunger action in the soil that draws the salts out and moves them through.
The thing I’d watch out for is to do the leaching right before you’re going to put more fertilizer on, that way you’re waiting to the point where it’s depleted as possible and there’s lesser chance of losing nitrogen.”
- Approach to leaching salts from the profile depends on the severity of the situation
- In most cases, leaching salts in the wintertime is sufficient enough to prevent salt build-up in the soil during the next season
- A series of leach events is more efficient than one long one
- Important to leach prior to a nutrient application in order to maximize the availability of the nutrient