Released: March 28, 2005

Oceans, Gardeners Still Sowing Salt

MANHATTAN, Kan. – “Salting the soil” and “sowing salt” are phrases deep in almost every culture’s history. They’ve come to mean deliberately ruining something that was good or needed.

Nowadays, the actual sowing of salt can result from acts of nature, as when the tsunamis hit Southeast Asia last December, spreading ocean water over huge stretches of farmland. Ironically, however, it also can happen among responsible gardeners.

“Sometimes we see salt accumulate because gardeners are irrigating from a well that has water with a high salt content. Sometimes we see it where people have been using salt to melt winter ice. Most often, though, we see salt build up as a result of how people are fertilizing,” said Chuck Marr, vegetable crops horticulturist with Kansas State University Research and Extension.

Those applying the fertilizers may be using manure from animals that had salt in their rations, he said. They may simply be fertilizing too much. Or, they may be creating areas of salt buildup by applying fertilizer unevenly

If the mistakes were bigger, they’d probably give plants obvious fertilizer-burn injuries.

As a buildup in the soil progresses, however, sometimes the only real symptom is poor plant performance, Marr said. The vegetable and fruit plants most sensitive to salts in soils include beans, carrots, onions and strawberries. Moderately sensitive plants include the lettuces, peppers, radishes and turnips. Among the least affected plants are beets, squashes and tomatoes.

“Fortunately, the good rainfall we had this winter probably reduced some of the potential for salt injury in many areas. The fact is, however, too many gardeners use manures without knowing what those natural products contain. Too many apply commercial fertilizer without knowing whether it’s really needed. And, most gardeners have to fight the tendency to think, ‘If a little is good for the garden, a lot should be even better,’” Marr said.

Salty soil doesn’t taste salty. It doesn’t always form a whitish precipitate around high-salt areas that have been watered. But, a simple soil test can provide the needed answers for gardeners who worry that salty soil could be making plants perform poorly.

“You have to request a salt analysis, though, since that’s usually not included in a routine garden soil test,” Marr said. “If you suspect your well may have some salt accumulation, you can submit a water sample, too. Your local Extension office can tell you how to take good samples. If you like, it also can forward either water or soil to K-State’s Soils Testing Lab.”

Getting rid of salts isn’t so easy. Leaching is the only way gardeners can remove them from soil – just as they do with houseplants, the horticulturist said. Outdoors, this means watering the soil excessively – not fast enough to cause runoff away from the affected area, but deeply and often enough to move salts down through the soil profile, below the “grow zone.”

“Unfortunately, Mother Nature will have to do the job in Southeast Asia – which, despite the region’s high rainfall, could take a while,” Marr said.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward
kward@oznet.ksu.edu
K-State Research& Extension News