General Question

FireMadeFlesh's avatar

How long does the soil remain damaged after salting?

Asked by FireMadeFlesh (16598points) June 11th, 2016

Before modern times, an army facing defeat would often retreat, but burn their town and salt the earth around it, making the position unprofitable for the invaders. How long would the soil remain unsuitable for crops after this treatment?

Observing members: 0 Composing members: 0

14 Answers

Espiritus_Corvus's avatar

High salt content in the soil discourages plant growth. Armies would create buffer zones between their lands and the lands of their enemies by salting the earth and thus make that area unable to support a population of possible invaders. This would buy the salters time to arm in case of invasion. It was also an effective way to anhilliate an enemy threat completely by creating a famine and forcing the population to move on.

Different plants have different tolerances to salt in the soil. Finding a citrus tree alive and well on a piece of property in Florida is a good sign that the property hasn’t been inundated by salt water in approximately a century, because it takes about that amount of time for the sandy, porous soil of Florida to clear of salts to the tolerance levels of citrus. That is important to know when you live along a coastline known to be frequented by tropical storms.

Strauss's avatar

the best answer I can provide for the OP is: it depends on the soil and the de-salting method. The more clay is in the soil, the more difficult it will be to remove the salt.

If I wanted to prepare a previously such a piece of land for agriculture (garden or farm), I would prepare myself for some really hard work, to begin with. I would also resign myself to the fact that it might take several seasons to get the land to the point where it could be arable

I would first look at the soil composition itself. Some types of clay become impermeable to water with much lower concentrations of sodium, and rain can obviously wash salt rapidly out of permeable sand.

I would start with soil amendment. If the soil had a high clay content, then I would add organic material (loam, composted organic matter, manure from grazing animals, etc) and mix very well. I would then irrigate with the intent of washing the soil. Irrigation water, whatever the source (rivers, ponds, municipal sources, etc.) may contain some salt, and if not drained properly, will deposit the salt and other minerals upon evaporation.

CWOTUS's avatar

As I think on it now, and without having done any actual research into the topic, I question whether something has been lost in translation in this whole notion of “salting the earth”.

Armies moving on foot or even with the aid of pack animals and wagons have a hard enough time carrying the supplies that they absolutely need to support themselves, even when they are foraging off the lands and crops of occupied territories (whether “their own” or their enemies’ lands). As Napoleon observed, “An army travels on its stomach.” They certainly don’t carry around the tons – literally tons – of salt that would be required to effectively “salt the lands” that they give up to an enemy while in retreat. It’s just not possible. Salt is vital to armies on the march, but not in the quantities necessary to render large farm tracts unusable.

That is also quite aside from the fact that in ancient times salt itself was so valuable that it was offered as part of the inducement to warriors to fight, if we can believe the story so many of us have heard about how “salary” comes from the Latin word for the salt that was given to Roman legionnaires on the march – as pay. What army would – or could! – carry tons of a caustic mineral that would have to be guarded because of its value, and would then be somehow spread out on farmlands by soldiers in retreat. (Retreating soldiers do not generally have the time or patience to sow fields with poison – which they could more easily carry away themselves because of its value – and especially if they are retreating under assault and in fear for their lives. No officer yet born could make them, either.)

It may have been possible in some low-lying areas to flood farmlands with seawater, which would be quick and devastating for at least one full growing season – and which could add to a general famine of the enemy’s populace, along with the general mayhem of war. In that case, as @Yetanotheruser notes, it’s going to depend on the conditions: the soil itself and its internal drainage; the amount of fresh water the soil receives as rain which can either wash away or percolate the sea salt down below the root levels of crops, and the speed and efficacy with which the soil can be remediated.

ibstubro's avatar

I’m interested in the amount of salt required to “salt the earth” into a wasteland.

Like @CWOTUS, I have doubts about this scenario.

stanleybmanly's avatar

Doubt no more. Salting the earth was a common practice for the Romans in the days of the Republic. It was reserved for particularly obstinate folks who failed repeatedly to get the message that it was a bad idea to fk with Rome. Carthage for example, and the Jews apparently were rewarded similarly for their obstinate and extremely troublesome resistance in Judea. The thing to remember is that the term “salting the earth” doesn’t necessarily mean applying sodium chloride (though that will certainly do the trick). The application of anything that will render the land unable to support crops or foliage is “salting the earth”. The Romans were fond of lime for the purpose. The Romans were nothing if not pragmatic, and after the suppression of the revolt in Judea, the Jews were pretty much the last to receive “the treatment”. Instead of ruining productive land and rendering it uninhabitable, the Romans adopted the more sensible practice of settling retired soldiers and their families on conquered lands converting former trouble spots to grateful loyal and dependable lands of Roman citizens.

cazzie's avatar

It really is a matter of how long is a piece of string.

cazzie's avatar

But Hannibal got his revenge.

ibstubro's avatar

My dad always said “How long is a stick”, @cazzie, and he was a history teacher. ~

ibstubro's avatar

From Hannibal! if you care to enter the Twilight Zone.

cazzie's avatar

I haven’t looked it up, but one of the most famous saltings was Carthage. You might find information about how long it took before they should plant crops again. Just quickly looking at a Wiki article It says that Carthage was salted in 146BC and then the Romans rebuilt on the ruins of old Carthage 49BC to 44BC, so in this case, it may have taken 100 years.

susanc's avatar

I know we’re talking about deliberate salting, and I was interested in CWOTUS’s insight
about the cost of the salt itself and the cost of hauling it all over the place on your donkeys and camels. I can talk only about the fact that my flowerbeds are assaulted (that was a little pun)
a few times every winter by very high tides. I used to worry myself sick about this until someone pointed out that the high tides are caused partially by the unreasonable amount of rain we get here in the Pacific Northwest, and that that very same rain washes the salt back out of the soil in a jiffy.
Unfortunately for Carthage, North Africa is pretty darn dry.

cazzie's avatar

The sea salt pans in Malta are very old. I’ve seen them first hand. Really amazing. There are large salt pans in Tunisia so the salt didn’t have to brought that far. Carthage was a thriving major centre and Rome destroyed it because it was a rival for economic trade. North Africa wasn’t always as dry as it is today.

FireMadeFlesh's avatar

Interesting answers, thanks all.

Answer this question




to answer.

This question is in the General Section. Responses must be helpful and on-topic.

Your answer will be saved while you login or join.

Have a question? Ask Fluther!

What do you know more about?
Knowledge Networking @ Fluther