Maize (corn) and sorghum are C4 plants and Wikipedia lists the plant families which are C4 but people don't grow or eat most of the other C4 plants. I'd guess you'd need to look up the plants in each family to see if there is something you do eat or grow.

It does rain in central Texas and rainfall contains sodium (as a compound) that averages 7 to 14mg per liter, which varies throughout the U.S and higher in proximity to coastal areas. Average coastal areas vary between 14 and 28 mg/liter and Brownsville can contain as much as 28 to 61 mg/liter of rainfall. So you get plenty of sodium in what little rain you do get, and a lot compared to my area which barely contains 2 mg/liter. (There are maps showing average sodium levels in rainfall.) Your Irrigation water also contains Sodium unless it's somehow unique.

Texas ground water tests show Sodium levels (as a compound) quite high with 90% of 7700 wells tested throughout the state containing 20mg/liter or more, If you're concerned contact your water supply to ask about sodium levels because it varies by area. Sodium in pure form does not exist in nature and is always found as a compound so I'm confused why your soil test would test for sodium, and pure sodium isn't a salt but a metal. It's also part of a compound in rain and ground water so I'm even more confused why they'd test for something most plants do not need or use.

Could you be talking about total "Soluble salts" and confusing salts with sodium? A salt is any chemical compound that is composed of a positively charged ion and a negatively charged ion. A sodium ion has a positive charge (+1), and in a compound with a negative charged (-1) ion will be considered a salt. Chloride ion's are (-1) and sodium is (+1) so the combination is common table salt, but salts also form with other elements not containing any sodium. Potassium (+1) chloride (-1) so it's a salt, and Ammonium (+1) nitrate (-1) is also a salt, so not all salts will contain Sodium or even chloride.

Your total soluble salts are low because you use very little compound fertilizers which is good. If it was very high You'd need to leach out the salts for healthy soil and healthy plants, and I doubt you grow any coastal weeds or grasses of the C4 type with a high demand for sodium so everything is good.

here is a fertilizer salt index chart and even too much manure contains excess salts that can cause high soluble salt levels.

The Wikipedia article doesn't refer explicitly to any vegetable families that I recognize. Not very useful.

My irrigation/drinking water is 24 mg/L=ppm sodium. That's assessed quarterly, and seems to be a solid number. Somewhat higher than rainwater. I use far more of that than I rely on rainwater. I don't call that "plenty" of sodium, and neither does my soil test group. Seawater is a thousand times higher than that in sodium content.

As I said, research shows that sodium *is* something that many plants need and use. Especially C4 plants. I can supply research references if you like. But you can Google them and find them yourself.

I'm not confusing salts with sodium. Soil sodium largely comes from chemical salts that are dissociated in the soil moisture. Sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium bicarbonate and sodium carbonate - take your pick. My reference to "salting" plants was a little joke about applying sodium chloride. That salt is where you find conveniently soluble household sodium.

Um, nitrogen is always found in soil as a compound too, but they test for that.

That's true that maize and sorghum are C4. Apparently very few plants are C4, but the few that are are tremendously important commercially. Corn and sugar cane are among them. There is some experimentation with making wheat that is C4. C4 is photosynthetically more efficient (better productivity), more drought tolerant, and better suited to higher temperatures, so there is a lot of interest in developing that.

On further literature research, I'm seeing that bad things happen in C4 plants when the sodium concentration drops below 10-30 ppm. I'm looking at 56 ppm in my soil. So it would seem that I have quite enough sodium. That's a relief. I also now understand that the "Extremely Low" class in my soil test is an absolute scale, and does not mean extremely low compared to what is optimal. From the narrow perspective of avoiding overly saline soils, "Extremely Low" can be considered extremely good.

FWIW, my manganese is labelled "Very High" at 50 ppm in my test, but it's well understood that manganese toxicity doesn't set in until several hundred ppm. So these descriptive terms can be somewhat deceptive.