# Soil Ph and Annual Forages



## jdhayday (May 12, 2014)

I have soil tests showing a ph of around 5.1 It is irrigated land that I grow millets, oats, sorg/sud, ect. My local agronomist doesnt believe I would see any changes in production if I put out a ton or two of ag lime. Is this true, or would I benefit from a lime application? Thanks


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## Vol (Jul 5, 2009)

Maybe not for those specific crops you have listed, but if you decide to ever grow other crops like alfalfa that requires a PH of about 6, you will be behind the eight ball trying to boost it a full point in a short time. I would suggest you raise it to at least 5.5 or higher with a eye towards the future and saving you some time down the road if a change in crop production becomes a desire or priority.

Regards, Mike


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## rjmoses (Apr 4, 2010)

One or two tons on that low a PH will not make any significant difference. Without knowing your soil type, I would think about 4 tons would be a good start, if you incorporate it. And, its going to take a while for any lime to have an effect--probably two years.

Liming is a long term process. If you're top-dressing, you might lime two tons each for two years, wait a year, then do a soil test (the fourth year) to see where you're at.

Hope this helps.

Ralph


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## Hugh (Sep 23, 2013)

Bringing the PH up will lead to higher earthworm populations. They thrive in a neutral soil. The benefits of this will be better water penetration, better levels of organic matter, less soil compaction, etc. The economics of the matter is another concern. With this, you will need to do the numbers and make a guess.


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## vhaby (Dec 30, 2009)

Soil pH is only an indicator of acidity or alkalinity. Soil pH measured in water changes according to the ratio of water to soil used in the analysis. Most labs in the US use a 1:1 water to soil mixture in which to measure pH. When the water: soil ratio increases, measured soil pH also increases.

Regardless of the water: soil ratio used, as soil pH goes lower, soil acidity increases. At about pH 5.5 aluminum in the soil begins to solubilize and becomes more available as aluminum with three positive charges, or elemental aluminum in the soluble form. As soil pH goes much below 5.5, solubilized aluminum becomes more toxic to plant roots, burning the growing point of these roots and preventing root extension into the soil for water and plant nutrient uptake. Solubilized aluminum also precipitates plant available phosphorus in the soil, making it unavailable to plants.

Leaving acidity at a pH 5.1 in the soil surface risks crop yield loss because of reductions in water and nutrient uptake. Also, a pH of 5.1 in the surface soil can have the effect of increasing subsoil acidity. You need to apply limestone to this soil regardless of what your local agronomist thinks. Lime this soil to pH 6.2 for most crops. If you should want to grow alfalfa, lime the soil to pH 6.8 to 7.0.


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## Hugh (Sep 23, 2013)

I totality agree with vhaby. I always use distilled water at a 1 to 1 ratio with soil when testing pH and soluble salts.

Aluminum becomes toxic to many plants when the pH is so low that levels of this metal become soluble. However, the big question is one of money. How much will it cost to bring the pH of to healthy levels, and how much will you gain in production by doing so? For example, if it costs $100 to raise the pH to 6.5, and the production increase over 5 years will be 25%, then calculate the expense vs. the opportunity cost (loss) of interest or other investments earned over the same time period.

My philosophy is to get the best plant health, and mostly disregard the money question. In this case, I would lime the place like crazy.

These are questions that your checking account and reason can answer. If you are willing to invest in your land for the long term and if you are committed, then lime the soil. If you are casual about the whole thing, then just cut and bail what is there.

Sometimes the questions are economic, sometimes they are questions of pride, sometimes questions of science.


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## hog987 (Apr 5, 2011)

I had a talk with my friend the other day about changing soil ph with plants. We mostly talked about lowering the ph on some of my soil since it is high. He was having trouble remembering everything he learned 30+ years ago in university but did name a few plants that would work. But we didnt get to talking about raising the soil ph with plants. So what plants can grow to help raise the soil ph?


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## Dill (Nov 5, 2010)

Pine needles will make a soil more acidic, but judging by your pic, deep woods isn't a problem near you.


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## vhaby (Dec 30, 2009)

Sorry, but growing plants to raise the pH is a new one to me. Perhaps salt cedar that accumulates sodium at the base of plants would work, but I doubt that you would want to grow this arid adapted plant.


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## hay wilson in TX (Jan 28, 2009)

Probably 25 years ago on the Successful Farming Site two growers got to discussing lime and pH interaction.

One insisted lime was to modify an acid pH & the other insisted that the lime was to meet the plants need for calcium.

Actually both were correct.

If you do not mind a cure that is worse than the problem, Sodium will move the pH faster and further than calcium.
Less of a problem, magnesium will also move the pH up just not as fast of as far.

Lime rock is our dominant rock, here, & our soil is calcareous with a naturally high pH.

Too much calcium or too little calcium ether can be a challenge.
Learning to cooperate with ether soil is the key.

vhaby has as good a handle on both soils as anyone in Texas.


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