Pear orchard Ph adjustment

kokos(6a)December 22, 2010

I received some advice from folks on here that pears can suffer from chlorosis on alkaline soils. The pears do not show any symptoms of suffering but it can be not visible some say. My ph is 7.7 and I have a few pears planted in this soil containing Very High levels of Calcium. How much Sulfur or Iron Sulphate do I need per pear tree to knock the ph levels down 1 point to lets say 6.7?

How long does the Sulfur effect last for, does the ph eventually creep back up to its natural level after a while?

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Michael

Kokos: How old are your pear trees? All 3 0f mine started showing chlorosis in their 3rd leaf. To battle the chlorosis I started 2 years ago with using ammonium sulfate for the N fertilizing. too darned bad I didn't start with sulfur before the mulch as I discovered the sulfur has to be in contact with the soil to be converted to sulfuric acid. I've also tried foliar apps. of Iron in the Spring with no observable effect. This Spring I plan to use chelated iron, which is expensive, but it can be fertigated through the mulch which I plan to maintain. Sequestrene Fe 138 is the only chelated iron I know of that works on the alkaline soils. There are other chelated irons but they do not use the proper chelator (EDDHA)for alkaline and calcareous soils and will be ineffective. Some products contain Sequestrene Fe 138. If you do use Sequestrene Fe 138, don't leave it lying around on the soil surface as it can be photodegraded rapidly.

As far as Sulfur additions go, add elemental sulfur (90 or 99% sulfur material) annually at a rate of 6 to 10 pounds per 1000 square feet of area. Test the soil occasionally and stop adding sulfur when pH has reached desirable levels. Due to the large amount of free lime in the soil, yes, you can expect the pH to creep back up with time requiring the need to apply sulfur to drop the pH back down.

Can't say how long the sulfur addition's effect will last, has everything to do with your soil's buffering capacity, choice and use of fertilizers and whether or not you add more free lime via irrigation.

Oh BTW, get your soil tested included for micros., you may have plenty of micros present and won't need to add them, just make them available by lowering the pH.

Oh, and yes, your trees an be deficient without showing signs of it in the foliage.

Do you ever have to irrigate your trees, if so, how is your water quality with respect to pH and Ca?

    Bookmark   December 22, 2010 at 10:20PM
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kokos(6a)

thanks Mike. I irrigate the trees only during summer months, don't know the water quality though. The Pear trees will be entering their 3rd leaf next season(Spring 2011)

Soil test was done, outcome.......
Phosphorous is very low!
Magnesium is very low
Boron is Low
Iron High
Calcium is Very High

    Bookmark   December 23, 2010 at 2:15PM
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kokos(6a)

by the way regular sulfur(90%) does not work to lower ph on alkaline soils, it has to be in the form of Iron sulphate?

    Bookmark   December 23, 2010 at 2:17PM
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Michael

Yer welcome Kokos: Regular sulfur in fact will work to lower pH if in contact with the soil, preferably, incorporated to a greater or lesser extent. The problem with poor schmucks like you and I, having soils with high "lime" content, is that it takes a lot of sulfur compared to low lime soils to drop the pH; and of course, there will always be plenty of lime in the soil requiring subsequent additions over time as the pH will always want to revert to it's native state.

Good news on the Fe.

Mg - you might want to have the lab that did the testing get you a recommendation on that, maybe you have enough, maybe not. Don't listen if they tell you your Ca:Mg ratio is out of whack, the only problem MAY be not enough soil Mg for your trees.

P - good luck finding recommendations for your soil based on the soil test results(Mg too) growing fruit trees. Let me know if you find any.

    Bookmark   December 23, 2010 at 7:05PM
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kokos(6a)

So probably 1 kilo of sulfur per pear tree is useless. I don't have mulches on the trees just bare soil. Iron sulfate should be better than regular sulfur eh?

The soil test did not sat the Ca:Mg ratio was out of whack. The Mg and P levels were very low on their own.

    Bookmark   December 23, 2010 at 7:49PM
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kokos(6a)

what a fellow in Greece told me about European pears. I clipped it from my email.
What does he mean with "chlorosis"... that it is present during the first three years then it goes away after as the tree adjusts?
This is what he told me word for word:

"Concerning the pear trees it is proven that with soil pH 7.7 the fact of "chlorosis" appears at the pear trees for the first three years."

    Bookmark   December 23, 2010 at 8:09PM
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Michael

Hi Kokos: It appears that he is saying that for the first 3 years, chlorosis is present.

re: sulfur, if the root zones of the trees are small enough to allow an equivalent rate of 6-10 lb/1000 sq. ft. in the rooting zone then, your 0.5 Kilos should be fine. since your soil test indicates sufficient Fe in the soil already, I'd be hesitant to add more by using Iron sulfate. If you get too much Fe in the soil you could end up with a Zn and/or Mn deficiency in the plant even though there is adequate Zn and Mn in the soil. What is of paramount importance is that there is an adequate amount of the micronutrients in the soil (your test shows that for Fe) AND that they are available. Making the micros. available in your soil and mine is accomplished by lowering the soil pH.
The conversion from lb/sq ft to kg/sq meter is 1 lb/sq ft = 4.88 kg/sq meter.

    Bookmark   December 24, 2010 at 4:03PM
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kokos(6a)

thanks Michael357! Yeah the soil test indicates "High" for Iron in this farm located in Greece with the alkaline soil we are speaking of. The "High" reading is 10 ppm!
Not so "High" in comparison to my Soil I work with in Canada:(from where I am writing to you from now)

I have Very High Iron levels here(111 ppm)that I work with....but it has tons of manure added into the soil. This test was also 3 years ago. It must have come down a bit.

    Bookmark   December 24, 2010 at 5:13PM
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Michael

You are welcome Kokos: 111ppm, WOW! The Fe could have certainly been there without the manure depending on the soil's parent material, any hematite mines around your area?

    Bookmark   December 25, 2010 at 7:34PM
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kokos(6a)

No mines to my knowledge around here

    Bookmark   December 25, 2010 at 9:24PM
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