# Onions and lime



## TxGypsy (Nov 23, 2006)

There was a thread on here a little while back(I'm too lazy to find it) where me and another person disagreed about putting lime on onions. You know how sometimes you just know something and your brain doesn't immediately pull to the front of your mind why you do it that way? Today at lunch I was eating a really good sweet onion. First thing that popped into my head is.....they must have really thrown the lime to this onion. That's when the lightbulb went on in my brain :bouncy: and I remembered why I add lime. I was beginning to think that it had burned out. 

One of the tiny little towns I grew up near was famous for it's onions. People would drive 50 miles or more to buy sweet Noonday onions. I think the little town claims to be the onion capital(why does every tiny town need a claim to fame?). The way they get the onions so sweet is to pour lots of lime onto our slightly acid soil(lots of pine trees). If they lime it correctly(far enough before planting, put on correct amount) the onions are almost sweet as an apple. As I recall....the land for the most part was a sandy loam.....also wonderful for growing roses.


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## SquashNut (Sep 25, 2005)

If your soil normally needs lime then, yes go ahead and lime the onion bed.
I lime in the fall, so lime has time to dissolve.
Beside the variety of onion, the important thing to growing sweet onions is moisture. last year was real dry here and our onions were hotter than normal.


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## Paquebot (May 10, 2002)

Lime is NOT what makes onions sweet. Sweetness and storage capability is determined by the sugar, sulfur and water content. Lime has absolutely nothing to do with the amount of sugar or sulfur content of an onion. Onions do best in a pH range of 5.8 to 7.0. Adding lime to soil 7.0 or higher would have an adverse effect on the harvest, not something for the better.
www.sweetonionsource.com/difference.html

Martin


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## veggrower (Jan 13, 2007)

Paquebot said:


> Lime has absolutely nothing to do with the amount of sugar or sulfur content of an onion. Onions do best in a pH range of 5.8 to 7.0.
> www.sweetonionsource.com/difference.html
> 
> Martin


You really have no basis for making an absolute statment such as this. How many acres of onions have you ever actually grown. I said it before and no doubt will have to say it again, the learning obtained simply from reading garden books and accepting all they say as fact is very limited compared to the learning obtained in actually doing. 

Onions are a large consumer of Calcium and Magnesium the 2 elements that make up dolomitic lime. You are missing that Calcium and Magnesium are both very important nutrients, and that lime does much more than just raise pH. 
The amount of lime necessary to raise the pH from 6.0 to 7.0 is HUGE. Also, you are not in a position to say how much lime will be too much without knowing the SMP buffer pH of a given soil.An example from my own fields:

My soil pH is 6.3, my SMP buffer pH is 6.6--it would take 2200lbs/acre of Ag lime to raise my soil pH from 6.3 to 6.4 and it would take almost 2 years for the pH change to fully take effect. I just had my soil limed at 2000lbs/acre because, while my pH is ideal my soil is *LOW IN CALCIUM* I didn't lime my fields to raise the pH, I limed the soil to increase the fertility.

My "Knott's Handbook for Vegetable Growers" shows the following:

Nutrient uptake for bulb onions in lbs/acre:

N:61 P:12 K:72 *Ca:8.5 Mg:11.2.*

You can see that onions uptake almost as much Ca and Mg as they do P.

Studies have shown that the addition of CaCO3 (ag lime) increases an onions uptake of P more than adding Phosphorous fertilizer. Ca plays many different roles in plants, increasing their vigor, rate of photosynthesis, cold tolerance (very important for overwintered sweet onions). Onions grown on soils low in Calcium could indeed have increased sugar levels by the addition of Calcium in the form of lime to the soil. A more vigorous, healthier, plant with increased photosynthesis will develop more sugars than a plant with lower photosynthesis. Pretty simple, really. Sugar is a carbohydrate, how does a plant make carbohydrates--photosynthesis.

Ca deficiency in onions is characterized by: leaf tip dieback on young leaves, dry or brown tissue in the bulbs, limp leaves, apparent root injury. If the roots and leaves of a plant are not functioning at an optimum level, guess what, less sugars produced.

Mg deficiency in onions is characterised by: leaf dieback, foliage dies premature, growth is slow

In the 'Vidalia' growing regions of Georgia, they regularly lime with dolomite.

The following is a study by Dr. T.L. Jackson, a soil scientist at Oregon State University. It is titled "Lime and fertilizer effects on overwintered onions." I was conducted in the Willamette Valley of Western Oregon just 20 or so miles north of me. They added 0,2,4,6 tons of lime/acre on the different test plots. The results show a large increase in yield and yield quality with the addition of lime.


Results and Discussion

1983.
Application of lime significantly increased onion stands, total onion yield, yield of #1 bulbs, mean bulb weight, and number of bulbs harvested (Table 1). Stand counts were made in April 1983, too late to determine whether the lime application enhanced onion germination and emergence or enhanced survival by increasing the growth rate of seedlings. Previous experiments on Willamette soil indicated that liming increases seedling emergence of onions and several other small seeded vegetable crops. Since the application of lime also visibly stimulated early plant growth (no measurements recorded), enhanced winter survival of larger seedlings also may have contributed to the effect of lime on onion stands. Of the subplot treatments, only N application affected stands, with a small, but statistically significant, increase in stand on plots which received no spring fertilizer. Since no stand counts were made before application of the first subplot treatments, it cannot be determined whether spring fertilizer application actually caused some stand reduction or the stand differences reflected existing variability within main plots.

Most of the stand and yield response to lime occurred with application of only 2 tons/acre; however, further significant increases in yield and number of grade #1 bulbs were obtained at 4 tons/acre (Table 1). Leaf tissue of plants grown on limed soil contained significantly higher concentrations of P, K, and Ca, and significantly lower concentrations of Zn and Mn than did leaf tissue grown on unlimed soil (Table 2). Since P levels were quite low compared to reported values and were increased 24% with application of 4 tons/acre of lime, much of the yield response to lime might be ascribed to increased P availability. However, increased K and Ca uptake or reduction of Mn toxicity may also have been involved in the lime response.

Application of spring N fertilizer, when averaged across lime, P, gypsum, and form of N applied, significantly increased total and #1 yields and bulb weight (Table 1). There were no significant N x lime interactions, and highest overall yields (30-33 tons/acre) were obtained with combinations of the highest rate of lime and spring application of either ammonium nitrate or ammonium sulfate. Application of spring N increased leaf tissue N, Zn, and Mn concentrations. Undoubtedly, the yield response to N was primarily attributable to increased soil N supply. The increase in tissue Zn concentration may also have played a role since Zn concentration of plants which received no spring fertilizer application was low compared to values reported in the literature. The increase in leaf tissue Zn and Mn concentrations with spring N application may have been caused by a temporary localized decrease in soil pH after application of the acidifying N fertilizers.

Within the subset of plots receiving a spring application of fertilizer, there was a trend toward higher yields and mean bulb weights with ammonium sulfate as N source (Table 1). These differences were never significant at the 95% level; however, the increase in total yield was significant at the 90% level. Leaf tissue N levels were slightly higher with ammonium sulfate as N source, but other tissue elemental concentrations were not significantly affected by N source (Table 2). Certainly, it does not appear necessary to provide NO3-N to assure good onion yields.

Within the subset of treatments receiving a spring application of ammonium nitrate, application of concentrated superphosphate did not affect overall yields but did slightly increase mean bulb weight (Table 1). There were no significant P x lime interactions. Application of P had no effect on leaf elemental concentrations (Table 2). Since P had no effect on tissue P levels, it is evident that the surface application did not bring the relatively insoluble P into sufficient contact with the root mass, or that some other factor prevented effective uptake. Lack of P uptake from the fertilizer probably precluded any yield response. However, since the winter and spring were unusually mild, any P effect on yield may have been masked by better than normal spring growth on all plots.


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## Paquebot (May 10, 2002)

veggrower said:


> You really have no basis for making an absolute statment such as this. How many acres of onions have you ever actually grown. I said it before and no doubt will have to say it again, the learning obtained simply from reading garden books and accepting all they say as fact is very limited compared to the learning obtained in actually doing.
> 
> Onions are a large consumer of Calcium and Magnesium the 2 elements that make up dolomitic lime. You are missing that Calcium and Magnesium are both very important nutrients, and that lime does much more than just raise pH.
> The amount of lime necessary to raise the pH from 6.0 to 7.0 is HUGE. Also, you are not in a position to say how much lime will be too much without knowing the SMP buffer pH of a given soil.An example from my own fields:
> ...


I also do not believe that you are in any position to know what the pH of TxGypsy's soil is. And yet you make it sound as if it's the same as what you have. What the pH of your soil or mine has no bearing on the question. The original post on this thread implies that the sweetness of an onion is due to the lime and that is incorrect. I linked to a site which explained what causes one variety to be more or less sweeter than another. Although calcium and magnesium are important for healthy growth of an onion plant, they are are NOT what causes one onion to be more or less sweeter than another.

It also matters not if a person grows acres of onions or 1 one onion. The results are the same. 

Martin


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## SquashNut (Sep 25, 2005)

Paquebot said:


> I also do not believe that you are in any position to know what the pH of TxGypsy's soil is. And yet you make it sound as if it's the same as what you have. What the pH of your soil or mine has no bearing on the question. The original post on this thread implies that the sweetness of an onion is due to the lime and that is incorrect. I linked to a site which explained what causes one variety to be more or less sweeter than another. Although calcium and magnesium are important for healthy growth of an onion plant, they are are NOT what causes one onion to be more or less sweeter than another.
> 
> It also matters not if a person grows acres of onions or 1 one onion. The results are the same.
> 
> Martin


That's why I said "if" your soil normally needs lime.
I am sure there are parts of our country where they would cause problems by adding lime.
Now I need to do the math and figure out how much lime at 2000 pounds to the acre works out to treat 100 square foot. Just to double check my math any one know?


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## MELOC (Sep 26, 2005)

about 5 pounds.


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## Paquebot (May 10, 2002)

43,560 sq. ft. per acre. If your soil test calls for application of lime at the rate of 2,000 pounds per acre, it's 4.6 pounds per 100 sq. ft.

Martin


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## SquashNut (Sep 25, 2005)

I am one of those nuts who don't do soil tests. My garden grows well enough with out one. Call me crazy.
Ya thats about what I got on the math too.
But kinda figured I better have some one check my math , just in case cause I only grow about 100 foot of onions and wasn't sure if I could figure it out with out help.
My guess 4.6 pounds is about a 13 oz. coffee can of dolomite lime, right.


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## rwinsouthla (Oct 24, 2005)

SquashNut said:


> I am one of those nuts who don't do soil tests.


Me too.


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## TxGypsy (Nov 23, 2006)

Thanks for the very informative answer veggrower. I never knew the technical reason for adding lime. I just knew that it worked. A word to the wise, or those that want to become wise.......find an old timer in your area with a nice garden and see if you can get them talking about what they do in their garden. This will serve you better than all the garden books and expert opinions that are out there. They may tell you something that flies in the face of things you have read....try it anyhow. Variety is the spice of life. If nobody ever experimented and did things differently we would never have new discoveries.

My advice(or anyone elses) will be based on my personal experience. As a simple fallable human being....I only have my experience to draw upon. I would not presume to put myself forward as an all knowing expert. Conversely I try not to speak about things that I have no knowledge of. The views I express are honestly presented in an effort to share my passion of gardening and pass on what little knowledge I might possess. I also hope that I might be able to learn a thing or two at the same time.


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## suburbanite (Jul 27, 2006)

Is the lime used with onions for pH adjustment or calcium enrichment?

My soil has a pH between 7 and 7.4; my city water tends to run slighly basic as well, and has a lot of dissolved minerals in it, including calcium. Dunno if the calcium is bioavailable though.


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## Paquebot (May 10, 2002)

suburbanite said:


> My soil has a pH between 7 and 7.4; my city water tends to run slighly basic as well, and has a lot of dissolved minerals in it, including calcium. Dunno if the calcium is bioavailable though.


You know what the pH of your soil is. If you did not, and had asked a question about how to make your onions sweeter, would lime have been the accepted answer? If you had then applied lime and had a negative affect on the overall health and harvest, would there be some claiming that you apparently did not apply enough lime and call for more? Probably! If a test showed that you definitely needed calcium in 7.4 pH soil, lime would not be the recommended solution. 

It amazes me that there are so many gardeners who don't have a clue as to what they have. They won't spend a dime to have their soil tested but will spend many dollars to correct a phantom problem. By contrast, you're not going to find a single crop farmer who does not know his soil. Those who don't know and don't care are those who are happy with whatever harvest they get. If they were to suddenly discover that they could have been getting perhaps 50% more, then that's bad for their ego. So, they muddle along as best they can and are happy with the status quo, never getting any better. They simply adapt a monkey see, monkey do attitude and find all sorts of other excuses when one monkey gets more than the other!

Martin


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## TxGypsy (Nov 23, 2006)

Paquebot said:


> You know what the pH of your soil is. If you did not, and had asked a question about how to make your onions sweeter, would lime have been the accepted answer? If you had then applied lime and had a negative affect on the overall health and harvest, would there be some claiming that you apparently did not apply enough lime and call for more? Probably! If a test showed that you definitely needed calcium in 7.4 pH soil, lime would not be the recommended solution.
> 
> It amazes me that there are so many gardeners who don't have a clue as to what they have. They won't spend a dime to have their soil tested but will spend many dollars to correct a phantom problem. By contrast, you're not going to find a single crop farmer who does not know his soil. Those who don't know and don't care are those who are happy with whatever harvest they get. If they were to suddenly discover that they could have been getting perhaps 50% more, then that's bad for their ego. So, they muddle along as best they can and are happy with the status quo, never getting any better. They simply adapt a monkey see, monkey do attitude and find all sorts of other excuses when one monkey gets more than the other!
> 
> Martin



I didn't notice an answer in your response to suburbanites question. Did you have an answer?


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## TxGypsy (Nov 23, 2006)

suburbanite said:


> Is the lime used with onions for pH adjustment or calcium enrichment?
> 
> My soil has a pH between 7 and 7.4; my city water tends to run slighly basic as well, and has a lot of dissolved minerals in it, including calcium. Dunno if the calcium is bioavailable though.


I cannot say for absolute sure, but I'd say it was to help both. Probably a bit more on the calcium enrichment side than for ph. 

You know I've wondered the same thing about dissolved minerals in water :shrug: In my current location our main problem is that along with lots of dissolved minerals we have a LOT of dissolved salt along with it. I'll be doing my best to use harvested rainwater. You might also look into that. Rainwater catchment is such a sensible thing that it surprises me more areas of the country don't do it. Hopefully someone that is more of a chemist will have an answer.


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## Paquebot (May 10, 2002)

TxGypsy said:


> I didn't notice an answer in your response to suburbanites question. Did you have an answer?


I did answer it! I stated that lime would not be used to adjust pH of her soil which is already high at 7.4. Lime is used for pH adjustment of acidic soils, not alkaline. Were Suburbanite to have a test which indicates calcium deficiency combined with already high pH, that would call for a different source of calcium. For a simple garden, most convenient organic source would be bone meal.

Martin


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## Paquebot (May 10, 2002)

Texas A&M University experts were the ones who developed the famous supersweet 1015 Texas Grano onion. Here's a direct quote from them which explains why you may be creating one problem by attempting to correct something using the wrong method:

"If soil pH is high or alkaline, essential elements such as phosphorus and iron become unavailable for plant use even though they may be present in the soil."

Martin


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## suburbanite (Jul 27, 2006)

Thanks Martin. I've been using sluggo for snail deterrence so I suspect that my iron and phosphate levels are high enough to overcome the effect of my slightly basic (alkaline) soil.

I have used sulfur and peat as amendments before, to add acidity/decrease pH.

I think as a rule of thumb east of the Rockies you're acidic and west of the Rockies you're alkaline, where soil is concerned. Unless you're in a pine or fir forest, in which case you're acidic.


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## SquashNut (Sep 25, 2005)

we're in the Rockies, The soil here is acid. The nursery owner here told me to look for things like moss in the lawn and slugs to indicate acid soil ph. She also told me to use some wood ashes and dolomite lime stone.
The older gardener behind me told me to use gypsum. Then i was told by the nursery owner I would wreck the soil with gypsum.
i just look at my plants they tell me what kind of soil I have. try to keep good records too. So I can rotate soil amendments and crops. It's working so far.


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## suburbanite (Jul 27, 2006)

I have moss and slugs and a soil test kit which indicates that my soil is between pH 7 and 7.4

You can get a pH test kit that also covers nitrogen and phosphate for less than $10 at most hardware stores.


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## veggrower (Jan 13, 2007)

Paquebot said:


> Onions do best in a pH range of 5.8 to 7.0. Adding lime to soil 7.0 or higher would have an adverse effect on the harvest, not something for the better.
> www.sweetonionsource.com/difference.html
> 
> Martin


You are so clueless on onion production yet you pass yourself off a the onion expert.

My onion pedigree: I grew up in Malheur county Oregon--at one time fully 25%of the onions grown in th United States came from the Treasure Valley area where I grew up. I don't know the current numbers but they are significant still. I grew up around onions and I know those soils. I have many friends who are life long onion growers. I have farmed the great Sherwood Oregon peat/muck onion flats. Again, talking with life long onion growers weekly. I have grown a few acres of onions myslef, with great results--not thousands of acres like my budies but acres.

The Pacific NW states of Or Wa Id are the 3 largest onion growing areas in the US. Most of thoe onions are grown in the arid desert areas of E/Central Was/Or and Western Idaho. * Those great onion growing areas of this country have naturally alkaline soil--the pH in the inion fields out there run typically 7.5 and THEY STILL ADD CALCIUM TO THE SOIL IN THE FORM OF GYPSUM!!!!.*. I just verified this with a OSU extension agent who was a field man for a large onion company in the Treasure Valley for years and is considered the goto guy for Alliums in this state. Again another firend of mine. 

Why would professional onion growers add calcium to the soil with a pH of 7.5 if it would lower the yields as you emphatically state? Are they wrong and you are right? I don't think so.

Every commercial production guide for onions put out by ag universites of the major onion producing states show the ideal range as 6.0-6.6 not 5.8 on the low end. U of Ga states 6.2-6.5 recommending dolomite if it falls below 6.2. They all recommend lime if the pH fall below 6.0 not 5.8 At 5.8 you are going to have Manganese toxicity proble showing up reducing your yields.

In another thread you claim that onions have to be fall planted to reach larges size--WRONG! Most of the huge onions grown in this country are direct seeded between Feb and May. The ones grown overwinter are time to hit the June market when the [prices are highest. They are normally direct seed in the spring to avoid the cost of keeping them weed free for 5 or 6 extra months.

Onions are a leaf crop not a root crop. They want a leaf crop fert not a root crop fert. You claim to have formulated the perfect onion fert--there is no such thing. There is no one perfet\ct fert. Onions have a shallow coarse roots system that is inefficient. They like a little fert preplant and then sidedressing or foliar feeding or fertigation throughout the growing season.

You can continue to operate under your misinformation on onions, it's not worth my time to try to change your mind. I will post the correct info on onions to help out others.


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## Paquebot (May 10, 2002)

> THEY STILL ADD CALCIUM TO THE SOIL IN THE FORM OF GYPSUM!!!!.[/B].


Gypsum is NOT lime, in case you didn't know that! Gypsum contains up to 15% or more sulfur. Sulfur is used to LOWER pH of alkaline soil.

Martin


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## Paquebot (May 10, 2002)

veggrower said:


> .
> In another thread you claim that onions have to be fall planted to reach larges size--WRONG! Most of the huge onions grown in this country are direct seeded between Feb and May. The ones grown overwinter are time to hit the June market when the [prices are highest. They are normally direct seed in the spring to avoid the cost of keeping them weed free for 5 or 6 extra months.


In case you aren't familiar with the location of the US states, Texas is not near Oregon. Texas is in the short day zone and Oregon is in the long day zone. 1015 Texas Grano was so named due to the best planting time and it still applies. Whatever planting schedule applies to growing onions in Oregon has little bearing on when to plant onions in Texas.

Martin


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## moonwolf (Sep 20, 2004)

TxGypsy said:


> Today at lunch I was eating a really good sweet onion. First thing that popped into my head is.....they must have really thrown the lime to this onion. That's when the lightbulb went on in my brain :bouncy: and I remembered why I add lime. I was beginning to think that it had burned out.
> 
> .


I'm neither a commercial grower, nor an onion expert, but I have grown many types of onions. It's the variety chosen that determines if the onion will be big, small, sweeter, or more pungent, red, white, yellow, etc. In other words most of that is genetically determined IMHO. I've grown Kelsae Giant onions and watered them regurlarly. They were very sweet and very big. If neglected where weeds and more dry conditions were allowe, the same variety was stunted and not as sweet. On the storage onions I like the ones that are a late harvesting one that has a neck that dries down and the onion 'harden's propery for storage. On red onions, I choose one that is sweeter by it's 'type name' and one that is more pungent which stores longer. I don't believe liming is what makes the onion 'sweeter'. If it's a 'sweet' variety for your season length, than it should be sweet with proper moisture levels and good 'normal' soil for onion growth in general. If it's going to be a pungent onion to begin with, adding more lime won't 'sweeten' it. 
I agree with Paquebot that it depends where you are growing onions for daylenght as well as soil type. The best thing I've EVER applied to growing onions to make them 'better', regardless of 'type' was to have good compost availalbe to add. I also did well with greenmanure plowdown prior to planting, and loose soil, but not so much for onions does that matter as for some other crops.


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## Paquebot (May 10, 2002)

veggrower said:


> You are so clueless on onion production yet you pass yourself off a the onion expert.


I do think that it's an honor that someone recognizes me as an onion expert. I hadn't ever proclaimed myself as that and am happy to see that I'm coming across that way!



> My onion pedigree: I grew up in Malheur county Oregon--at one time fully 25%of the onions grown in th United States came from the Treasure Valley area where I grew up. I don't know the current numbers but they are significant still. I grew up around onions and I know those soils. I have many friends who are life long onion growers. I have farmed the great Sherwood Oregon peat/muck onion flats. Again, talking with life long onion growers weekly. I have grown a few acres of onions myslef, with great results--not thousands of acres like my budies but acres.


What does this have to do with the taste of onions in Texas?




> Why would professional onion growers add calcium to the soil with a pH of 7.5 if it would lower the yields as you emphatically state? Are they wrong and you are right? I don't think so.


Their soil is alkaline but it is not from being caliche as is common in the Southwest. Since they have a shortage of calcium, it must be added in a form which will not increase the pH. That's accomplished by gypsum. 



> Every commercial production guide for onions put out by ag universites of the major onion producing states show the ideal range as 6.0-6.6 not 5.8 on the low end. U of Ga states 6.2-6.5 recommending dolomite if it falls below 6.2. They all recommend lime if the pH fall below 6.0 not 5.8 At 5.8 you are going to have Manganese toxicity proble showing up reducing your yields.


Nowhere in this thread has anyone advocated NOT adding lime to soil below 6.5 ph.



> In another thread you claim that onions have to be fall planted to reach larges size--WRONG! Most of the huge onions grown in this country are direct seeded between Feb and May. The ones grown overwinter are time to hit the June market when the [prices are highest. They are normally direct seed in the spring to avoid the cost of keeping them weed free for 5 or 6 extra months.


One of the largest, if not the largest, onion plant suppliers ships their short day varieties during the period Nov-Apr. Some of those varieties are 1015Y Texas Supersweet, Yellow Granex, White Bermuda, and other large-bulbed varieties. Their plant shipping dates do not seem to blend well with the Feb-May seeding period claim.



> Onions are a leaf crop not a root crop. They want a leaf crop fert not a root crop fert. You claim to have formulated the perfect onion fert--there is no such thing. There is no one perfet\ct fert. Onions have a shallow coarse roots system that is inefficient. They like a little fert preplant and then sidedressing or foliar feeding or fertigation throughout the growing season.


That was an interesting revelation. Even I am trying to locate that fertilizer formula that I supposedly have perfected. Where is it? What is the NPK value? What's the application rate? Since it's never been mentioned on this or any other forum, it obviously only exists in your imagination. 



> You can continue to operate under your misinformation on onions, it's not worth my time to try to change your mind. I will post the correct info on onions to help out others.


Good! I will continue to do my very best to assure all gardeners that they may enjoy the very best onions that their can possibly produce. At no time will I ever give advice which will lessen their opportunities to do so. 

An added comment:
To first help others, learn how to read their posts and find out what they need. Take the time to explore the possibilities that what works for you may be the exact opposite of what they need. If you take the stand that the only things that apply are those which work in your tiny little part of the world, then you will be the cause of more damage than help. 

Martin


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## turtlehead (Jul 22, 2005)

suburbanite said:


> You can get a pH test kit that also covers nitrogen and phosphate for less than $10 at most hardware stores.


This one cost me $3.24 last year. It tests for N,P,K, and pH.


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