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Whidbey Island

Western Laboratories suggests the ideal is 0.8 - 1.2 ppm. At the GPC online seminar in 2021 one of the heavy hitters suggested boron levels should be as high as 5 - 6ppm, if I heard right.

Any suggestions or recommendations for the correct level of boron to be aiming for in the soil? Thanks.

3/26/2022 7:05:11 PM

Deer Park, WI

Here's the challenge with boron...along with nitrogen and sulfur, they are the three nutrients that are "mobile" in the soil. This means every time water is applied, these nutrients move with the water. As such, it is nearly meaningless to try and measure them on a soil test, as you are only getting a snapshot of what is present at that very moment. By the time the next rain or watering event happens, the levels have changed.

Another challenge with boron is that it operates in a very narrow band of sufficiency. Below 1ppm can lead to signs of deficiency. above 4ppm can lead to signs of toxicity. That's a really tight range.

Organic matter serves as a reservoir for boron. Those of you running 5+ OM% probably have plenty to meet plant needs, assuming it is being released by microbes mineralizing the OM.

If one felt they needed to apply boron, 1 pound of Borax, the same stuff in the laundry detergent aisle, per 1000sq ft, will provide 2ppm of boron. Just make sure if you apply it, you do so as evenly as possible, then incorporate well. Boron hotspots can nuke plants/roots/seeds.

More on boron and application rates, as well as commentary on soil test interpretation and application rates are found in my soil test guide on the SCGA website:

https://www.stcroixgrowers.org/collections/how-to-guides/products/giant-pumpkin-growers-guide-to-interpreting-soil-tests-managing-fertility

3/27/2022 1:26:54 PM

Whidbey Island

Thanks! Great info.

3/27/2022 1:37:09 PM

Lymington UK

Nail & Head Joe.
Nitrogen is the hardest to get right for sure. Our labs say we should have 101ppm but we try to do the impossible and aim for 90 ppm.
If we get over 101ppm we tend to have a lot of snapped side vines
Sulphur is a rather strange beast and our labs say we should aim for 10ppm. We've had 70ppm in the past and still had leaf samples back showing deficiency.
Then we get to Boron and our labs suggest we need 2ppm.
In the case of Boron the labs probably think we're growing commercial field pumpkins and not something that grows the size of a small child a day.
To get the huge amounts of water the pumpkins need huge amounts of calcium and to get calcium they need the Boron.
We like to aim for 4 or 5ppm and have had no problems with it slightly higher.
Like Joe says, these elements are extremely difficult to control without numerous samples.
From the top of my head 8oz Borax raises our soil by about 1ppm.
Ian

3/27/2022 4:46:19 PM

Lymington UK

I forgot to say. We dissolve Borax in hot water and then put it through our drip system which is extremely accurate

3/27/2022 5:06:05 PM

Deer Park, WI

awesome commentary, Ian. Thanks for chiming in. Fascinating observation on nitrogen. 90 ppm translates to 180lbs/acre, roughly the same target I feel is necessary to grow a contest winning giant. More than that...brittle vines that reach for the sun...less than that we are likely leaving vegetative and reproductive growth on the table. I'm with Ian here..fine tuning nitrogen is probably the most challenging aspect of soil fertility, regardless of the crop being grown.

In order to improve on nitrogen management, I'm diving deep into the Haney soil test. Looking closer at C:N ratios and measuring the water-extractable components of carbon and nitrogen. I think there's answers within this data. More to come on this.

3/27/2022 5:59:08 PM

Brooktondale, New York

Useful...very useful. Thank you fo the exchange of hard earned knowledge. I genuinely appreciate your transparency. I wish you the best for the coming season.

3/27/2022 10:15:48 PM

Brooktondale, New York

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3/27/2022 10:16:31 PM

Kutztown, PA

Joe,

Based on a soil Boron level of .7 and a extractible/solution boron of .5 with calcium in the 3000's should I be adding Boron? Thanks for your answer in advance.

4/19/2022 4:18:33 PM