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Springfield, Missouri

Obviously soil is going to be our first limiting factor (besides seeds) in growing 1500+ pumpkins. I was looking at the Langley soil estimator and had a couple of questions.

The soil estimator helps calculate base-cation saturation ratios, however it does not give limits to any of the nutrients. For example: I found a soil tests in a diary where Sulfur 9 ppm, but someone else had Sulfur over 200 ppm.

Second the estimator does not take into account anion interactions. It would seem that excessive phosphate would inhibit the uptake of sulfate and vice versa.

My question in a nut shell is... what is the ideal range in ppm for each nutrient.

Thanks for the help!

11/8/2013 12:47:18 AM

Germany

What´s the ideal ratio (and the ideal total amount) of protein:carbohydrates:fat one should eat every day? The answer is:
It depends on where you live and what you do and where the nutrients come from and many many more other things.
Same with plants, the ideal ratio (and ideal total amount) of minerals isn´t a constant, it all depends on further environmental parameters.

11/8/2013 2:58:58 AM

Glosta

The Estimator is just that, an estimator. It is not a fix all cure all it was developed to give us an idea of what we add and how it stays in our soil. The estimator never tells you what to add it only returns the value of what you decide to add. So if you wanted to add a ton of triple phosphate it would just give you the amount of the nutrient you added, in PPM based on your plot size.

There is so much of a nutrient in an amendment so it can be tracked. The ratios on the estimator are a broad range and gives us a generalized idea of nutrient interactions. I didn't bother with sulfur and nitrogen as they are at high risk of leaching and therefore change at such a rapid rate.

There are a billion diffenrent processes and interactions going on in soil and the plant at once to try to pin them all down would confuse more than help.

As for an ideal range of PPM of each nutrient, Western labs did a study a few years back with some of the top growers and they gave a broad range for each nutrient. If you go to their tutorial page on their site you can find the info there.

There was a power point presentation on the GPC site that explained this and how to use the estimator.

11/8/2013 9:26:50 AM

Torrance, Ca.

With Bry's estimator, Westerns recommendations and a tissue test or two,,,,,,,,

Even the really slow people like myself,,, can be right where they need to be or pretty darn close during the growing season.

Even better, it will let you know what you added to much of or not enough of for the following season:)

11/8/2013 9:40:12 AM

Deer Park, WI

I have published general guidelines/ranges for soil nutrients in the "Giant Pumpkin Grower's Patch Guide" recently released, based on information compiled from soil test labs, studies of giant pumpkin patch performance & lab results, and book knowledge. The guide can be ordered from the SCGA website (www.stcroixgrowers.org), it has a ton more info in it than just soil test guidelines.

11/8/2013 9:47:29 AM

Springfield, Missouri

Thanks Joze, I will have to give that guide a look!

I guess my question was poorly stated. The ideal ratios of cations are "already known" and described as the fundamental principle of base-cation saturation ratios. So for this I will assume we already know the "ideal" ratios of cations with a degree of error that has already been accounted for. For example, in order to achieve a balanced ratio of Ca, Mg, and K one might increase ppm to 6000, 630, and 1200 respectively. When solubility is taken into account this gives a ratio of 12:2:1. In this scenario it is very possible that nothing would grow given the amount of ions in the soil solution...

My question is...

If asked in a poll "At what point should you avoid adding more amendments and just go with a less than "ideal cation ratio"?" How would you respond with the understanding that multiple people and/or cation ratios may be correct given that there are many many growing conditions that we all experience.

Ex. If P exceeds 600ppm...800ppm... so on and so forth?

Again I'm just trying to get a better understanding of everything and I really appreciate all of the feedback.

11/8/2013 11:19:43 AM

Deer Park, WI

your question makes good sense and is certainly one worth asking.

Coincidentally, I was just assigned a paper that discusses Ca/Mg ratios and the implications of shooting for "ideal" base saturation targets. You can find it here:

http://corn.agronomy.wisc.edu/Management/pdfs/a2986.pdf

From I understand, both absolute and ratio values must be considered. The authors conclude that there is no "ideal" Ca/Mg ratio, crop yield is not significantly different at a wide range of values.

However, its important to consider that excessive levels of one nutrient can "out compete" the availability of another, in which case the ratios do have significance.

Those in the "Albrecht" camp of soil fertility philosophy swear by saturation ratios. See Kinsey's "Hands on Agronomy" for a practical explanation of soil fertility management using these principles.

An important point raised in the Ca/Mg article is the measurement of crop uptake vs availability in the soil. Its remarkable to see how little of these nutrients the crop actually takes up relative to how much is available in the root zone.

As you say, 6000lbs/a calcium is like having a tanker of coors light delivered on Packer sunday. you might be able to put away a 12-pack, the rest is just plain overkill.

However, if you have a potassium level that's off the charts, the only way to get that down is by increasing the other cations (Ca, Mg) to balance out their relative levels so that the juice by the root zone is more balanced.

Tough concept with lots of variables and no straightforward answers.

11/8/2013 11:41:16 AM

Lexington, Ky

Location is an equally important factor when considering limiting factors. Kentucky has several seasoned growers that spend the right amount of time in their patches, grow the best genetics using the best practices and the best we can do is a tad over 1,300. Move us up a parallel or two and we might be dangerous....lol.

11/8/2013 12:02:20 PM

Warwood

I also did a 7 yr. study taking existing pumpkins that I could get soil test results for (near 400 pumpkins) and tallied, did stats of actual results which you can compare as pumpkin weight rises. I can send this with the ranges if anyone is interested. also the results were published in the SNEGPG newsletter a few months back. This is a great thread explaining more of the science of K assimilation. these are the studies we need to kee updated on. Things change often, best to keep current.
send requests for the soil results to: [email protected]

11/10/2013 5:09:31 PM