Placing the needed potassium directly under the row caused the available potassium level in the soil to increase by too much. In such cases, the first effect is to tie up boron in the soil. Because once potassium exceeds 7.

Then if enough boron is not replaced via foliar applications it can result in smaller potatoes, because boron is needed to transport the starch out of the leaf and move it into the tubers. But even though the lack of boron was affecting the size and weight of the crop, it was not what was causing the temporarily weakened stalk problem and reduced stalk growth for this African grower.

Even though the excessive level of potassium does not tie up the availability of manganese in the soil, it does, along with sodium, block adequate manganese uptake via the soil into the plant. When the potassium and other nutrients were placed below the seed, the potatoes sent their roots right on down to take up needed nutrients.

But the extra potassium applied in that confined area was too much for that soil and once the potato roots entered that area, the blocked uptake of manganese caused weakened stalks and the problem that resulted in sun scald on those stalks.

Potassium is the first key to stalk strength, but manganese is also needed for strong stalks. When the potatoes could not take up enough manganese, all that potassium was no substitute for the needed manganese.

The potato stalks became weak and fell over. Once the roots were sufficiently able to grow out of that excess potassium zone, the plants could again take up enough manganese and the vines straightened up and began to grow as they should.

That was several years ago and since that time, no potassium is recommended under the row on potato land for that company except in the case of new land with extreme K deficiency.

In potassium deficient soils, there will be no problem with weak stalks in potatoes grown there as long as the fertilizer is added in the proper way.

Even though very important to stalk strength in all crops, manganese provides several other benefits for land being used for crop production and when too much potassium is applied, it will contribute to these problems as well. Without manganese plants grow off more slowly.

A lack of it also affects seed set. And for potatoes, in terms of common scab, the worse the manganese deficiency in the soil, the more problem there will be with this disease.

One big problem for growers is knowing what really is enough manganese in the soil for each crop? The answer tends to be confusing because of the various ways to measure and report manganese on soil tests. In fact, the numbers we recommend just to be at adequate levels in the soil will be reported as high to excessive levels on some other soil test reports.

There is yet another problem that growers may have in trying to determine when there is sufficient manganese for the crop. This has to do with using a leaf analysis to determine if plants have sufficient or insufficient manganese.

When the specific soil test we utilize shows manganese as even slightly deficient, common scab can be a problem for potatoes. Yet in too many cases, the leaf analysis shows the level of manganese to be adequate, even when our testing still shows manganese as deficient in the soil.

Which should be believed? The one that solves the problem! Keep in mind that many potato growers use a metallic manganese based foliar to treat for disease.

This can greatly skew the levels shown from the leaf test. But this is not the entire story. Potatoes have been used as an example here due to their extreme sensitivity to manganese deficiency.

And at times, even those who have not used a foliar manganese can have leaf tests that show manganese as too high when in actuality the soils are still too deficient to correctly supply plant needs. However, if your K levels are below optimum, then a strategy to build them up should help your future crops better withstand the next drought.

For more information, contact Jim Isleib , Upper Peninsula crop production educator, at Related MSU Extension News article: Potassium Management by Darryl Warncke.

This article was published by Michigan State University Extension. Potassium fertility impacts hay and pasture performance during drought. Did you find this article useful? Please tell us why? Haul manure? Check out the Michigan Manure Hauler Certification Program!

Learn More. Check out the MSU Dairy Management Program! MSU Product Center helps Michigan food entrepreneurs survive and thrive throughout pandemic Published on August 31, Having a better understanding of how P and K fertilizers interact in the soil and with other inputs will help growers get more out of their fertilizer investment this coming season.

Choosing a P fertilizer that is protected from tie up and a K fertilizer that is highly soluble and free of chlorides will ensure healthier plants to achieve yield goals.

No-Till Farmer's Focusing on Smarter, Sustainable Fertilizing Strategies series is brought to you by AgroLiquid. For over 35 years, AgroLiquid has been on a mission to engineer the best plant nutrition products while safeguarding your crops, the soil and the environment.

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Just one good idea will pay for your subscription hundreds of times over. On this episode of Conservation Ag Update, brought to you by Montag Manufacturing, Amherst, Neb. com Update Profile. By Dylan Rogers posted on January 8, Posted in Nutrient Management , Soil Health.

Phosphorus P Phosphorus is an essential plant nutrient and very important for numerous plant processes and crop production. Potassium K Potassium is also an essential plant nutrient responsible for many vital processes within the plant.

This month's digital sponsors:. KEYWORDS P and K plant interaction phosphorus tie up Potassium solubility. Dylan Rogers AgroLiquid Sales Account Manager. Related Articles [Podcast] Boosting Productivity in Your No-Tilled Soils with a More Efficient, Effective Fertility Program.

Planning Your Wheat Fertility Program: Start Now by Soil Testing. Western Lake Erie Basin Farmers Can Earn Money in New Phosphorus Reduction Program. Report Abusive Comment Thank you for helping us to improve our forums.

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