Iron deficiency in calcerous soils

[sonoranfans]

I was looking at some articles recently about chloroisis and came across 7-8 peer reviewed AG articles.  We have recently been having discussions here on deficiencies so I though this might be useful to drop some in formation here.  The research reviews tend to be specific experiments so they might be less clear than this AZ agricutural extension article.  Specifically it discusses Fe deficiency in calcerous(high calcium) soils.  One interesting behavior is that over watering causes Fe deficiency in calcerous soils.   Calcerous soils tend to occur in areas with low rainfall out west and also limestone.  Clays are often calcerous as well since Gypsum is CaS04 and is a common component of clay.  The article mentions soil pH as well, certainly it can knock iron out of solution.  https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1415.pdf    The treatment of calcerous soils with sulfur/Iron sulfate is also discussed.  If you do have high calcium coil, your palms will be more susceptible to iron deficiencies from overwatering.  

[sonoranfans]

another article from colorado state:  https://cmg.extension.colostate.edu/Gardennotes/223.pdf

 

[Swolte]

I was just reading up on this matter as I was told to use sulfur additives. The more I read, however, the more I become convinced they may not be a very good solution. Here's another article I found that adds to that chorus: https://www.agvise.com/adjusting-high-soil-ph-with-elemental-sulfur/

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[teddytn]

It’s definitely not practical to amend an entire back yard let’s say, but over time applying organic compost and getting the soil activity up, will usually prevent or fix most of these problems. Companion planting, introducing mycorrhizae fungi to the roots of plants creates a symbiotic relationship. The plant signals the mycelium that it needs a nutrient or mineral, the mycelium gathers it for the plant and the plant in return gives the mycelium sugars. Try to create the forest floor and the “magic” starts, create a habitat that Mother Nature approves of and she shows up. Same applies  under the soil surface.

[amh]

The best long term solution is having a healthy microbial community, successively adding compost, using ammonium sulfate fertilizers, and sulfur will help acidify existing soils. Using iron sulfate as a foliar spray will help specific plants. These actions will not allow you to grow blueberries in alkaline soils, but they will help with less sensitive plants.

[Dartolution]

Very good articles! Thanks @sonoranfans

[sonoranfans]

Yes sulfur cannot work on high limestone soils as stated in the articles I posted.  The 100lb/acre elemental Sulfur amount in Swoltes "Agvise" article is way less than I used since I was only locally adjusting pH near the root zones of my sensitive palms.  I used about 30-60 lb a year(2 bags) for about 1000-1500sf, about 0.02 acre which is about 10x more what they tested pH at in lb/acre and it worked quite well on Mn deficiency as well.  And yes its not a one time thing, but it did work on my alkaline clay in AZ, applied 30-60 lb a year which cost like $25 (?) year so it is quite practical.  Under application of sulfur gets you mimimal change.  In places where you have lots of CaCO3 in your soil like miami limestone rocky soils, its best to just stick to pH adapted plants.  The Agvise article is good for farmers, not so much for hobbyists.   Farmers are all about how it impacts food cost and hobbyists buy palms that are decorative.  You just have to look at who the articles are written for, AGvise is a commercial AG entity so they are less focused on us non farmers.  Commercial farming is about optimizing/minimizing costs for production.  

[sonoranfans]

Good also to remember that Ferrous sulfate has a pH of about 2, so you can way ovrdo acidity with it.  CaSO4 which is what you get when adding sulfur to high calcium soil has a near neutral pH so the real risk of pH burn is not with elemental sulfur but with Ferrous sulfate.  This is why I dont recommend the use of an instant pH adjustment like Ferrous sulfate, thre is a high burn risk.