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Monday, January 9, 2012

Gypsum as a soil amendment

Gypsum has been around as a soil amendment since the 18th century.  It comes and goes in popularity.  Right now we are getting a lot of questions about adding gypsum to soils.  Is this a good idea?  As with most things related to soil chemistry, it depends on what is already there.  Gypsum is a good source of sulfur and calcium.  It is NOT a liming material.  Gypsum will not move soil pH at all.

So how do you decide whether or not you can benefit from using gypsum?  What is your soil balance between calcium and magnesium?  If you are high in magnesium, your soil could benefit from additional calcium to improve soil tilth, water infiltration and air movement.  It does this by helping the clays to clump up (floculate).  Water moves more easily through floculated clays.  It is especially useful if your soils are high in clay.

In addition there is mounting evidence that gypsum can reduce soil erosion.  If it improves water infiltration, it is bound to reduce soil erosion. 

Soil sulfur levels seem to drop a bit each year.  Sulfur is one of the essential nutrients for plant growth.  If you are on sandy soils, if your sulfur test is low, or if you are seeing sulfur deficiency, you should be looking to add sulfur.  Gypsom can be a good source of sulfur.

For additional information check out this article in Crops and Soils It is well done.

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