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Effect of a Montmorillonite Clay on the Productivity of Spinach

 (Spincia oleracea)
 

By: Kirk E. Waterstripe, Assistant Professor
Jared Milarch, Undergraduate
Northwestern Michigan College, Traverse City, MI

Synopsis of Developmental Research

Montmorillonite clay contains a combination of 67 trace minerals. It has been shown that, although trace elements are necessary for optimum plant growth, they can be harmful or toxic at high levels. On February 18, 1998, spinach of the Long Standing Bloomsdale variety were seeded identically in flats containing either none or incremental levels of montmorillonite clay. The purpose was to determine if there is a growth benefit with montmorillonite clay supplementation and if so, the optimum supplementation level. Treatments were: 1. topsoil with 14% composted cow manure (TC), 2. TC plus montmorillonite clay at a rate of 1lb./10 sq. ft. (TC1M). 3. TC plus montmorillonite clay at a rate of 1.5 lb./10 sq. ft. (TC1.5M). 4. TC plus montmorillonite clay at a rate of 2 lb./10 sq. ft. (TC2M). All plants received similar light, temperature, and moisture.

Results:
Thirty-nine days after planting all plants were separated from the soil and rinsed clean. Green mass growth is shown in Figure 1. The highest level of montmorillonite clay addition (TC2M) produced the greatest green mass of 4.25 grams. The intermediate (TC1.5M) and low montmorillonite clay level (TC1M) produced respectively 2.87 and 2.63 grams of green mass growth. The control treatment (TC) had the lowest green mass growth of 1.93 grams.

Conclusions:
The addition of montmorillonite clay benefited spinach growth compared to the control treatment (TC) of only topsoil and 14% composted cow manure. Increased spinach green mass with incrementally higher levels up to 2 lbs/10 sq. ft. of montmorillonite clay demonstrates the optimum level of montmorillonite clay supplementation likely exceeds this rate. Further research must be conducted to determine the optimum and potential toxic levels of montmorillonite clay supplementation as it affects spinach green mass growth.

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