soil experiments?

David R. Hershey dh321 at PGSTUMAIL.PG.CC.MD.US
Wed Aug 21 23:08:46 EST 1996

One demo/lab that always generated a lot of student interest was to buy a 
bunch of small bottles and boxes of houseplant fertilizers and compare 
them based on the cost of a kg of nitrogen. Houseplant fertilizers are 
sort of like patent medicines because of all their catchy names, like 
Granny's Bloomers, Jungle Juice, and Red Thumb (made from blood). Several 
years ago I found a range of $31 to $4663 per kg of nitrogen. At the 
time, ammonium sulfate sold for about $2 per kg. Try to 
get brands to represent all the main types of fertilizers, such as 
slow-release, organic, soluble, liquid, and granular. If you have time, 
you can grow plants using several different brands. You probably won't 
find much difference among brands because houseplant growth is usually 
not limited as much by lack of fertilizer as by other factors, like lack 
of light or water. 

I describe this and several other soil exercises in my book Plant 
Biology Science Projects published by John Wiley. 

Hydroponics is also an easy project that can give results in less than a 
month. The trick is to use houseplant cuttings which root easily, such as 
wandering jew, piggyback plant (Tolmiea), or pothos. Foliar plantlets of 
bryophyllum (Kalanchoe daigremontiana) also work well. You can do standard 
deficiency or toxicity demos or a bunch of other simple experiments like 
measuring solution pH changes. 

David R. Hershey
Snail mail: 6700 Belcrest Road #112, Hyattsville, MD 20782-1340

Adjunct Professor, Biology/Horticulture Department
Prince George's Community College, Largo, MD 20772-2199

Email: dh321 at

On 21 Aug 1996 SCHMID at wrote:

> Does anyone have any ideas for a token lab about soils, fertilizers and 
> such?  I'm looking for immediate gratification sorts of experiments or
> observations, not long-term mineral deficiency studies. (The target 
> audience is undergraduates with an interest in gardening.)
> Kathy Schmid
> schmid at

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