Re: Soil comparisons & Dissolving K2SO4

Dr. dave writes...
>If you want published scientific information go to,
>	Smart, R. M. and Barko, J. W. 1985. Laboratory culture of 
>submersed freshwater macrophytes on natural sediments. Aquatic Botany 21; 
>251 to 263.
>	Barko, J. W. and Smart, R. M. 1986. Sediment-related mechanisms 
>of growth limitation in submersed macrophytes. Ecology 67; 1328 to 1340.

How about some unpublished heresay? When you or Paul K. use soil as
your substrate, what sort of pH are we looking at? Do you ever employ
limestone based topsoil? Did you mention organic content in the range
of 10 % to 20%? What are the consequences of placing topsoil in the
tank without the five week composting?

>As I mentioned recently, laterite is by definition a highly weathered red 
>clay which contains primarily iron and aluminum. However, having no first 
>hand experience with laterite (textbooks and lectures only) I cant really 
>say for certain that this is ALL that it contains ... I'm sure K. Schoeler 
>can fill you in with more detail.

Doesn't Karl add chemicals to his laterite?

Paul Rothel writes...
>However the potassium
>sulphate was a granular form which looked almost like small
>gravel about 1/8 in in size.  When I tried to mix it with 
>the water it did not want to dissolve.  I stirred it and 
>shook it up repeatedly, then I left it set overnight and it
>still has dissolved very little.  Is this the right stuff
>and if so How do you get it to dissolve?

It helps if the water is warm.

Dave Whittaker                       ac554 at FreeNet_Carleton.CA
Gloucester, Ontario                  dwhitt at magmacom_com