Soil Ammendments - Time to drop Bentonite clay and zeolite?

Hi I am researching what soil amendments are best to prepare for Empire Zoyisa or a soft leaf buffalo.

I have followed a lot of the threads by Fu Manchu (The Garden Whisperer) and it’s good that a process beyond ‘throw the turf down on yellow sand with fertilizer’ is being promoted. I have become confused in some of the specifics though. I see the main thrust of his recommendations have been consistent since about 2009 (please correct me if wrong).

I see that Bentonite, Zeolite, Spongelite are recommended

However I have found conflicting evidence elsewhere that these products are not helpful and the better clay is Kaolin.

Bentonite:

Extra sticky and creates water barriers
Montmorillonite clay (includes Bentonite) content of over 3% in soils has been shown to depress growth

Zeolite, Spongelite

They ‘hang’ onto minerals and don’t release them

Current turf trials at UWA are not showing any real advantage of adding Zeolite to soil, and it seems to be the least effective of the amendments in the trials for increasing water volume or plant available water. Zeolite is commonly used to filter and remove chemicals because they take them in and may not readily release them again, which is not useful for soil as you want the fertilisers to be released to plants. Not all Zeolites are the same. The local WA Zeolite does not add any small particled texture to the soil, and they can interfere with the capillary action of the water flow that fine clays and silts create. Cations and water held by Zeolite and Bentonite are not readily released to plants, and it can take a lot of fertiliser to 'charge' them with that the plants will never get to use.

I found this information here

http://n.b5z.net/i/u/10139343/f/Info_for_landscapers.pdf

http://www.soilsolver.com.au/faq_s

this video which mentions Bentonite and Zeolite/Spongelite

https://www.youtube.com/watch?v=TdsovJfuT9Y

said the super absorbent Zeolite caused the plants to starve 1.09min and the Bentonite (30sec in) particles are bigger than the soil particles and rise to the surface not binding the sand particles and therefore not slowing the movement of moisture and nutrients through the soil.

Now most of that is via one website which some people might say therefore is biased however I note they link to a lot of independent studies.

Also a friend enquired recently with the well known Green Life Soil Co and it appears they no longer use bentonite or zeolite so this development seems a separate confirmation of the above information though their exact reasons for discontinuing were not said. (I mean confirmation only in regards to bentonite and zeolite not necessarily anything else)

Do people here have any opinions or links to scientific fact or personal experience or advice?

Hi Jason.
You are on the right track.
From your links It's clear you have been looking closely into the soil solver range. As a professional involved in the landscape construction industry with a background degree in Environmental Management, I can attest to the effectiveness of Soil Solver.
Gavin Davis, the man behind the Soil Solver range of products,has done his research and has followed the doctrines of soil fertility developed by Neil Kinsey in the US. This links closely with the studies of William Albrecht on the theory of soil balancing which can be described in the following quote from Albrecht:

"One of the basic precepts of soil science is cation exchange capacity (CEC). Clay particles are the smallest and most active constituents of soil. The earth, and clay particles, have positively and negatively charged sites. Positively charged atoms or molecules, called cations, are electrically adsorbed on the clay particles, which are predominately negatively charged. These are then called exchangeable nutrients. Plants excrete H+ which is exchanged for the major cations calcium, magnesium, potassium, sodium and others present in lesser amounts. These cations may be removed by plants, leached to lower soil layers, readsorbed by the soil, or moved into the soil solution and moved, depending on the equilibrium established by the conditions in the soil. Cation exchange capacity (CEC) is the total capacity of the soil to hold exchangeable cations."

While it may sound technical it basically means that you can add a certain ratio of clay to a sandy soil , such as those found on the Swan Coastal plain on which the majority of Perth's suburbs are built,in an attempt to change the soil structure to a loam but if the balance of minerals is wrong the plants can't utilize it to optimum effect.
Bentonite is great for moisture retention but tends to hold on to it along with nutrients rather than giving it to the plants and this is more the case for Zeolite. Great for cat litter, not optimum for gardens.
I have used soil solver in bulk with great success under soft leaf buffalo varieties such as Sir Walter and Saphire.
I have no affiliation with soil solver whatsoever but have met Gavin on several occasions as a customer.
Hope this helps.
Regards
Shaun

hi Lakeside Paving

Thanks for the response. Looking around further and in a way becoming more confused I see the support for

Bentonite
Zeolite
Spongolite

seems to arise via at least some of these links

http://www.plantsman.com.au/page2/files/Plantsman%20Adding%20clay.pdf

http://www.plantsman.com.au/page2/files/Plantsman%20Soil%20Recipe.pdf

http://petercoppin.com/pdfs/amending_improving_gutless_sands_soils_perth_wa.pdf

Further at http://www.petercoppin.com/ I found another link to Zeolite information.

http://www.petercoppin.com/pdfs/zeolite-at-a-glance.pdf

http://www.petercoppin.com/pdfs/zeolite-technical-summary-4.pdf

http://www.petercoppin.com/pdfs/zeolites-abstracts-citations-references-2-web.pdf

This document lists the better of nearly 300 scientific abstracts, research papers, web - based information pages and
information supplied by producers of zeolite in Australia that the author viewed in preparing the report ‘Zeolite –
A Technical Summary’ on behalf of Zeolite WA, which can be viewed on my website or at www.zeolitewa.com.au

So the 'pro Zeolite' side seems to have alot of links as well so to speak.

I have since found this

USING SOIL AMENDMENTS TO
INCREASE TURF WATER USE EFFICIENCY
ON SANDY SOILS: DOES IT WORK

UWA Turf Trials

http://hydrogold.org/jgp/pdf/lib.university_of_wa.soil_amemdments.pdf

I note the study was not on what amendments provide the best nutrients but water use. Interestingly it mentioned that

"Incorporating soil amendments in the top10 cm at a rate of 5-10% (wt/wt) does not necessarily improve turf colour or turf water use efficiency"

"Finer-grained amendments in the topsoil prevent deep drainage but also slow water infiltration and increase the chance of water loss through soil evaporation and growth"

So incorporating these ammendments in the top band seems to be kicking an own goal at least on the water retention front.Though of course it would depend on what exactly the soil composition was prior to the ammendments for a reader to see if it applies to their own locations sand type.

Further into the document it states

"A surface layer of sand of at least 3 cm would allow irrigation water to infiltrate fast thereby reducing initial evaporative losses
associated with slow infiltration. Once in the amendment layer the water would be more tightly bound and less likely to
escape back to the atmosphere, reducing overall evaporative losses"

So it appears one has to get very finicky doing the soil ammendments at least 3cm down and leave standard sand (yellow?) on top. The study unfortunately for the purposes of my interests in creating the thread doesnt really rule at all on the bentonite vs kaolinite debate or the benefits or not of things like Zeolite and Spongelite.

But again what would I know, thats my reading into the document.

Hi

I think i will use Soil Solver Clay Plus and mature compost rotary hoed in 100-200mm. Soil is typical sand near Padbury-Hillary-Craigie

if the area is 200m2, what amount of Clay Plus would you add? according to their site I should go with 10kg per m2 so 2000kg.

and then about 2m3 of Mature Compost say from here http://www.nutrarich.com.au/mature-compost/https://www.homeone.com.au/member/lakeside_paving

How would you prepare it?

You're on the money there Jason.
You want at least 10kg of soil solver. This will delivered as a bulk lot so you will just get a pile of clay .
The mature compost you linked states " We recommend that you spread 5-litres per square metre of Nutrarich Mature Compost before laying turf. " . This comes to 1000L which is eqivalent to 1m3 . It's going to get expensive so you could consider using standard soil conditioner for your humus content which if you are using soil solver is just as effective in my opinion. If you were to use standard soil conditioner you would use 2 m3.
As you have said, you would rotary hoe 100-200mm deep, ideally before retic is in or make sure the retic is deep enough, then level off. Ideally for that you would screed it but if you take your time with a lawn leveler you will get an adequately level area.
Once you've leveled it spread your fertilizer over the top , give it a water and your ready to lay grass.
Shaun

Hi Lakeside (Shaun)

I know Nutrarich has the soil conditioner product and they told me is not far off the mature compost in quality, is this what you mean or do you just mean generically a 'soil conditioner'. I think the soil conditioner is $99pm3 rather then $210pm3 for Mature compost so quite a saving yes.

Also on the very final level see below diagram


If I have set a final level. after rotary hoeing it might end up slightly below the final straight level required. One solution told to me was to use the Soils aint Soils product Special Lawn mix just to get it the last 20-30mm to final level. Or I could use the existing sand I have as I will probably have excess sand.

What do you think of this?

Mate the existing sand will be fine.
Add it then quickly run the rotary hoe back over it or even just give it a rake to the rough level. This will just allow some of the humus and clay to mix through.