Hydrophobic soil

[tripsis]

The soil I've been using in my mixes has been from a pile of fill that was delivered to my yard a while back. At the time it looked good, with decent water retention qualities. Over the course of the summer, I've repotted most of my plants, including my cacti and any food and medicine plants which I have in pots. However, once the soil dried out it became apparent that is is actually highly hydrophobic. Once wet it is fine, but if dry it takes a lot of water to moisten it again.

As an example of how bad it is, I was bottom watering some plants (as top watering was proving ineffective) and had the pot fully submerged for about five minutes. After that I took it out, dug down into the soil about a centimetre and the soil below that depth was bone dry.

I was talking to a member here about it the other day and he suggested using a wetting agent, such as one of the commercial surfactants or dish washing detergent. However, after looking into it, I don't like the idea of using these synthetic surfactants on my plants, especially my food plants.

So I've found a few organic solutions which might be effective, but would like to know if anyone has experience using either one. As it has been raining constantly and quite heavily here for the last several days, the soil is thorough wet again, so now would be the ideal time to apply some form of soil wetting agent.

One method I found uses agar as the wetting agent.

You can make your own soil wetting agent using the food grade thickener, agar agar (algin), derived from seaweed.

Slowly add boiling water to agar agar and stir to make a paste about the same consistency as wallpaper paste. Then dilute 250 ml of paste in 4.5 l of water. Water on to seed beds, seedlings, flower beds or containerised plants.

Like any type of wetting agent, algin solution blends most effectively when applied to already moist soil. But unlike chemical wetting agents, algin has no hidden, unexplained or harmful side effects. It’s readily biodegradable, so when transplanted seedlings have established it’s likely to have been digested.

Another solution is a commercial one called Hydretain.

Hydretain attracts and holds moisture in the soil and around the root system so that significantly less water is required to maintain plants during the dryer months.

Used in turf, pot plants, fruit and vegetable seedlings and newly planted trees.

Hydretain is a liquid humectant based soil moisturiser, and unlike water storage granules which are known carcinogens, Hydretain is completely safe and biodegradable.

Hydretain is a revolutionary new chemistry designed to reduce the watering requirements of plants and turf. Its patented blend of liquid humectant and hygroscopic compounds attract free water molecules from the air within the soil matrix and efficiently transfers them into the roots of plants. This simple mechanism results in healthy, vigorous, drought resistant turf, trees, shrubs, ornamental plants and agriculture.

From the same site as the above product is another one called Hydrasoil.

Hydrasoil is a soil wetter for use in home gardens, nurseries and "dry patch" in professional turf situations.

Also used in broadacre furrow applications for cropping in non-wetting sands. Hydrasoil will "harvest" and direct available moisture and rainfall to the root areas.

More info here.

Anyone have experience with any of the above, or can lend opinions on them?

One other question I have is whether any of these would be safe to use on cacti specifically. While I want to soil to hold water, I still want it to be reasonably free-draining.

Edited March 21, 2011 by tripsis

[GoOnThen]

Funny that you bring up this topic now. I had just started writing a rough draft for a thread on using soil wetting agents on cacti. I have been using a wetting agent for the last two years on my cacti and for ten years on the problem areas of my garden.

My father was the one that suggested using it on my cacti as he uses the same potting mix as me just less perlite for his begonias. The problems he was having with rot have reduced significantly since he started useing a wetting agent.

The watering requirements for begonias are much the same as cacti i.e. free draining (they dont like sitting in water)but they like water so the mix must wet all the way through and drain out the bottom of the pots.

Cacti as you know require much the same just a bit less water.

Using a wetting agent does not make your potting mix hold any more water it just wets the mix all the way through so it can supply water and nutrients to the whole root mass. I do believe that there is less water held in a pot that the soil is wet through than a pot that has dry spots in it. This only our opinion but we believe that having dry spots in a pot can cause water to be trapped in pockets of mix and could cause rot.

The other reason to use a wetting agent is as you have found is a lot of soils when they dry out totally they repel water and for a lot of peoples watering cycles i.e. only water when the mix is dry then the plant never gets watered properly because the water never penetrates all the way through the mix.

I hope that my ramblings make some sense

Cheers

Got

Edited March 21, 2011 by GoOnThen

[mac]

Worm castings may be a good option as they tend to have the same effect as soil wetting agents & also give the added nutrients & help with microbes & soil biota

[tripsis]

Thanks for the info guys. Really good to know you've been using soil wetting agents with cacti and that it's been fine, Got. Which one have you been using?

Do you mean solid worm castings mac, or "worm tea"? Other than producing your own, where can you get castings?

Edited March 21, 2011 by tripsis

[mac]

yeah solid casting mixed through the soil, you may have to disturb some of the plants you have already potted

a local nursery or even your local tip may be able to provide you with castings if you dont have a friend with a worm farm

castings from the local tip cold have anything added so a nursery or friend would be the best source

worm tea will help over time but castings hold much more moisture & improve any soil quickly

Edited March 21, 2011 by mac

[tripsis]

Hmmm, I'm trying to avoid repotting them if possible. I have a lot of plants in pots, some of them pretty large, so repotting would be a fair amount of effort. Adding any organic matter to the mix would help, but until they need repotting, I'd like to find some liquid solution to the problem.

I'll look into getting some casting anyway. A top dressing of it would probably be better than nothing. Will get a worm farm happening once i move house too.

[mac]

 

http://www.wormsdownunder.com.au/

 

[GoOnThen]

I have used a number of different brands but the main one I have been using lately is Richgro Ezi-wet liquid.The Ezi-wet seems to work as well as the other brands and it is supposed to be frog, fish and worm safe.

I have used the granules but I don’t think it works as well. With the liquid you can see the difference when you water it in where the granules seem to take time to start working.

I also find using a watering can in the garden you can target the area around each plant or pot as required.

All of my plants in pots normally get two treatments per year and the problem areas in the garden get treated as required

Cheers

Got

[Magicdirt]

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Edited May 8, 2011 by Magicdirt

[planthelper]

worm castings, have an excellent waterholding abielety, but the rule is that,

the better a medium can hold moisture, the more difficult they are when it comes to re wetting.

and indeed, totaly dried out castings are pretty impossible to re wet!

the old fashioned methode is to, put the whole pot into a big bucket with water, for at least 2 day's sometimes it might even take much longer...

often plants spring into life after this treatment with great virgor!! i realy hate hydrophopic soil, because basicly one waste's a lot of water, and the situation often seems to get worse and worse over time.

the growth rate suffers badly with hydrophopic soil. i only use potting mix with a fair ammount of coarse sand, and i think small gravel, helps in the re wetting process.

if you got hundreds of pot's than you would need a very large container to flood your pot's with, but you could try to re wet some pot's in a bucket of water and find out in small scale if it works.

edit: above good post wasn't there yet when i slowly composed my reply.

Edited March 22, 2011 by planthelper

[tripsis]

I suppose mulching is a good idea, as it will help the soil retain water, but not affects its free-draining qualities.

I've been bottom watering the smaller pots PH, but some of them are quite large, up to 52cm, and weigh too much for a single person to lift even when dry. Once wet, I wouldn't be able to get them back out of the container. So I need to find other methods.

[planthelper]

get some black builder's plastic and wrapp it around your giant pots, use sticky tape or rope to keep it up.

fill pot/plastic liner with water, and bob's your uncle.

avoid tearing the plastic, but any big holes can be fixed with sticky tape.

Edited March 22, 2011 by planthelper

[theuserformallyknownasd00d]

I had this problem last summer. I didn't use any wetting agents more looked at my environment/actions for answers. I found that after a full submersion in water for an hour (or until soil is completey saturated) and a good drain, All that was necessary was a good layer of mulch (worm castings then straw). I also made sure they got a good bottom water once a fortnight and a top water in-between when it was needed. This kept everything happy, and still happy to now

Had to change my watering schedule and plans, but I should have used better soil so its the least I can do for my plants.

[tripsis]

I didn't do anything but water more often in the end.

[tipz]

mixing through some vermiculite might help.