The palm "terrace" takes shape

The new fern has prompted me to remove the remaining bamboo (a hard task by the way) and start the basis for the palms end of my cretaceous garden. I know "Palm Terrace" is a lofty title but it is a fraction elavated. I plan to leave the center hollow so I can rotate potted palms from indoors. The soil is hopeless clay but in the process of digging out the babmoob runns it has had a good digging over. I plan just to add about 30cm of leaf litter rather than a top soil to gove it a rainforest floor feel. The fern looks quiet happy after its transplant, despite the continued warm (and dry weather)

Waiting for the rain

So the heat (over 40 C) continues, the serious bushfires continue and the weather bureau is forecasting "chance" of rain and "risk" of thunderstorms. I think that is just bureau spin for a few drops of rain, which unfortunately evaporates soon after landing. The drought drags on.

Without doubt the best way to deep water your garden is via natural heavy rain. However the continued dry conditions can cause soils to become hydrophobic (literally it means afraid of the water) which in physical terms it means that the soil gets a skin that repels water. How soils are affected depends on the soil type. In Melbourne the most sandy soils will quite quickly become hydrophobic, the surface affected with waxes from plants, air fall of hydrocarbons and oily polutants and possibly some natural near surface fungal and baterial actions. Melbourne more clay soils (>30% clay) areas will also be affect but only after the clay has started to dry out. First it becomes very hard, and then surface with start get powdery and large shrinkage cracks will open up. This occurs because the clays are loosing their formation water (water that makes up part of clays crystal structure). The fine powder particles of this dehydrated clay are then on the look out for water and will stick to water droplets rather than staying attached to other clay particles. The clay coated droplets soon coagulate and form a mat that forces any further water to run-off.(This drying of clays has the potentially to damage structures, like your house, via subsidence but this will need to be a separate post)

The best way to fix this in the long term is to add lots of organic matter to the soil to change its structure, and add a surface mulch.(when mulches are too thick and allowed to dry out they can apparently themselves become hydrophobic)

In the short term there is a group of materials called Surfactants (or wetting agents). They work by reducing surface tension of water, and are generally complex organic compounds which have one end which is water loving (hydrophilic) and the other water averse(hydrophobic), they work by acting as a joining agent. Soap and detergents are good surfactants, so using soapy grey water on areas that seem to be becoming hydrophobic has some merit as a good way to pre-wet the surface.(but the affect may only last a few hours).

Checking the "soil"

I might have been joking before when I said I didn't know how to water. Where when and how you water depends mainly on your soil. In fact, I often watch Gardening Australia on the ABC and remember a great experiment performed by Jerry Coleby-Williams , where he oven dried three soil types and then monitored how much water they drew from a bucket of water. Read their fact sheet for more information.

So I went and had a look at my soil. Well for starters it isn't soil at all; its just muddy/silty clay with a little organic matter of the top. I figure when I was building up the garden that there was precious little cultivation back in the Cretaceous, so I didn't dig over the garden or add compost to the mud. I do know the soils where often waterlogged back then and problably not like the organic & humic rich profiles we call soil today. But I assume there was plenty of rotting vegitation on the ground, so I just add dead leaves to the surface from time to time. Even with my watering last Tuesday and a few sprinkles of rain since, it is clear my subsoil is powdery dry. The organic matter is however slightly damp. Opps that means I'll be encouraging the plant root to stay near the surface where they are much more likely to dry out. Not what I want at all.

[WATERING MYTH #1:I think a lot of people will discover this the hard way, after "doing the right thing" and mulching their gardens to "drought proof" them, only to find many prize older plants still curl up and die, because their older and deeper roots are not getting any water. All the water is in the satur-aid and mulch at the surface, only the shallow roots will benefit]

Some deeper watering is required, But how?