In alot of Australia you will NEED to use top down watering. The idea here being that POOR farming practices, conservation and stewardship have created conditions of toxic salt buildup throughout the country. Doesn’t matter if you’re saving water when the methodology that you are “saving” water through is contributing to the problem. I recommend Geoff Lawton for learning about these things; he’s a world reknowned Australian permaculturalist. The secret to detoxifying and remediating the Australian landscape is mycology.
This is wrong. http://www.mdba.gov.au/managing-water/salinity what has triggered a lot of the Murray Darling basin problems is in fact top down watering where water is pumped out of river than watered. Result of over watering by topdown is water going into the high saltly water table and bring it up.
One of the researchers of the Australian Wicking gardening system is none other than Geoff Lawton you have just attempted to throw in my face. Also you have to watch what he found in his first project at the start of that video you quoted.
Yes he found something very interesting if you don’t over water get conditions exactly right salt ends up bound up in inert forms to plants inside fungi and the like. His early overseas Swale work is the base to system shows something super important.
In fact you are horribly wrong. Lot of Australia need to avoid top down water or any method that can over water like the plague. When some of the under ground water is just as salty as the dead sea you really do not want to raise that under under any condition. There is a reason why Geoff Lawton need to work over in some of these other countries instead of taking on Australia salt problem. The overseas problems are in fact simpler so he could experiment with watering above levels that can be performed safely in Australia due to those areas not having high salt water tables.
Australia has run dry land farming for a very long time next to top down irrigated farming. The horrible fact here is dry land farming does not suffer from salinity why that was the case was explained by that overseas work by Geoff Lawton with what he found in that video. Yet the top down irrigated farming has been suffering from the issue in Australia.
Yes it right that poor farming practices lead to salt build up. Also mycology does not like getting over wet. This is why a lot of work is going into wicking tech is to use as min possible water. Mycology to manage salt on average to manage salt require a fairly large area for a large area fungi. So a lot of farming practices have been kill in soil friendly fungi.
The reality is Australian government intentionally makes water expensive for farmers to force usage of more and more effective water application. To make irrigated farming as close to dry land farming as possible. Basically nature knew how to apply water and we have been idiots applying to much and moving water tables the wrong ways. Add in being idiots killing the mycology parts for salt control. Add in being idiots destroying the complete soil structure… You can get away with a few idiot mistakes and nature forgives you but do them all and nature takes a revenge.
Now the fact you need in soil fungi to control salt and fungi on leaves are bad for plants its critical that water is applied avoiding leaves. Also you need to watch that video carefully watering is done by dippers or swale what are both water without hitting leaves. Swales in Fraser island tells us the organic matter in the bottom of them to regulate the water outflow speed into the soil. So just digging a Swale without organic matter does not work right.
Sorry the need to use top down watering by man made ways is very limited. Top down watering is mostly want and cost avoidance.