Irrigation in warm climates

Hello,

I am looking for some advice about irrigation in warm climates.

I've been working on a project in Northern Portugal (www.flirtingwithyurting.com) since January. We have already started growing quite a lot of fruit and veg and, considering what we started with, it hasn't been too bad. The main problem we are facing is how to most efficiently water the annual veg. The fruit trees and perennials seem to establish very quickly and are quite happy being left to it with a big pile of mulch around them. We have found however that the annuals are much more thirsty (probably because of smaller/less developed root system).

We mulched all the annual beds with newspaper and then shredded bracken/leaves or whatever else we could rake up. In the UK, I've found this method to be sufficient enough to stop watering all together with most crops, once they are settled in. But Portugal is obviously much hotter, and receives less rain in the summer. Furthermore, the soil here is very sandy so it doesn't hold on to moisture for long. We are having to water the annuals quite frequently, but the mulch prevents the moisture getting into the soil, so we are throwing much more water onto it than if we had no mulch. It is currently quite inefficient. The locals use flood irrigation. They make gullies between the rows of veg and flood the whole veg bed once or twice a week (water is not in short supply here as nearly everyone has a water mine/spring). This seems like a great idea were it not for the massive soil erosion and over time it increases salt in the soil. We have also considered leaky pipe, but I've used them before and I HATE them. They cost money, they restrict access to the soil, generally get in the way and end up in a mess.

So.... Has anyone got any tips on how we can keep are annual veg well watered?

Thanks very much

Luke

Newspaper isn't the best mulch for Portugal - it tends to form a semi-waterproof barrier! Pine needles or bark chippings are good as they let water flow through easily but don't let it evaporate out again. Some form of drip irrigation works well, if you like that sort of thing. Place it *under* the mulch so nothing evaporates. I like to dumpster-dive for used 5 litre water bottles then cut the top off, punch a hole in the bottom, stand them next to any plant that needs a bit of extra water and fill with water as necessary. The water drips through slowly enough that it has time to be absorbed into the soil right where it is needed.

I'm also experimenting with hugelkulture - click on the word and it will take you to an article. It's basically a raised bed build over a heap of wood which acts as a giant water-holding crystal. In Tamera they use really tall ones but I don't have that much spare soil so I'm experimenting with digging out a pit, filling it with whatever wood I can find, then using the soil I've dug out with whatever compost I can find to cover it with. Then mulch on top. The wood will absorb water when it rains and release it gradually during dry weather. In most climates irrigation is never needed on them, but so far everyone I've spoken to in Portugal who has used them has said that they do have to irrigate a bit, but far less than normal.

i agree with Burra about paper as mulch, if you do have to use the paper, mix it with more than equal amounts of other materials to keep it from packing, oh and shred it fine before mixing it so it mixes well..actually i think it is better if you can mix it to less than a 4:1 ratio, then it isn't going to clump as much

Thanks guys. I should clarify that the paper is layed out in sheets, like you would when sheet mulching, to act as a weed barrier (which it does quite effectively!). But yes, it does seem to be the main issue with preventing the water getting to the soil. Drip irrigation is out of the question for me. It drives me nuts! I've experimented with the big 5l bottles etc, but I dont want them everywhere.

We have a friend over here who is experimenting with hugelkultur. I haven't read much about it yet, but will look into it. thanks for the link.

Burying wood is where it's at. It will trap moisture down deep, and tempt the roots down to it, and act as a fungal haven too.

They did a study out in the worst part of the Mohave desert out in the west, and found that mulches did exactly that, sucked up the water, while not allowing it to perc down to plant roots.

best mulch for desert is..... rocks !

a couple layers of flattish rocks (especially if you can get lichen growing on them) will allow water thru, and seal it in.


If you want to try the low tech method of drip, look for the drywall screw trick. drill a drywall screw straight thru both walls of drip line. now back it out on the tip side, till you get just the flow you need at the furthest reaches. if it plugs, just back it out for a second, then screw it back in to get the flow you want.

I'm now thinking of abandoning the newspaper sheet mulch and using wood chip/bark as mulch, which can be dug into the soil every time we replant the annuals. I didn't realize how good wood was at holding onto water but lots have people have been suggesting burying it on other forums too.

I posted about Pitcher Irrigation. It might be something for you to consider.