The margins are doubtless so narrow that it's not feasible, but pumping during the day into a storage tank, and irrigating at night (while evaporation is relatively low) would be a way to slightly improve soil (though not aquifer) recharge.
Certainly it would require less water volume, but again, the infrastructure costs for panels + submersible + storage are probably untenable in precisely the places this is needed most (and where the impacts of depleting the water table will hit the most).
Yes, sub-surface, or drip close to root zone, is perfect -- however that's really expensive, in terms of capex as well as maintenance, harvesting, etc.
Drip systems tend to require a) a lot of pressure, and b) a very consistent pressure, to get reliable output. These are also expensive to buy & run.
Drip or leaky-hose type underground systems are difficult to maintain (I've tried!) just because you can't see them. The way you find out something's wrong is usually because a plant or an area is looking very very happy, and other plants / areas are dying off.
Under-mulch is good, but doesn't lend itself to broadscale cropping as described in TFA.
Drip is used quite a bit in Northern California for higher value crops like tomatoes, but it's too expensive for normal crops. It also seems like a non-starter for smaller scale and poorer farmers in developing nations; that's a lot of CapEx for generally lower value crops.
It means that method of farming is a bad fit for that climate, yes.
Its a much more complex problem though. Most farms in the US depend on debt and subsidies to get by. That money comes with strings attached, from the yield required to cover expenses to subsidies that require mono-cropped fields that basically sit idle in the off season or when a crop fails.
There are different techniques that could be used, but none of them will match the sheer tonnage of yield from a mono-crop drenched in fertilizer, herbicides, and laid out in a way that allows for massive tractors and combines to be used. All of these methods cause huge damage to the land, but again I'd argue we've left those farmers with little to no choice in the matter given how our food system is designed.
Fair. I just edited my comment because I combined two concepts and muddled them together. It's more common to suffer a poorer yield than total crop loss. But crops like tomatoes can die from lack of water during high heat days if the heat lasts for several days. Also, irrigating only at night (not just evening, but over night) can contribute to fungal and disease issues with some crops.
Sure, cucurbits and solanaceous crops and prone to humidity / water induced fungal attacks. Tomatoes are better watered at ground level (refer other thread about drippers) or even just flood irrigation.
Tomatoes are actually pretty robust, if you grow them properly.
The way I was taught to maximise survival / yield in hot climates is to grow as seedlings for a few weeks, until they're maybe 30cm or so tall. Dig holes ~ 25cm deep, flood / drain / flood / drain - and then take all but the upper few branches off the seedling, and plant, backfill with soil, so about 5m is above-ground.
Because they have adventitious rooting you've effectively just given them a massive reservoir of water retention. This is obviously expensive at scale (though not intrinsically infeasible) but works superbly well in hostile, arid climates.
I expect the next decade or two will force a lot of changes to the way food is grow in already marginal climates.
If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.
> If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.
Sure, but almost all the countries TFA mentions are generally farmed by small landholders, so irrigation via stored water is not infeasible. The mammoth style broadacre tiny-return-per-hectare, heavily mechanised, fertiliser- and insecticide- reliant style agriculture popular in the USA isn't so common in these places.
The 'dent in the aquifer' you mention (and TFA dwells upon) is because there's thousands of people doing the same thing at the same time to the same aquifer for years on end.
Regrettably TFA doesn't talk volumes, other than three mentions of 'cubic miles'.
Apart from an exasperated 'why do they use anything but metric?' sigh, it's also obviously a heavily aggregated figure across large geo regions.
These small holdings with their panels + pump per field, pulling from an increasingly deep water table, are presumably extracting probably in the range of 10-20 kilolitres of water per day - the size of an average plastic water tank that has a one-off cost about the same as a submersible DC pump + panels. (Lined steel, concrete, etc, become more attractively priced at larger volumes.)
So, yes, absolutely, if your geography allows, then put in a megalitre+ sized hole in the ground up-hill, cover it to reduce evaporation & algae, fence it to prevent animal damage, etc. Happy days.
Certainly it would require less water volume, but again, the infrastructure costs for panels + submersible + storage are probably untenable in precisely the places this is needed most (and where the impacts of depleting the water table will hit the most).