Watering scientifically
Did you know that proper
watering is a lot more complicated than providing your garden with that
critical one inch of water per week? To figure out the best
watering method for your area, first figure out how much water needs to
be lost before vegetables are stressed using the chart below:
Chart 1
| Soil type |
Amount of
water lost before vegetables experience moisture stress (inches of
water per foot of soil) |
| Sandy |
0.5 to 0.75 |
| Medium |
1 |
| Clayey |
1.5 |
Next, pick out your climate zone from this chart:
Chart 2
| Climate zone |
Inches of
soil moisture lost per sunny day in the summer |
| Cool (western Washington) |
0.2 |
| Moderate (northern U.S.) |
0.25 |
| Hot and humid (mid-Atlantic and
southeastern U.S.) |
0.3 |
| Hot and dry (prairies and
northern California) |
0.35 |
| Low desert (southwestern U.S.
and California) |
0.45 |
Then plug your numbers into this formula:
Days
between watering = Chart 1 value ÷ Chart 2 value
For example, in our clayey soil in the hot and humid climate zone:
Days
between watering = 1.5 ÷ 0.3 = 5 days
So, every fifth day, I need to add 1.5 inches of water back to the soil. My father, who lives in the hot and humid zone too but has sandy soil, may need to water every day or two but will add less water each time.
Of course, to maintain a perfect watering schedule, you need to keep track of weather conditions. On cloudy days, the soil doesn't lose much water, so you can wait an extra day to water. When it rains, the amount of precipitation can be added back into the soil's supply, putting off watering even longer.
As further evidence that Steve Solomon and I
are on the same wavelength, Gardening
When It Counts gives
the same irrigation advice I do --- buy high
quality impulse sprinklers and ditch the trendy drip
irrigation.
Solomon notes that drip irrigation equipment is expensive, short-lived,
troublesome, easy to cut
through, and prone to shifting away from the plants it's meant to
water; and doesn't work in sandy soil because the
water won't spread horizontally; but is potentially good for permanent
plantings like
raspberries.For other prime gardening advice --- like why you should never water seedlings --- go read the book!
This post is part of our Gardening When It Counts lunchtime series.
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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.
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Water seedlings in the morning.
Watering? A garden? Are you kidding?
Seriously, After three weeks of drought, my strawberries, mulched with newspapers and some wood chips to hold them down, had moist soil around their roots.
Eliza --- that's what I like most about the book; it isn't afraid to take the unpopular stance. We haven't had much luck with drip irrigation here, but that has a lot to do with our water source (the creek).
Erin --- I'm glad you bit.
I wanted to talk about his ideas on seedling watering, but the post was already way too long and I didn't want to send too many people scurrying for cover. Solomon made the very good point that when you water a plant, you decrease the soil temperature drastically. As Daddy points out in a later comment, watering in the morning (well, late morning) helps with that, but seedlings lose a lot of vigor when the soil temperature drops. Solomon's solution is to use those seed-starting trays --- wet the soil down, put on the lid and let the soil warm back up, then plant your seeds. If you keep the lid on until the seedlings are up and growing, you won't have to water, so the soil temperature will stay high and prevent the formation of fungi that cause damping off.
Daddy --- we've noticed that yields go way up when we water. On the other hand, you use a lot of Solomon's spacing suggestions, which means that your plants have room to range far and wide for water. On the other other hand, Solomon makes the point that the damp soil right under a mulch doesn't mean that there's actually enough water in the soil for your plants to "drink."
Zimmy --- you're totally right about pressure. We didn't really get our sprinklers going until we got a massive pump (free with the thousand gallon tank we got so cheap on Craigslist!) When we were watering on a low pressure system like yours, it was extremely time-consuming and painful. If you have any sediment in your water, it will clog up the holes of your soaker hose and you'll end up with big dry spots and spend a lot of your time running around with a pin cleaning the holes out. Our little yellow stationary sprinklers worked much better in that situation, but you do need a lot of them to water a large area.
HUGELCULTURE INTRO Check out "Hugelculture", or hugelkulture, a German word relating to mound culture.
In brief, at the base of a raised-bed-to-be, put logs and large sticks, or wood chips, or lumber, all of which can be rotting or rotted highly. Why?
To make a catchbasin for nutrients and water. To form a mini-ecosystem under the soil where micro-organisms can have a place to call their own. So that you won't have to water very much at all, and the are will be largely self-supporting for a good many years. This seems better than either Steve's system, and drips, at least for many vegetables, perhaps not greens.
LINKS FOR HUGELCULTURE
This is a simply great thread of discussions on HC. It is based on the system popularized by Sepp Holzer, the man who in the Austrian Alps grows citrus and all manner of amazing things. He has been referred to by at least one man as a “permaculture god.” ☺ http://www.permies.com/permaculture-forums/17_0/permaculture/hugelkultur
TUTORIAL http://gaiacraft.squarespace.com/hugelkultur-lesson/
VIDEOS http://www.youtube.com/watch?v=PnfiWm_O3o4
http://www.youtube.com/watch?v=62ge_AqaVtM