>It's my understanding that high water needs plants like about an inch of water per week.? 400 sq. ft. would be about 33 cubic feet.? With about 7.5 gallons of water in a cubic foot, you'd need about 250 gallons per week, or about 1000+ gallons per month.? I tried looking up average monthly rainfalls in Boulder, and they're all over the map!, but it seems to be expected between 1" to 1.5" per month in the spring and summer months.? So, you'd need to supplement the rainfall by about 600-750 gallons per month.? A four month season might need in the area of 2500+ gallons.?
>Of course, using those good water practices? -- like the mulch and the roof cachement and the planting patterns and the hardier plants -- would probably cut needs down "quite a bit".?? ********************************************************** Water needed at 1 inch per week if paths are not watered ********************************************************** And if the gardens are individually fenced on all four sides or not fenced and touch other gardens on 3 sides, people using wide beds will probably do a pattern of the following to get the most growing space: 2 foot wide bed 1 foot path 4 foot wide bed 1 foot path 4 foot wide bed 1 foot path 4 foot wide bed 1 foot path 2 foot wide bed With a 1x17 foot path up the center (or a side) (-3 feet already in other paths)for access With hand or drip watering, the paths wouldn't need to be watered, so that's Four 1x20 paths = 80 square feet One 1x17 path - 3 feet already in other paths = 14 square feet Total of 94 square feet in paths So that would mean 306 square feet to water ~25 cubic feet of water per week ~7.5 gallons of water in a cubic foot ~187 gallons of water per week My guess is that in most years the water table will be high enough from the melting snow of April and the 3+ usual inches of May rain that the garden wouldn't need to be watered in May. (People would need some water for their planting flats at home though.) For the 9 weeks of June and July, there would be a need for 9 inches of rain, but on average there would be only 4 though some years would have 6-7. So with 4 inches of rain, 935 gallons would be needed. For the 9 weeks of August and September, there would be a need for 9 inches of rain, but on average there would be only 3 though some years would have 5. So with 3 inches of rain 1122 gallons would be needed For those four months, that would be 2057 gallons. ************************************************************************* Collecting water in 5 gallon buckets from October to April on 1 plot ************************************************************************* The average 5 gallon food grade bucket is about 1 foot wide at the top and about 10 inches wide on the inside bottom. So from October to April, you could put 94 buckets on the paths to catch the winter rain and snow. On average about 10 inches of water would fall. So each bucket could collect about Pi x r2 x h = pi x 25/144ft2 x 10/12ft = pi x .1736 ft2 x .83ft = .45ft3 Or 3.375 gallons of water each. 94 buckets could collect ~317 gallons of water This could be transferred to 64 buckets for storage. Stacked three buckets high they could go in a corner space about 4x5 feet. They could also be placed between tomatoes and peppers (but not stacked) as a temperature moderator in the early summer. The water in the buckets could be used up in June as needed. (The 30 now empty buckets could be used to collect the 3+ inches of May rain if desired. But try to locate them where you won't need to walk often as it's time consuming to keep shifting out of the way for access to the beds. It would give about 31 more gallons of water though. Combine and cover filled buckets after rains if it's getting warm enough for mosquitoes.) 2057 gallons needed - 317 gallons provided by winter precipitation would mean that 1740 gallons would be needed from the piped in water supply. Restaurants and bakeries get a lot of supplies in 5 gallon food grade buckets. Ask them to save you the lids, so you can prevent evaporation once they are filled and so you can stack them. To lessen the chance of them being blown down when stacked, tie the third row to the fence on the exposed sides of the stack. ************************************************************************* Estimating reduced needs if more drought hardy plants are used, plants are mulched, etc. Additional strategies. ************************************************************************* This is hard to figure out. You may want to have a test garden or two and try several types of plants with several different watering schedules and amounts. Or some of the extension or university test gardens may already have data you can use to figure this out. Group plants by watering needs such as tomatoes, peppers, and greens in the higher water zone and sage and rosemary in the lower water area. That way more of the water can go to the plants that need it. One factor in tomatoes though is that irregular watering can increase blossom end rot and cracking. Save the water used from rinsing shovels or root vegetables to water a plant. Watering once a week will help the roots go deeper. In most years the roots of spring planted vegetables may be able to grow down as the water table drops and not need much if any supplemental watering. Some plants have most of their roots near the surface though, so they would need to be watered each week if it doesn't rain. Check that the mulch has lots of spaces for water penetration. If it forms a crust, the water will just run off when it does rain. Put drip irrigation under the mulch to reduce evaporation Create a basin around plants such as peppers or tomatoes to direct water to the plant roots and prevent runoff. You may want to have a contest, or just a friendly informal informational competition to see who can grow a diverse abundant garden with the least amount of piped in water. After a couple years of experimenting and soil improvement you might see that the gardeners can grow 1216 pounds of vegetables with intensive growing methods using half their beds twice for cool crops and half their beds once for warm crops with their 1740 gallons of piped water plus average rain. Or sample test gardens might be a good experiment for university students that need a project. Sharon [EMAIL PROTECTED] _______________________________________________ The American Community Gardening Association listserve is only one of ACGA's services to community gardeners. 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