Here comes the rain, and finally! A full .1 inches for the week! (as of this writing) Of course, most traditional garden vegetables require 1 inch per week, but at least it’s something.
So far this year, the unseasonal heat and unusual dry have had us gardeners in S.W. Michigan working over time keeping their plants watered and wilt-free.
And yet, 90% of our garden has received no irrigation this year. We have yet to water any of our established forest garden or hedgerow areas. The small amount of irrigation we have done has mostly come from collected rain water and recycled water.
And that’s because we’ve relied on a full set of stacked redundant tools and Permaculture strategies to create a water-wise garden, starting with an overall site water managememt design.
And while these strategies are fully “research-based,” tested and reliably proven, they are very different from the watering and irrigation strategies promoted by most conventional agriculture/horticulture.
Because, while many of those “flashy” irrigation systems look impressive, in the real world, analysis of industrial-style irrigation systems has often found that results don’t live up to predictions, especially when overall societal costs and impact is taken into consideration. Industrial irrigation depletes aquifers, salts soils, causes soil depletion, and contributes to polluting water ways. Assessments of overall societal Return On Investment (ROI) make it difficult to demonstrate a positive value for irrigation systems. http://www.iwmi.cgiar.org/assessment/files_new/research_projects/CASocioeconomicImpacts_Intizar.pdf
But even without taking into consideration broader societal sustainability, analysis of micro-level ROI for gardeners and farmers has been difficult to positively document, with University studies finding it difficult to recommend industrial irrigation systems. Even highly efficient drip irrigation systems improved profitability by only $7/acre. Sub-surface irrigation, the Rolls Royce of irrigation systems, increased profitability by over $150/acre, but costs, maintenance, and installation were considered to be prohibitive. The costs to anything other than a massive operation simply aren’t worth the fuss! And just wait until one of these systems has a problem, which could easily erase years of profitability.
It is possible to design very specific drip and soaker irrigation for select crop systems, as part of a whole water-wise design, that are useful, cost-effective, and save time, but as the research indicates, it requires some thoughtful analysis and design.
Meanwhile, Permaculture offers a suite of water-wise gardening tools that can are low-cost, easy to implement and maintain, and have a proven ROI. Some of them are arguably free, and actually save time!
These strategies include things like deep mulching, gardening in permanent ground covers, contouring garden beds to catch and store their own water, and managing overall site water resources to get the water to where the plants need it most.
All of these strategies like mulching and bed design are “holistic” and “stack functions.” For example, mulching improves watering, but also fertility, weeding and pest control, so they have compounded benefits, gaining us a higher return, with a lower investment.
According to Cornell, gardens with just a few inches of mulch have been documented to require half the water, 2/3rds less time weeding, and create 8 – 13 degrees cooler soil temperatures. http://www.gardening.cornell.edu/factsheets/mulch/mulchland.html
Which is why Bill Mollison famously quipped: if you take the money you were planning to use on irrigation and put into mulch instead, you’ll get twice as far and be happier for it, too.” Of course, we can even grow our own mulches, making it a free option.
Meanwhile, 4 inches of organic mulch has been found to be as effective as 1 inch of compost for building soil, and building good soil with lots of organic matter is another great water-wise strategy. A 1% increase in soil organic matter can make your watering go further, increasing plant-available moisture between 25 – 44%, turning an inch of rain into 1.44 inches. In one study, this decreased irrigation from 48 seasonal waterings to 36. Each additional percent of organic matter had a similar effect!
And while saving water and time are valuable in themselves, these Permaculture strategies improve produce quality, too. Rather than simply supplying the minimal plant water requirements as drip irrigation does, these strategies regulate soil moisture, which has a significant effect on the quality of a lot of produce, including tomatoes and peppers, which can get blossom-end rot from inconsistent soil moisture, leafy greens which will bolt in hot dry soils, and many root vegetables that can become woody without consistent moisture.