Water is a scarce and precious commodity here in the high desert of Colorado. The State water laws are labyrinthine, the cause of bitter wrangling and pitched battles over the last century. Luckily I have my own well, plunging 600 feet deep through the granite, tapping an underground stream fed from snow melt which may be as much as 50 years old. Even as the weather gets more chaotic with global warming, I know there is plenty of water down there.
Even so, I am miserly with every drop of this life-giving essence. As human activity uses up increasing portions of the worlds limited resources of fresh clean water, we gardeners and growers have to become ever more careful and conserving. We need to be wise in the ways of water.
Water is dynamic and has an incredible capacity to bring life and carry energy and nutrients. Plants breathe in moisture from soil and air. A portion is exhaled through leaves in transpiration. Plants are both conduits and consumers of water; it creates their bodies, transports minerals and makes up over 95% of their structure. Water is obviously the life-blood of the vegetable world – but it is much more.
Water and the Soil
Whenever we irrigate our gardens, we are not simply feeding moisture to plants. Plants are rooted in a living system that includes minerals, humus, soil life, air and water. As water penetrates the soil, it displaces the carbon dioxide that has accumulated from the break down of organic matter. Draining water draws in oxygen, nourishing the aerobic microbial life. Watering is as much about soil oxygen replenishment as it is about moisture. The overall aim is to maintain a balance of about 25% water and 25% air in the soil.
Dampened soil grows dark as sponge-like humus soaks in moisture, storing it for later use and activating the microbial life in its pores. Bacterial and fungal spores germinate, reproduce and migrate. Protozoa colonize the watery spaces between mineral particles. Worms move towards the surface and plump up as they ingest moist soil. Water brings the soil alive.
I remember my initial surprise when my brother John told me years ago: “Always water every inch of your soil, particularly if it is bare and unplanted.” He explained that dehydrated soil stresses and kills billions of living organisms. It is our job to keep them all moist and happy — then they will work for us building stronger healthier plants. The rule of thumb in irrigation is, soil first — plants later. Dehydrated plants signal their need for water by drooping. Soil tells us it needs to drink when the surface cracks or half inch below the surface is dry and dusty. Listen to the soil as well as the plants.
When you irrigate your garden, you need to know the quality of your water. Of course, rain is best. We all have seen the magic a warm drizzle can work on a dried up landscape; plants seem to perk up and vibrate with aliveness. Oddly enough, scientists cannot seem to agree on the cause. The consensus is that rainwater dissolves the gases of the air as it descends: oxygen, carbon dioxide and nitrogen. It also may pick up a particular ionic charge. As spherical raindrops hit the ground, energy and nutrients (possibly nitrates) are released giving soil and plant life an immediate boost. Stored rainwater is also beneficial but loses some of its qualities over time.
While we have little rain in Colorado, I am lucky to have my well. My water is free of pollution and has no anti-bacterial additives. Those dependent on municipal water supplies may not be so fortunate. Consumer advocates suggest there are over a thousand possible contaminants in ordinary drinking water. Do some research and find out what your water contains.
Most city supplies have added chlorine that kills bacteria. While chlorine easily dissipates into the air, the more recent additive, chloramine, is more problematic for gardeners. Soil life and young plants are vulnerable to this very stable anti-bacterial. If you know your water has chloramine, you may want to use an activated charcoal filter or treat your water with hydrogen peroxide or possibly vitamin C before watering. Again, research the best methods of purifying your water supply. As an aside, microwaved water is not good for plants.
Pure water is particularly important when making compost tea. Anti-bacterials in your water can decimate the microbial life in your tea starter – whether worm castings, compost or specialized humus. If your water has chlorine, let it stand for 24 hours or bubble air through it for 2 hours. Treat chloramine water in a way that leaves the water close to a neutral pH of 7. Usually, once the compost tea is brewed and the microbial life is strong, diluting the tea as you apply it does not overly harm the microbes.
All gardeners have their own preferred irrigation methods. Simple hand watering is often the most efficient but it is time consuming. Automatic sprinkler systems are common and probably the most wasteful. However, innovative systems such as the SpritzWiz (www.spritzwiz.com) create a powerful intermittent stream that uses half the water. This has far better results for the soil as it allows time for water and air to penetrate.
Rubber soaker hoses made of recycles tires are relatively cheap and available, but can clog in hard water areas and last only a few years. They are a good standby for row vegetable gardens. More sophisticated high-pressure drip irrigation systems are efficient and extremely flexible, particularly when watering containers, individual trees, shrubs and perennials. The parts tend to be expensive and complicated. There are dozens of different fittings available and it is often difficult to know which ones to use.
My own preference, after many trials, is a drip irrigation system called T-tape. While not readily available in stores, it is extremely efficient and is used by a majority of horticulturalists. The T-Tape system uses low-pressure water and is suitable for flat row or raised-bed gardens. When set up with a filter, the emitters seldom clog and the tape lasts for years. It is best ordered on the web from suppliers such as Fedco (www.fedcoseeds.com) or Drip Works (www.dripworks.com).
In my drive to use water efficiently, I installed a gray-water system that supplies all of my greenhouses. A large tank is replenished by water diverted from baths, showers and the washing machine. From there, it is filtered and fed at low pressure to the T-tape.
In a gray-water system it is essential to use organic soaps and stock your soil with microbes (using compost tea) that can break down residues into plant-available nutrients. Then you do not get any smells and the soil remains sweet and fertile. Never use water from toilets or the kitchen sink — that is unusable black-water.
What little rain we get is also collected from a roof and sent to the holding tank. A 1,000 sq ft roof can capture as much as 650 gallons of water during a 1-inch hard rain. If you live in an area with any rain, store and use as much as you can. Some states such as Colorado have arcane water regulations, so check them out first.
Once the water is in the soil, you want to keep it there. Always minimize the impact of direct sunlight and heat on bare soil. Close planting, shading and mulching substantially reduces evaporation, keeps roots cooler and protects soil microbes from deadly ultraviolet rays. In the heat of summer, shade cloth can be a blessing for cool weather crops. Use floating row covers for delicate seeds and for emergency shading.
Mulching is the most effective way of trapping soil moisture. Organic mulches – compost, leaves, grass clippings, straw, hay, alfalfa, etc. – not only keep soil moist but also promote soil life. Other mulches – plastic, treated paper, bark, rock – are often more convenient but may harm the soil over the long term. For added benefit, lay drip irrigation beneath the mulch so that the moisture seeps downward and none is lost to evaporation. Water is a taken-for-granted miracle — the sustainer of life. We need to be grateful for and considerate of this amazing yet limited resource. With a few simple changes to the way we think about and use water, we can make sure our plants and soil have all the life-giving moisture they need.
Learn to Water Well