Gentle Irrigation
by Ed Fenzel

In 1965, the Israeli Kibbutz Hatzetim opened the first manufacturing facility for drip irrigation components. The scarcity of water in the desert and the desperate need for agricultural sustainability gave birth to the international company we know today as the Netafim Corporation. Netafim is primarily recognized for its unique and proprietary pressure-compensated self-flushing inline drip emitters.

The 1980s were a pivotal time which saw major landscape irrigation manufacturers entering the drip irrigation marketplace, as cyclical drought and public demand for water conservation required alternatives to inefficient conventional irrigation systems. Netafim, Agrifim, Pepco, Rainbird, and Toro were the leaders in developing inline laser emitters, individual emitters to plants, and micro-spray nozzles.

Considerations for a Drip System in your Garden

First, you need to identify the types of plants in your garden and their watering requirements. Next, you need to map out the irrigation zones by plant type and function - tree, shrub, groundcover - then note the category - ornamental, native, edible, or container plant. The technical considerations for a drip system are: I) existing pipe size 2) gallons per minute available (also known as your water volume), 3) p.s.i. (pounds per square inch) also known as your water pressure. Under ideal conditions, a 1-inch mainline with 30 p.s.i. and 10 to 12 gallons per minute as your house water source will meet the needs of most homeowners for a drip system. The next, and certainly not the least important, decision is cost.

What kind of system is right for you?

The best resource for getting information on how to lay out and install a drip system is your Internet browser. Key search words are: drip irrigation, drip tutorial, low volume sprinklers, water conservation, and landscape irrigation. You can easily locate retail and discount outlets by way of Internet inquiry. The main components needed for a complete drip system are:

• Gate valve or ball valve
• Anti-siphon backflow prevention device
• Pressure reducer (optional if water pressure warrants it)
• Filter
• Valves
• Automatic/manual controller
• Mainline tube (3/4-inch or 1/2-inch)
• 1/4-inch lateral tube
• Drip emitters/laser emitter tubing (6-inch to 12-inch spacing)
• Fittings such as elbows and tees
• Freeze-protection king valves

Water Harvesting: Basics for Getting Started

There are several methods for acquiring alternatives to municipal water utilities and well water. For an in-depth view of the process read Brad Lancaster's book Rainwater Harvesting for Drylands, Volume 1. The easiest method of rainwater harvesting is channeling the water that comes off roofs to the canales and diverting it to the plants by installing downspouts and "earth canals" or dry creek beds. Rainwater runoff from driveways, patios, and paths can also be channeled to your plants. If you are at an early enough stage that your hard surfaces have nor yet been constructed then some-and perhaps all-can be constructed of natural pervious (draining) materials such as crusher fines (decomposed granite), compacted sand, gravel, rock, and various walk-on bark mulches, which are all readily available.

The second method of rainwater harvesting is to construct a system where the water is channeled to a cistern either below ground or above ground for use determined by you at a later time. The major considerations for belowground systems are: I) cost 2) filtration and pumping for delivery of the water, and 3) accessibility for maintenance of the system. Above ground systems are less costly to construct and can be used as a gravity feed system, are more accessible for maintenance, and can be more easily installed on an established garden site. A downside to the above-ground system is that it can be unsightly and in most cases requires multiple catchments. In addition, booster pumps and filtration may still be needed.

If a storage system for harvested rainwater is to be linked to an automatic irrigation system, it is advisable to have the entire system designed and installed by a professional. That way, you get a system that works properly for supplemental watering and gives you the reliability and longevity needed to protect your investment. It is generally better to keep your primary irrigation system independent of your rainwater harvesting system, with the latter being a supplemental means of reducing overall water consumption.

When landscape and irrigation are well integrated from the very early stages (including extensive use of native plants), it is entirely possible to use rainwater harvesting only as a means of sustaining your plants.

Reprinted from Taos Green Guide for Sustainable Living, January 2008.

Ed Fenzl is a Landscape Designer and a member of the American Society of landscape architects. He is currently beginning a 1 year term as President of the Los Jardineros Garden Club. He can be reached for inquiries, consulting and design at arseco-150-ski at earthink.net.

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