Hi sean,

Some info is missing but by the way you have described the question you have an inkling or know a little of the answer to the question you ask. Please explain what plants that each drip type irrigates and describe the configuration that is used (straight line,looped,curved,etc). Was this system installed by a landscape contractor? In fact take a stab at an answer and the forum will comment on it and add other information. Aloha.

Thanks lehual - Last question first. All of the systems were installed by a contractor who has now relocated. The valves are controlled by a system that receives electronically provided information about the weather and irrigates accordingly. The native soil was enriched with what was called an 80/20 mix and crushed rock was also used to improve drainage The black lines from what I can observe are straight and from what I can remember the brown lines were laid in several loops. I believe that most of the black lines water shrubs like phormium, dracena and other low water usage plants. I also believe that the brown lines are used to water the trees like eucalyptus, acacia, australian willow, again low water usage plants. We have no turf or other groundcover. Mulch is used however on the unpaved portions of the soil. The contractor also installed a number of drainage lines and two cisterns, one for slow ground water recharging and another with a pump so that the gray water can be reused. There is no appreciable run-off on sidwalks or the street. Unfortunately my spouse and I were at work and the kids where at school when most of the construction was taking place last year and so we didn't get to observe much until after the systems were installed. BTW although we are operating under water usage restrictions in our region, we did leave some room for several of your natives and our favorite plants, the plumeria. I would like to know the reasons for using the brown vs. black lines other than the obvious that the former irrigates trees and the latter waters shrubs. Are one type more expensive, or more effective than the other? We are planning on expanding our landscape and the new contractor seems unfamiliar with these issues. Thanks.

Sean,

Thanks for continuing the discussion. From your answer, it seems that me your previous contractor knew what was what. I am familiar with SoCal soils which are very clayey including underlain with caliche and the crushed rock is good for this soil. How deep was the amendments applied? I am not familiar with the 80/20 mix? Is that Organic/Inorganic ration or Nitrogen/phosphorus. I assume they did a soils test before they applied the amendments anyway. Drip irrigation is the most efficient irrigation method (90%) but like anything else that assumes perfect application rate and timing for the soil type. The brown and black hoses are drip systems. Soaker hoses are not as efficient and tend to over apply water because their rate is not uniform over their length. To help your drip lines with uniform flow, they should be place with a slight down slope. This is not crucial with level ground but not with a moderate up slope. The point of drip is to apply water where the plant can use it and not anywhere else. That is the root zone. Different plants have different root patterns. Some have shallow roots that are dense near the surface so weeding can damage roots and mulch is very a effective way to protect the roots and minimize weeds. Other plants especially trees have deeper roots that search farther from the plant usually to the edge of the tree's canopy drip line. Drip's water plume shape is pear shaped downward. The plume's ability to move out sidewards is dependent upon the fine particle make up of the soil. So clay soils do better than sandy soils. The surface lines are for the shallow rooted plants and the brown should be more for the trees, but they can be used for both. Larger plants and trees should have loops of varying sizes until they are well established and probably do not need to be irrigated anymore. The lines below the ground are to get to the deeper roots and are not susceptible to animals searching for water. All drip tube is susceptible to clogging. The non-visible lines are harder to detect that they are not working. Again frequent probing is what a gardener does. If you want a totally hands off landscape, hire a gardener to periodically check your system out and is working properly.

You can work out what your plants need in evapo-transpiration (gal of water/day or week) from info from university research appropriate in your area. You need to research your drip system's flow rate( gal/min) and you can calculate how long each valve needs to stay open to deliver that amount. Then you check the drip plume pattern to see if your water gets to the all the roots. This takes probing the root zone and seeing what is going on. Your new landscaper should understand everything I have mentioned and be able to take you through all the calculation of his design and why he did what he did. JMHO. Aloha

Thanks again lehual: I was told that the organic amendments were dug in to about 24 inches and some of others like gypsum were tilled deeper as much as about 30 inches. The 80/20 reference is related to 80 percent topsoil and 20 percent decomposed granite. I understand he also used a product call 'Tufus' in some areas. It is exploded volcanic material used for baseball infields but is supposed to dramatically improve drainage and is more durable than perlite or vermiculite but serves the same function without the pulmonary toxicity problems. Our system has a sensor that gets a feed from our County's 'Water Wise' website and adjusts the systems automatically based on an index. It also has a mini weather station as a back-up which also feeds data into the system. I especially appreciate your advice about the need to inspect the brown, underground tubing for clogs. We will take care of that. Again, thanks for all of the great advice.

Sean,

You have received a top-of-the-line professional landscaping job, not your usual residential treatment. The "tufus" has very good water retention qualities to conserve water. De Nada mi amigo. Aloha.

Ask the installers why they did what they did.