Today I completed the basic installation of my Gray Water Irrigation system for my High Density Orchard. The system brings water from my surge tank (a rubbermaid garbage can) through a 400 micron filter (that only removes the really big stuff) and to the orchard via 3/4″ poly tubing.
In the above pictures the Surge tank and Filter is underneath the stairway in the first pic, the 3/4″ main line can be seen on the right hand side of all of the pics and it also runs along the fence line with the grapevines.
Once the Gray Water reaches the Orchard via the 3/4 poly line it is distributed throughout the planting area via 1/2″ dripper line. This dripper line has emitters spaced every 12″ along it’s length and I have spaced the lines every 4′ running generally with the contours of the area. What the heck does that mean? It means that the rows themselves are basically level but each row is lower down the slope of the land than the previous. Originally I thought my Orchard sloped from the NE corner down to the SW corner which would have forced me to orient the rows on the bias running NW-SE, but when I dug out the laser it showed that I had only a very slight E-W slope with the main slope being N-S. Consequently I ran my lines E-W, located 1′ N of each row of trees.
The first picture shows the layout of the emitter lines in relation to the trees, the following pics show the dispersal of the Gray Water from the emitters.
In a traditional drip irrigation system for a planting such as an orchard you would irrigate each individual tree with three or four emitters located in a circular pattern roughly at the drip-line of the tree. What’s the drip-line of the tree you say? It is the circle defined by where the rain would drip off of the leaves of the tree. This system is designed to water each individual tree, additionally common knowledge (which everyone knows ain’t necessarily correct) has it that this type of irrigation should be done slowly and infrequently to encourage deep root growth. This deep root growth is supposed to allow the tree to tap into buried sources of nutrients and provide a secure foundation.
Here we see the drip lines running down the rows of trees, which along this axis are spaced 9′ apart, the expanding area of moisture can also be seen developing in the second pic.
The traditional system works great when you are providing water solely for the purpose of irrigation, in my Orchard my water source is primarily a waste product from laundering clothes. This Gray Water is not storable due to the fact that it contains nutrients that will start to get funky in 24 hours or less. Also for a Gray Water system to work in the long run it must be as unobtrusive as possible, if the system requires thought and effort every time a load of clothes is going to be washed it ain’t gonna work!
Capillary action is the main theory my Orchards irrigation system is based on. Basically I am watering the entire 600 square foot area of my Orchard instead of the 24 seperate 4′ diameter circles around each tree. When I first started researching this concept it made absolutely no sense but the more I read the more the pieces came together from separate sources to reinforce what Paul James over at graywatergardening.com is preaching. What I am trying to achieve is an inviting biodynamic area for my trees to send roots out into. The moist areas seen expanding out from the lines in the pictures above is the result of approximately 80 gallons of Gray Water flowing through the system, by next weekend I’m hoping that normal laundry use and capillary action will result in uniformly moist soil over the entire area.
Then comes the mulch! Everything I am trying to emulate in my Orchard says that mulch is the key! Dave Wilson over at www.davewilson.com says it’s key to successful Back Yard Orchard Culture, Bob Morris at xtremehorticulture says it’s key to growing fruit in Las Vegas, and finally Paul James at graywatergardening.com says it’s key to having a safe and efficient Gray Water system. So next week I plan on hauling in mulch (ground up tree trimmings) and covering all of the area watered by the drip lines to a depth of at least 6″. Over time this will provide a fertile and ever improving soil for my trees to spread their roots into as the mulch slowly breaks down and is incorporated down into the soil by the natural action of earthworms, God’s little roto-tillers.