Paul Wheaton and Michael Pilarski (Skeeter) talk about keyline systems. A keyline system uses a keyline plow and spreads water throughout the landscape, rather than letting it only accumulate in vallies. The goal is for the landscape to become a big sponge. A keyline plow is a subsoil plow that has a "shakerator." It takes 3-4 years to get the land thoroughly subsoiled, gradually deeper and deeper. It helps to reverse soil compaction. This is one way to replace irrigation with permaculture. You can double your rich topsoil in 4 years with the step-wise manner, especially if you have clay soil. It incredibly accelerates topsoil formation.
The plow makes a series of little trenches/cracks that are every 3 feet or so, and go into the subsoil. Extra runoff can be saved in farm ponds for irrigating during drought. You can irrigate quickly and evenly, which is great in conventional agriculture. Some keyline plowing will be demonstrated on Monday after the Inland Northwest Permaculture Conference. Skeeter says that with keyline plowing, you can gain a month or two in a season because the soil warms earlier. Aeration allows the soil to breathe, and it has a bit of frost protection.
Skeeter points out that you can drop seeds in the channels that form. Paul and Skeeter talk about the importance of not having tractors or livestock out when it's wet as they will compact the soil. Paul brings up Allan Savory's work in this area. Skeeter suggests keyline plows be bought and shared by communities of farmers in a cooperative manner. Some of the big players in the field are Daren Doherty, Geoff Lawton, Eric Artapple Smith (spelling?), and Neil Bertrando, who is coming to the conference. P.A. Yeoman has several books out: Water for Every Farm, one on doing keyline in urban situations, and The Challenge of Landscaping. You can find this information at the Soil and Health Library. Lastly, Skeeter reminds people of his PDC at the end of April, 2012, right before Sepp Holzer comes to Montana.