Water Infiltration Demonstration
On July 3rd, 2009, a short demonstration was performed to show the infiltration properties of typical, valley clay soil. One area had been amended in place, and the other had been under a weed barrier cloth for years until just prior to the demonstration.
The test area had been a conventionally maintained lawn for at least 7 years prior to the amendment work at a residence in south San Jose California. The lawn was covered in a sheet mulching project. Compost and scrap corrugated cardboard as well as required mineral amendments were used for the sheet mulching. The soil was not turned or dug up in any way. The mulch layer had been in place for roughly 18 months preceeding this demonstration. The soil was severly compacted before the sheet mulching was applied. No infiltration measurements were taken before to the sheet mulching.
The control area is a park strip in front of a residence across the street from the test area. The park strip had been under a weed barrier cloth and a thin (less than 1") layer for mulch for roughly the same 7 year period. The weed barrier cloth and mulch had been removed approximately 1 month before the demonstration. The park strip had not been amended in any way.
The 7 minute video below shows the results.
If the video won't play, click here to view the video on YouTube.
One of the main benefits of the amended soil is how well it supports plants. If a swale or planted berm is required, the amended soil allows for plants to establish quickly and easily. If grass was required, the mulch layer would not have been added. Desired grasses could have been seeded into the amended soil or plugs or sod could be installed.