Lasagna mulching

The next two weeks I'll be doing lasagna mulching at some of the centers. This is an easy way to prepare new garden beds or build soil for older ones, without digging up sod or pulling weeds (although you want to remove some weeds such as blackberry, bindweed, morning glory or quackgrass, which the layering process won't smother).

Lasagna mulching consists of alternating layering sources of carbon & nitrogen. You want to start about 6 months before you intend on planting, to allow the materials to fully decompose. We'll be doing this for the beds we plant in later in the spring.
First mow the grass as low as possible. The you start with layering several sheets of cardboard (a carbon source) over your future bed; this will block out sunlight and smother the grass. Wet the cardboard thoroughly, then add a 1 inch layer of nitrogen, followed by a 1 inch layer of carbon. Repeat the layering or nitrogen and carbon 3 times and end with a layer or carbon. On top of this you can layer some burlap sacks and cover with black plastic. In about 4-6 months, remove the plastic and check to see if the materials have fully decomposed. The burlap sacks will also decompose, but if they are taking too long you can removed and compost them. The rest should like and smell like fresh soil when it is ready. The add some compost and get to planting!

Sources of carbon: sawdust, leaves, corn stalks, pine needles, peat moss, newspaper, cardboard, straw and hay.

Sources of nitrogen: coffee grounds, kitchen scraps, composted manures, alfalfa pellets, vegetable scraps, fresh grass clippings and cottonseed, soybean and blood meal.

We received all our supplies for this project for free:
*Cardboard- in large quantities from Costco
*Coffee grinds- starbucks
*Carbon- leaves (I didn't even have to collect them myself, I put an add on craigslist & someone was happy for me to take their bagged leaves of their hands)
*Burlap sacks- stumptown coffee roasters.

Since I am using coffee grinds as a nitrogen source, it will acidify the soil, so I will be adding lime over the top layer of carbon.

For more information check out the OSU extension's resources:
http://extension.oregonstate.edu/news/story.php?S_No=1080&storyType=garden

http://extension.oregonstate.edu/lane/sites/default/files/documents/Lasagna.pdf