starting soil from scratch

Asked February 4, 2017, 11:46 PM EST

We are starting a new garden. We recently moved to the area. Our soils are high in clay - I can dig 3 ft without any discernible horizons except the top litter. Is there an extension pub or resource to describe the portions of compost/topsoil/mulch/etc to get to start building a soil - also one about using cardboard or that black mat to minimize weeds? We will be using raised beds. We already have a small orchard and a soil test there had a ph of 5.6 and indicated a need for lime (which we did). thanks!

Benton County Oregon horticulture soil and fertility issues vegetable gardening

1 Response

Hello. Thank you for your question. There is in fact an excellent extension publication that talks about improving your soils. “Improving Soil with Organic Matter” EC 1561. Here is the link https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1561.pdf . If you are building raised beds for vegetable production there is another option to get you jump started if you have the funds, purchase a soil mix from a garden center to get started. Visit several places and look at the various mixes to see which meets your needs. These mixes will still benefit from periodic addition of organic materials so the above publication is still of value. I recommend you read it first and then do some visiting and make your decisions on what soil you put into your raised beds. I also have clay soils as most of us around here do. I can tell you that I have done both and was far happier with a purchased soil sooner. The native soils that I was so careful to amend with organic matter took several years to get to the same level of tilth and productivity. So, it depends on your pocketbook, your patience and your energy level.

Cardboard is a better option than an inorganic layer to suppress weeds as it builds the soil under it while the black mat does nothing for the soil underneath. Lay down a solid layer of cardboard, cover with several layers of newspaper and top with 2-3 inches of compost. The cardboard and newspaper will block the light and kill the plants covered (if they are tall mow down first). The compost layer will hold down the paper and cardboard and allow water to penetrate. The microbes and worms do the rest of the work. This takes several months before the area covered will be ready for planting and will give a good start on developing a great soil in the area covered. In subsequent years, a cover crop can be planted to protect the soil from the rains in the winter and suppress weeds during the winter after vegetable production is done. The cover crop will also help with loosening and building up the soil of you garden. I have included another link that will give you another extension publication on vegetable gardening called “Growing Your Own” https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9027.pdf Happy gardening!