The Power of Mulch

By John Wallace, SIFT Farm Manager

We have had an oddly mild fall this year in Butte, Montana, which has led to a prolonged growing season. During this time, our perennial and over-wintering crops have not gone completely dormant. This could cause some negative issues, especially if you have already winterized your irrigation like we have. One way to protect your crops is to cover your plot with a thick layer of mulch. Mulching can help protect against weather extremes, keep moisture in, and minimize weeds. Because the ground is still active and has not frozen, all of these factors are still vital to the success of our crops.

Barley seeded from straw used to mulch strawberries on
the SIFT farm. Photo: NCAT.

There are many different organic materials you can use as mulch that are either a free resource or relatively cheap.

Cardboard or newspaper can be great for blocking weeds between beds; however, avoid using glossy pages or any metal-based ink. Newspaper will eventually break down and can then be turned into the soil. Though cardboard keeps water from evaporating out of the soil, it can create a hydrophobic layer, causing water to runoff rather than penetrate the ground.

Garden debris, such as leaves and pine needles, are often used to mulch. Pine needles will add acidity to the ground. This can be beneficial for crops that enjoy acidic soils, such as blueberries, or if you have an alkaline soil to begin with. Otherwise, you may want to monitor the pH of your soil and add lime to neutralize it if needed.

Straw is a great mulching material because it does not change the pH of your soil as it breaks down and does an excellent job of wicking moisture into the soil. When it comes to weed protection, straw acts as a good buffer between other weeds, but it often is filled with seed of its own.
On the SIFT Farm, we have learned that you must be wise when purchasing a straw bale because of that seed issue. Cereal ryes can overwinter, causing an outbreak of rye in your field the following year, whereas barley will die off in the winter. By using barley straw in the fall, we avoid the impacts of seed in the straw taking over the following year. In fact, this fall, it is acting as a living mulch that is drawing the precipitation directly the roots of our strawberry plants and helping to maintain more even soil temperatures. Like a cover crop, this will suppress other weeds and continue soil fertility in the fall, while our main crop grows simultaneously. Come next spring we will be left with the thatch that will break down into the soil giving way to our June-bearing strawberries.

Posted on: November 7th, 2016