By Karen Hills

A frequently used—at least, by soil scientists—definition for soil health is “the continued capacity of soil to function as a vital living system […] to sustain biological productivity, maintain the quality of air and water environments, and promote plant, animal, and human health” (Doran et al. 1996). Many different indicators—chemical, physical, and biological—are used to assess soil health.

Figure 1. Potatoes are economically important crops in many irrigated areas of the Pacific Northwest. Here, potatoes are harvested near Pasco, Washington. Photo: Athena Loos.

Growing potatoes is notoriously hard on the physical and biological health of soil (Figure 1). Potato production in many areas of the Pacific Northwest involves seven or more soil disturbance operations, leaves little residue on the field, and often involves the use of fumigants to control soilborne diseases. The economics of potato production often drive growers to utilize short rotations. But a suite of strategies are possible to improve soil health in potato production, including cover crops, rotating with perennial crops and crops that contribute high levels of residues, and incorporation of organic amendments. While growing green manure crops for biofumigation has probably achieved the most success and adoption in the region (see producer Dale Gies as an example), in this article I focus on a more challenging strategy that has received limited attention, but may have more direct climate change implications: tillage reduction. Continue reading →

by Georgine Yorgey

Managing crop residue is essential to reduced and no-till farming systems. These farming systems store more carbon than conventional farming systems, thereby mitigating climate change, enhancing soil health, and reducing soil erosion. In work described in a recent project report, Arron Carter and colleagues have been working to make it easier for growers with diverse needs across the Pacific Northwest to manage wheat residues. While the work is still in progress, it is an illustration of the kind of creative, applied work that is needed to make reduced-tillage systems easier to manage, and more widely adopted across the region.

Wheat residue in a field in early July near Bickleton, WA. This area is part of the drier winter wheat-fallow area, where slower decomposing residues are preferred. Photo: Hilary Davis.

Growers in different parts of the dryland Pacific Northwest are seeking different residue characteristics. Continue reading →

By Georgine Yorgey

Topsoil has often been referred to as the “thin skin” of our planet, essential for producing the food that feeds us. Because it’s not easy to create new topsoil, conserving the soil that we have is essential for maintaining our region’s agricultural productivity. Reducing tillage, and leaving residue on the soil surface, is a proven way to reduce erosion. As residues break down, they increase the concentration of soil organic matter at the surface of the soil and help to form soil aggregates—a composite of soil particles that clump or bind together, giving soil its structure. Soil that is aggregated in larger particles is less prone to being eroded by the wind. And soils with more organic matter also benefit the climate, by storing more carbon.

Planting the wheat cover crop in strips makes planting corn easier, as the planter does not encounter roots and leaves in the planting strip. Photo: Darrell Kilgore

Continue reading →

By Karen Hills

In non-irrigated areas that are too dry to support annual cropping, fallow (the practice of leaving land unplanted) preserves soil moisture for future crops. However, annual fallow combined with conventional tillage has resulted in a net decrease in soil carbon over time in our region, with negative impacts to soil health across large areas. And even when tillage is eliminated, it is very difficult to maintain soil carbon over time in a wheat-fallow system.  For this reason, the impact of climate change on the frequency of fallow in crop rotations has important future implications both for soil health and for opportunities for carbon sequestration.

Two papers published last year by Kaur et al. and Karimi et al. use modeling to project the impacts of climate change on dryland cropping systems. Continue reading →

By Georgine Yorgey

Farmer and long-time CSANR advisory committee member, Dale Gies. Photo: Sylvia Kantor.

What are the climate impacts of a given farm practice?  While we know lots of strategies for reducing greenhouse gas emissions on farms, quantifying that impact can be difficult.  However, there is at least one farm in our region – one that uses some pretty neat practices – for which scientists have attempted to answer that question.  And the farmer just happens to be a long-time member of the Center for Sustaining Agriculture and Natural Resources’ advisory committee, Dale Gies. Continue reading →