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Building Soils for Better Crops Conference

December 10, 2014, Big Bend Community College, Moses Lake, WA

Sponsored by WSU Grant-Adams Extension and Center for Sustaining Agriculture and Natural Resources.

This conference is the fourth in a series since 2006 focusing on the soil resource that is critical to sustained agricultural production in the Columbia Basin. Interest in “soil quality” and “soil health” has grown among growers, consultants, and the public at large. The soils in the Columbia Basin and their management are somewhat unique compared to the Midwest where most concepts of soil quality have developed. Prior to irrigation, most Basin soils had very low levels of soil organic matter (or organic carbon) as the low precipitation limits plant growth and residue return. The soils are also quite young (since the last Ice Age) and generally low in clay content, which is important for retaining added organic matter. Since irrigation, soil organic matter levels have increased with the large increase in plant biomass production. How high they might go, especially with added amendments such as manure or compost, is not clear. But they may seldom reach levels proposed by some as a threshold for “healthy soil” (2.5% organic matter). The workshops have focused on management practices and strategies that growers can use to enhance the soil resource, and experience improved crop production and better resource conservation.

Most of the presentations were recorded with PowerPoint plus audio. They can be viewed as YouTube files. This format allows for people who did not attend the conference to benefit from the presentations they are interested in, as well as those who did attend to revisit important points they want to understand better. The compost panel at the end was not recorded.


9:00 – 9:25 Introduction, context and questions

Andy McGuire, WSU CSANR

9:25 – 10:15 Soil Health for Disease Suppression

Lindsey du Toit, WSU NWREC/Plant pathology, Mount Vernon, WA.

Soil health – biological, chemical, and physical – can directly influence the occurrence and severity of certain soil-borne diseases. Examples of practices to shift soils to a more disease suppressive condition are provided for spinach, peas, and onions. In addition, ways to promote the beneficial mycorrhizal fungi are discussed.

Keywords: soil health; soil-borne disease; Fusarium; Rhizoctonia; mycorrhizae


10:30 – 11:20 Biological Indicators of Soil Health

Dan Sullivan, Crop & Soil Science Dept., Oregon State University, Corvallis, OR.

There is strong interest in a single “number” for soil health, but such an indicator does not exist. The presentation is organized around a series of questions to ask when looking for biological indicators, including organic matter levels, respiration and food web measurements as indicators, and the practical value of such indicators to growers. Some challenges and ideas related to biological indicators are presented.

Keywords: soil biology, biological indicators, respiration, food web,  soil organic matter, soil test correlation, Haney test


11:20 – 11:50 The Economics of Building Soils; Early Results from a Columbia Basin Study

David Granatstein, WSU CSANR/ Extension, Wenatchee, WA

Reports on the economics of soil quality improvement are scarce, and thus it can be difficult for growers to determine whether certain soil improvement practices make economic sense. A study of soil improving practices in the Columbia Basin, Washington State, was conducted used grower focus groups to look at organic amendments, cover crop/green manure, and high residue farming (reduced tillage). Based on the grower responses, all three practices had short-term (1-2 years) net economic benefit ranging from $15-200/acre. Thus, investing in soil for the long-term can make financial sense in the short-term.

Keywords: economics, partial budget, costs, benefits, organic amendments, green manure, reduced tillage


11:45 – Noon Discussion and questions


12:50 – 1:40 Factors Affecting Soil Organic Matter Levels

Stewart Wuest, USDA Agricultural Research Service, Pendleton, OR.

Extensive research has been done on soil organic matter, its composition, and how management can increase or reduce it over time. Organic matter is especially important in influencing surface physical properties such as water infiltration. Some amendments add more stable organic matter than others, while tillage generally reduces organic matter. It may be that in our warm dry climate, organic matter concentrated at the surface (residue, mulch) gives the greatest benefit rather than trying to increase the organic matter content throughout the top 6 to 12 inches of soil.

Keywords: organic matter accumulation, organic matter loss, tillage, organic amendments, water infiltration, surface residue


1:40 – 2:30 Nutrient Availability and Soil Health

Dan Sullivan, Crop & Soil Science Dept., Oregon State University, Corvallis, OR.

Nutrient availability is influenced by the soil biology, one aspect of soil health. Addition and decomposition of organic matter influences nutrient availability, particularly for nitrogen. The importance of the C:N ratio is discussed, with examples of how to estimate available N from organic nutrient sources. The “Organic Fertilizer and Cover Crop Calculator” was developed as a practical tool to help growers manage their nutrients.

Keywords: soil fertility, soil nutrients, nitrogen cycle, C:N ratio, organic fertilizer calculator


2:45 – 3:35 Irrigated conservation agriculture in California

Jeff Mitchell, University of California


3:35 –4:25 Soil amendments for building soils in the Columbia Basin – Panel discussion

Aaron Jones, Cascade Agronomics LLC, Moses Lake, WA

Greg Ovenell, Ovenell Farms Inc., Quincy, WA

Chuck Graaff, Royal Organic Products, Royal City, WA


4:25 – 4:40 Discussion, questions and wrap-up

David Granatstein, WSU CSANR


Moderators and organizers: Andy McGuire and David Granatstein