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Wheat & Small Grains Timely Topics – Soil Management

Variable Rate Nitrogen Application – A Grower’s Perspective

The unique, hilly topography of the inland Pacific Northwest causes great within-field variability in soil and water conditions. As a result, crop yield potential and crop response to nitrogen (N) applications will vary according to the hillslope position, steepness, and aspect of any planted location. Thus, variable rate N (VRN) application makes sense for growers in this region.

In a recently published case study, Variable Rate Nitrogen Application: Eric Odberg, a grower from Genesee, Idaho, shares his 10 years of experience using VRN application in a direct seeding (no-till) system. Although transitioning to VRN application is a big decision with many challenges along the way, Eric’s 10 years of experience has brought him numerous benefits. These benefits include reduced fertilizer input, reduced lodging, reduced risk of N losses to the environment, and increased financial gain. Furthermore, because Eric complements VRN application with direct seeding and diversified crop rotations, his farm’s soil quality has also improved.


For questions or comments, contact Georgine Yorgey (yorgey@wsu.edu) or Sylvia Kantor by email at kantors@wsu.edu at the Center for Sustaining Agriculture and Nature Resources, Washington State University, or Kathleen Painter by email at kpainter@uidaho.edu at the Department of Agricultural Economics and Rural Sociology, University of Idaho.

A Win-Win: Building Soil Health While Gaining Yield & Profit

A 375-horsepower crawler tractor pulls a 1,000-gallon tank cart and a 32-foot-wide undercutter implement during primary spring tillage plus nitrogen and sulfur fertilizer injection in May. The undercutter’s narrow­-pitched and overlapping wide V-blades slice beneath the soil at a depth of five inches to completely sever capillary channels and halt the upward movement of liquid water to retain seed-zone water in summer fallow for late-summer planting of winter wheat. Most of the winter wheat residue from the previous crop is retained on the surface to control wind erosion.

Soil health and soil quality are two synonymous terms that are defined interchangeably by the Natural Resources Conservation Service (NRCS) as follows: “Soil health, also referred to as soil quality, is the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”. As a complicated bioecological system, soil is a living system with an abundance of diverse bacteria, fungi, and other microbes that have significant effects on soil physical and biological properties. Healthy soils provide a healthy physical, chemical, and biological environment for optimal crop growth.

Inherent soil properties that contribute to soil health, such as soil texture, are determined by the natural parent material and the environmental conditions during soil formation, in the absence of human impacts. Soil health is dynamic, rather than static, and can be degraded or improved with time as a result of soil use and management by humans. Soil degradation causes soil organic matter, fertility, structure, and biodiversity to decline and soil acidification to increase. As a result, crop productivity can decrease, crop diseases and weed problems can increase, and environmental quality can suffer.

Building soil health is becoming increasingly important worldwide. Soil imbalances in essential crop nutrients can be addressed by applying fertilizer and organic amendments. And soil chemical, physical, and biological properties can be significantly improved by adopting management practices such as no-tillage or reduced tillage.

A recently published article, Best Management Practices for Summer Fallow in the World’s Driest Rainfed Wheat Region, compares the effects of three fallow management practices on soil water dynamics, wheat stand establishment, grain yield, and economic returns. This research was conducted on two farms in the driest rainfed wheat production region in Washington (WA). At the drier site, results from the 5-year study indicated that late-planted winter wheat on no-tillage fallow was as profitable as on tilled fallow. Additionally, the study found that, at the slightly wetter site, undercutter tillage resulted in equal or greater grain yield compared with both traditional tillage and no-tillage.

Another recently published article, Wheat Farmers Adopt the Undercutter Fallow Method to Reduce Wind Erosion and Sustain Profits, surveyed 47 farmers who had been practicing undercutter tillage for several years. Farms were located in the low-rainfall (< 12 inches annually) zone of east-central WA and north-central Oregon (OR). Interviewers asked farmers to compare the agronomic and economic performance between undercutter tillage and conventional tillage. Results of this survey concluded that, on average, undercutter and conventional tillage systems have equal profitability. However, the undercutter system offers a costless air quality gain and a soil health benefit in terms of reducing wind erosion.


For questions or comments, contact Dr. Douglas L. Young (dlyoung@wsu.edu), Professor, in the School of Economic Sciences, or Dr. Bill Schillinger (William.schillinger@wsu.edu), Professor, in the Department of Crop and Soil Sciences at the Washington State University.

 

Adjusting Wheat-Based Management Strategies for Oilseed Production

Field of canola.

Oilseeds, such as canola, are recognized as rotational crops that can benefit the agro-ecological and social-ecological systems within the traditional wheat-based cropping region of the inland Northwest Pacific. Although farmers can continue to use wheat-based farm equipment, management practices need to be adjusted specifically to canola physiology and morphology to optimize yield and quality.

A recently published article, Physiology Matters: Adjusting Wheat-Based Management Strategies for Oilseed Production, compares the physiological and morphological characteristics between wheat and oilseeds. Characteristics studied included the differences in seed size, shoot meristem, cold tolerance, and above and below ground morphology. Based on these differences, the article provides recommendations for modifying wheat management strategies, for example, planting date and fertility management, for canola production.


For questions or comments, contact Dr. William Pan at wlpan@wsu.edu or Karen Sowers at ksowers@wsu.edu.

New Publication Addresses Acidic Soils and How They Interact with Root Diseases

As soil acidification continues to be a concern for growers in the Pacific Northwest, WSU researchers are working to provide information and recommendations for how to mitigate adverse effects. Root diseases are one of many factors influenced by acid soils, depending on the soilborne pathogen. The new publication, Acid Soils: How Do They Interact with Root Diseases?, explains how soil pH affects root diseases and also offers examples of common ones in the Pacific Northwest.

Cereal growers in the Pacific Northwest have been experiencing an increase in soil acidity (lower pH) primarily due to a long history of ammonium fertilizer use.

In eastern Washington and northern Idaho, soil acidification tends to be worse in areas that are annually cropped, do not include nitrogen-fixing legumes in the crop rotation, and in areas that were historically forested. Forested soils tend to have a lower pH buffering capacity, making them more prone to shifts in soil pH. These same areas also typically include more forage and seed grass production and seldom include legumes in rotation, meaning that there is more intensive nitrogen application to the soil.

In addition, direct seeding can result in a stratification of soil pH in which the top few inches of soil are more acidic. This is because acidification caused by fertilizer application in the top soil layers is not diluted by mixing with the more alkaline soil below the fertilizer zone. However, the contribution of this stratification on management of soil acidity in direct-seed systems has not been evaluated.


For questions or comments, contact Tim Paulitz at USDA-ARS Wheat Health, Genetics and Quality Research Unit (paulitz@wsu.edu or timothy.paulitz@ars.usda.gov) or Kurtis Schroeder, Assistant Professor in the Department of Plant, Soil, and Entomological Sciences at the University of Idaho (kscroeder@uidaho.edu).

Soil Acidification Video Series

Awareness of soil acidification has been growing in the inland Pacific Northwest (iPNW). Farmers, Researchers, and Industry Professionals have been finding that this emerging regional issue has generated more questions than answers. Soil acidification can affect crops and nutrient availability, as well as pathogens and herbicide use. Growers faced with low pH soil can be challenged by the question of what to do about it.

WSU Extension has released a series of three short videos featuring growers and local researchers explaining the challenges, symptoms, causes, and implications for farm management that are associated with soil pH decline.


“Soil Acidity- What it looks like” this video focuses on the symptomology of crops being affected by low soil pH, and other factors that may confound identification of acidic soil.


“Soil Acidity- How it happens” this video focuses on why the Palouse region is experiencing a decline in soil pH, and how it is often seen distributed through the landscape and soil profile.


“Soil Acidity- managing it on the farm” this video discusses how low pH soil can affect management decisions on the farm, and ways of mitigating the impact of soil acidity on crops.


For questions contact Carol McFarland at carol.mcfarland@wsu.edu.

Washington State University