William Pan

Washington State University | WSU · Department of Crop and Soil Sciences

Deep soil health (>30 cm) supports deep roots in dryland wheat cropping systems. However, few studies examine how tillage and climate impact soil health indicators deeper than 30 cm in dryland wheat systems. We evaluated how select soil chemical (i.e., nutrients and pH), biological (i.e., carbon [C] and nitrogen [N] fractions and ratios), and physi...

Canopy temperature (CT) is considered a reliable proxy for stomatal conductance. Low CT values of plant canopies under water-limited conditions are associated with high transpiration indicating plants’ drought tolerance. Many U.S. Pacific Northwest (PNW) adapted wheat (Triticum aestivum L.) cultivars lack stress-adaptive traits resulting in poor pe...

Winter canola (WC) offers not only marketable products but also excellent rotational benefits through disease, weed, and pest control in the dryland cropping systems of the inland Pacific Northwest (iPNW). However, little regional fertility research has been conducted on WC. The objectives of this study were to (i) determine the influence of soil N...

Improvements in market value of hard red spring wheat (HRS, Triticum aestivum L.) are linked to breeding efforts to increase grain protein concentration (GPC). Numerous studies have been conducted on the identification, isolation of a chromosome region (Gpc-B1) of Wild emmer wheat (Triticum turgidum spp. dicoccoides) and its introgression into comm...

Dense subsoils pose a challenge to dryland winter wheat (Triticum aestivum L.) production in the Palouse region of the semiarid northwestern United States. Subsoils, commonly fragipans and argillic horizons, may restrict root growth and limit crop access to critical stored soil water, but this phenomenon is not well characterized in the Palouse. Du...

In the semiarid dryland wheat (Triticum aestivum L.) region of the U.S. inland Pacific Northwest, winter canola (WC) (Brassica napus L.) is an economically viable rotation crop. Winter canola produces marketable end‐products while improving soil health and disrupting pest and disease cycles. Although annual production of WC in Washington State has...

High resolution computer imaging was developed to evaluate the root dynamics of a biofuel plant—castor bean in a plastic container. Root growth dynamics of the plant was evaluated to determine root and root hair morphology and responses to a particular soil at various time intervals with soil depth. High resolution (2400 picture elements (pixels) c...

Banding of N fertilizers below the seed is a common practice in direct seeded wheat dominated dryland agricultural systems, yet the placement of fertilizer below the seed has been shown to decrease yields and damage the root system architecture (RSA) in canola (Brassica napus). However, there is a lack of understanding as to which rates and sources...

With the addition of nitrogen (N), agricultural soils are the main anthropogenic source of N2O, but high spatial and temporal variabilities make N2O emissions difficult to characterize at the field scale. This study used flux‐gradient measurements to continuously monitor N2O emissions at two agricultural fields under different management regimes in...

Soil acidification caused by long‐term nitrogen (N) fertilizer applications has been a growing concern for dryland crop production in both tilled and no‐till soils in the Pacific Northwest (PNW). Many no‐till soils have stratified soil pH in the 5‐10 cm depth due to repeated N fertilizer applications at this depth. In the PNW, the practice of limin...

Raindrop‐induced crusting of mineral soils supporting wheat ( Triticum aestivum L.) in the semiarid US Pacific Northwest reduces seedling establishment of late summer‐seeded winter crops during dry, hot conditions. Canola ( Brassica napus L.) integration is diversifying regional food, feed and fuel global markets. Subsequent shifts in recycled crop...

Camelina (Camelina sativa L. Crantz) is highly sensitive to soil residual levels of many acetolactate synthesis (ALS) inhibitor herbicides. Other crops with resistance to these herbicides have been developed through mutation. Development of camelina with this resistance would allow greater flexibility for the crop in rotation with other crops. The...

The long-term sustainability of wheat-based dryland cropping systems in the Inland Pacific Northwest (IPNW) of the United States depends on how these systems adapt to climate change. Climate models project warming with slight increases in winter precipitation but drier summers for the IPNW. These conditions combined with elevated atmospheric CO2, w...

Core Ideas Use of a stripper header to leave tall stubble for high‐residue no‐till. Winter triticale outperforms winter wheat in low rainfall dryland production. Tall crop residue reduces wind speeds at the soil surface. The low‐rainfall wheat production zone of eastern Washington is subject to wind erosion because of fine‐textured soils, low soil...

Cropland is an important land cover influencing global carbon and water cycles. Variability of agricultural carbon and water fluxes depends on crop species, management practices, soil characteristics, and climatic conditions. In the context of climate change, it is critical to quantify the long-term effects of these environmental drivers and farmin...

Interactive effects of weather and soil nutrient status often control crop productivity. An experiment was conducted to determine effects of N and S fertilizer rate, soil water, and atmospheric temperature on canola fatty acid (FA), total oil, protein and grain yield. Nitrogen and S were assessed in a 4-yr study with two locations, five N rates and...

Inter‐seasonal N carryover increased subsequent crop N recovery. Increases in yield and N uptake after pea were partly attributed to higher N supply. The benefit of pea preceding winter wheat increased with increasing available water. Constructed rotation N balances incorporated inter‐seasonal changes in soil N supply. Rotational N use was modeled...

Core Ideas Biosolids N contribute to wheat grain and soil N. Applied biosolids contain light fraction and non‐hydrolyzable C and N. Biosolids C efficiently increased soil C at 0.91 Mg C in soil per Mg C in added biosolids. Buildup of non‐hydrolyzable, high C:N light fraction originates in light density biosolids. High total and non‐hydrolyzable C r...

Climate-friendly best management practices for mitigating and adapting to climate change (cfBMPs) include changes in crop rotation, soil management and resource use. Determined largely by precipitation gradients, specific agroecological systems in the inland Pacific Northwestern U.S. (iPNW) feature different practices across the region. Historicall...

Ecological instability and low resource use efficiencies are concerns for the long-term productivity of conventional cereal monoculture systems, particularly those threatened by projected climate change. Crop intensification, diversification, reduced tillage, and variable N management are among strategies proposed to mitigate and adapt to climate s...

Accurate carbon and water flux simulations for croplands are greatly dependent on high quality representation of management practices and meteorological conditions, which are key drivers of the surface-atmosphere exchange processes. Fourteen site-years of carbon and water fluxes were simulated using the CropSyst model over four agricultural sites i...

Canola is a new crop for many inland Pacific Northwest U.S. wheat growers to consider for integration into their wheat-dominated systems. Both crops have winter and spring varieties that can fill niches in different precipitation zones across the region, and they both efficiently extract available water to depths of 4 to 6 ft if soil depth allows....

The productivity of semi-arid, cereal-based agroecosystems is inherently limited by water and nutrient availability, with water limitations expected to be exacerbated by climate change. While previous studies have identified agronomic, economic, and environmental benefits of rotating oilseed, pulse, and cover crops with cereals for mitigating the e...

Diversification and intensification of inland Pacific Northwest (PNW) dryland cereal cropping systems can present win-win scenarios that deliver short and long-term benefits for producers and the environment, stabilizing profit and increasing adaptability to and mitigation of climate change. Improving diversity, or reducing fallow, can enhance curr...

Ammoniacal fertilizers can cause seedling damage. The present aims were to characterize spatial and temporal, root morphological NH 3 /NH 4 ⁺ toxicity symptoms, assess the extent of the toxicity zone, and relate species‐specific responses to their root architecture. Wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) were exposed to seed...

Nitrogen fertilizer requirements for economic optimization of spring canola ( Brassica napus L.) production in eastern Washington varies with yield potential. Recent research has revealed that more N is needed per unit of grain (UNR) as yield potential decreases. Because UNR is the inverse of N use efficiency (NUE) at optimal yield, the implication...

Prospects for canola (Brassica napus L.), as a rotational crop for agronomic and market diversification, have stimulated agronomic research to fit this crop into the unique environments and soils where wheat (Triticum aestivum L.) production dominates. The objectives of the present study were to define N and water requirements of canola following w...

This report addresses the development of dryland oilseed crops to provide feedstock for production of biofuels in semi-arid portions of the northwestern USA. Bioenergy feedstocks derived from Brassica oilseed crops have been considered for production of hydrotreated renewable jet fuel, but crop growth and yields in the northwestern region are limit...

Expansion of biofuel cropping systems requires better spatial resolution of life cycle greenhouse gas (GHG) emissions and mitigation potentials. Simulation modeling was carried out to understand the impact of agro-ecological zone (AEZ), and nitrogen (N) use efficiency (NUE) for inland Pacific Northwest canola and Midwestern soybean biodiesel GHG mi...

Agricultural soils have the potential to be an important carbon (C) sink with proper management. The main goal of this study was to characterize C dynamics and net C exchange over two full crop years at two sites in the inland Pacific Northwest (iPNW). The iPNW is a highly productive dryland wheat growing region. The two measurement sites represent...

Analysis of carbon and water budgets in cropping systems is important for understanding the impacts of different management practices and meteorological conditions, in the context of climate change, on agriculture. We have established a pair of long-term eddy covariance flux towers at the R. J. Cook Agronomy Farm (CAF) near Pullman, Washington, US....

Prospects for canola ( Brassica napus L.), as a rotational crop for agronomic and market diversification, have stimulated agronomic research to fit this crop into the unique environments and soils where wheat ( Triticum aestivum L.) production dominates. The objectives of the present study were to define N and water requirements of canola following...

The inland Pacific Northwestern USA (iPNW) wheat-producing region has a diversity of environments and soils, yet it lacks crop diversity and is one of the few semi-arid wheat-growing regions without significant integration of oilseeds. Four major agroecological zones, primarily characterised by water availability, feature distinctly different fallo...

Winter wheat (Triticum aestivum L.)- summer fallow (WWF) has been the prevalent rotation in the low rainfall zone of the Pacific Northwest (PNW) for more than 130 years; however, this rotation is characterized by poor soil health, high pest incidence, and poor environmental sustainability. A 6-year study was initiated in 1995 to evaluate the agrono...

Winter varieties of canola (Brassica napus L.) are susceptible to winterkill. Measurements of photosynthetic efficiency and survival of field-grown canola were used to evaluate the effect of chloride (Cl), potassium (K), and phosphorus (P) nutrition on winter field survival in northwestern USA. In a growth chamber experiment, effects of calcium chl...

Faba bean (Vicia faba L.) is a versatile crop grown for food, feed, vegetable, or cover crop purposes in many countries. In response to the growing demand for winter annual legumes for cover crop development in the United States, we developed four winter-hardy faba bean germplasm lines, WH-1 (Reg. No. GP-3, PI 674326), WH-2 (Reg. No. GP-4, PI 67432...

An indoor pot culture experiment was conducted in the growth chamber during the period of vegetative growth to evaluate the influence of inorganic nitrogen fertilizer in the form of urea on nutrient uptake, growth and root development of castor bean plant. The Nitrogen Fertilizer treatments imposed in the experiment were: Control (N0), no nitrogen...

This study documents the importance of soil fertility in the dryland farming areas of Idaho, Oregon, and Washington. Mail-based surveys conducted in 1981, 1996, and 2011 were used to document the importance placed on soil fertility by farmers. The significant findings of the 2011 survey were (1) more than 62% of the growers attributed more than 50%...

Growers in the low‐rainfall, winter wheat–summer fallow region of the Pacific Northwest (PNW) need an alternative crop to diversify markets, manage pests, and increase wheat yields. Winter canola may be a viable option for this region. However, agronomic research for winter canola in this region has not been conducted, and growers are reluctant to...

RÉSUMÉ Les sols irrigués dans le bassin de la rivière Columbia dans l'est de l'état de Washington sont sensibles à l'érosion éolienne et à la percolation des nitrates lorsque laissés nus au cours des mois d'hiver. On encourage les producteurs à incorporer des récoltes de couverture dans leurs rotations ou à laisser les résidus de récoltes sur leurs...

Growers in the low-rainfall, winter wheat (Triticum aestivum L.)–summer fallow region of the Pacific Northwest (PNW) need an alternative crop to diversify markets, manage pests, and increase wheat yields. Winter canola (Brassica napus L.) may be a viable option for this region. However, agronomic research for winter canola in this region has not be...

Because of growing consumer concern about the use of antimicrobials and the ban on most antibiotic feed additives in the European Union, there is increased interest in using alternatives to antimicrobials in poultry diets. Dried leaves of Artemisia annua have been used in Oriental medicine due to their antimicrobial activities. In the current study...

Accurate estimates of soil organic C (SOC) stocks are required to determine changes in SOC resulting from agricultural management practices. Our objectives were to: (i) determine total SOC; (ii) estimate the contribution of light fraction C (LF-C) to total SOC; and (iii) simulate SOC dynamics using CQESTR to examine the effect of climate change for...

A multi-year cropping systems study under no-tillage was initiated in 1999 on a 37-ha field of the WSU Cook Agronomy Farm near Pullman, WA. The study objectives are to: (1) evaluate continuous no-tillage and crop rotation effects on total profile soil nitrogen (N) and (2) relate changes in total soil N to N inputs from fertilizer, N outputs in harv...

It is becoming increasingly important to investigate the relationship between global climate and agriculture in the face of ongoing climate change and the need to feed a growing global population. The REgional Approaches to Climate CHange (REACCH) USDA-NIFA project is focused on Inland Pacific Northwest cereal cropping systems with an overarching g...

Maintaining soil organic carbon (SOC) is a major factor in sustaining crop yield and biomass production in the low precipitation zone of the dryland Pacific Northwest (PNW) in the United States (U.S). Our objectives were to (1) determine SOC stocks under various cropping systems in the eastern PNW region (Ralston, Adams County in Washington, U.S.),...

Biodiesel production has increased demand for oilseeds such as canola, which can be grown in crop rotation with wheat and barley. Winter canola, when seeded in spring or early summer, will grow as a biennial crop that allows for a forage crop to be harvested in yr 1. The aim of this experiment was to evaluate biennial canola as a dryland forage for...

Nonpoint sources account for nearly two-thirds of nutrient loading to the nation's surface waters (Beutel et al., 2009; Sharpley et al., 2001). Vegetated filter strips can mitigate the effects of agricultural activities by presenting a physical barrier to sediment, nutrients, and pesticides being carried into streams (Munoz-Carpena and Parsons, 200...

Agroecological zones (AEZ's) have traditionally been defined by integrating multiple layers of biophysical (e.g. climate, soil, terrain) and occasionally socioeconomic data to create unique zones with specific ranges of land use constraints and potentials. Our approach to defining AEZ's assumes that current agricultural land uses have emerged as a...

The long-term environmental and economic sustainability of agriculture in the Inland Pacific Northwest (northern Idaho, north central Oregon, and eastern Washington) depends upon improving agricultural management, technology, and policy to enable adaptation to climate change and to help realize agriculture's potential to contribute to climate chang...

The purpose of this guide is to summarize current information on canola growth and fertilizer requirements. Canola is a relatively new crop to the Pacific Northwest and little fertility research has been conducted in this region. The information contained in this guide is intended to serve as a reference until the results of ongoing, local research...

Since nitrogen (N) and sulfur (S) are major components of protein and the enzyme complexes acetyl-CoA carboxylase and fatty acid synthase are responsible for oil or fatty acid biosynthesis, it is expected that soil and fertilizer N and S will affect canola grain protein content, fatty acid content, and fatty acid profile (Somerville et al., 2000)....

An imaging method was developed to evaluate crop species differences in root hair morphology using high resolution scanners, and to determine if the method could also detect root hair responses to soil water availability. High resolution (1890 picture elements (pixels) cm−1) desktop scanners were buried in containers filled with soil to characteriz...

A mesorhizotron and scanning system was modified to study the development of Russian thistle root systems during the 1996 and 1997 growing seasons at Lind, WA. Our imaging equipment combined the full profile images afforded by conventional rhizotrons with the portability of cylinder- based minirhizotron systems at a fraction of the cost of either s...

Understanding crop root morphology will enable better understanding of nutrient uptake efficiency and ultimately improve crop management. The ability to observe the rhizosphere with high resolution scanners will allow characterization of root-soil interactions in real-time. High resolution (4800 dpi) desktop scanners were buried in containers fille...

Iraq, formerly known as Mesopotamia, is the birthplace of agriculture. The recent war and instability have significantly impacted the country's agricultural production and knowledge support systems. To support revitalization of the Iraqi agricultural system, the USDA funded a consortium of five U.S. universities (Washington State University, Univer...

In the dryland agriculture areas of the Pacific Northwest, where wheat (Triticum aestivum) cultivation dominates, farmers have few rotational crops at their disposal. Oilseed producing crops, along with serving as biodiesel feedstock, may also serve as alternative rotational crops. Understanding the root structures and their respective rhizospheres...

Wastes from straw pulping in paper manufacturing can be used as soil amendments depending on their chemical composition. Polysaccharides and lignin, the major organic components of these products, are potentially important in soil aggregation. Incubation Studies were conducted to determine (i) the extent of soil water-stable macroaggregate (WSM) fo...

The 3.3 million hectare tri-state dryland crop production region of the Pacific Northwest (PNW) is divided into three general cropping system zones; high precipitation (45-60 cm), intermediate precipitation (30-45 cm), and low precipitation (<30 cm), with the majority of precipitation occurring during the winter months. The climate and soils of the...

The cereal and grass seed cropping systems of the Pacific northwestern USA generate a valuable fiber source for papermaking. Pulping straw with KOH produces black liquor, an organic waste effluent with potential as a K source and soil amendment. The objectives of this study were to determine if black liquor from wheat straw pulping with KOH improve...

Lignin contained in pulping liquor that is generated during the pulping process for papermaking is a disposal problem for the pulp and paper industry. Separating lignin and other organic components from pulping liquor with inorganic acids may improve its applicability to fields as a beneficial soil amendment while offering a potential disposal alte...

W. L. 2006. Pulp and paper mill by-products as soil amendments and plant nutrient sources. Can. J. Soil Sci. 86: 641–653. Pulp and paper mill sludges are produced from primary and secondary treatment of wastes derived from virgin wood fiber sources, recycled paper products, and non-wood fibers. Sludges and sludge composts may be utilized in agricul...

Sodium-based black liquor from fiber pulping for papermaking creates challenging waste disposal issues. By substituting NaOH with KOH in the pulping process, the resulting black liquors may be land applied as an environmentally beneficial disposal alternative. Incuba- tion studies examined the effect of KOH-based black liquor on soil pH, electrical...

Plexiglass pot growth chamber experiments were conducted to evaluate the chemical alterations in the rhizosphere of mycorrhizal wheat roots after inoculation with Glomus intraradices [arbuscular mycorrhizal fungus (AMF)]. Exchange resins were used as sinks for nutrients to determine whether the inoculated plant can increase the solubility and the u...

Improving nitrogen use efficiency (NUE) is an important objective of agroecosystem management. We define and demonstrate key indicators of NUE that enable a broader assessment of N management strategies. Nitrogen efficiency components and indexes were defined to assess soil and crop physiological processes, and agronomic and environmental factors r...

This analysis determines profit‐maximizing N fertilization levels of hard red spring wheat (HRSW) ( Triticum aestivum L.) for various wheat prices, N prices, and protein‐based HRSW price premium/discount (P/D) structures for southeastern Washington data. Fertilizer response data consisting of rates of N fertilization (kg ha ⁻¹ ), grain yield (kg ha...