About
361
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Introduction
Dr. Sharon Clay is Distinguished Professor of Weed Science, Fellow of the American Society of Agronomy, former ASA president, technical editor for the Agronomy Journal, and associate editor for Weed Science. Her research is focused on on-farm research, weed/crop interactions, precision weed management, water quality, and the development of revegetative management plans for saline soils in the Northern Great Plains agricultural systems.
Additional affiliations
February 2016 - September 2016
February 2016 - August 2016
February 2016 - present
Education
March 1982 - May 1986
January 1979 - May 1982
September 1975 - May 1977
Publications
Publications (361)
Globally, agricultural scientists are challenged with creating, testing, and validating climate‐smart nutrient strategies that reduce greenhouse gas emissions while increasing food security. This study determined maize (Zea mays L.) N recommendations and bias for N‐rate studies conducted in South Dakota using models created for western Minnesota, I...
Preharvest yield estimates can be used for harvest planning, marketing, and prescribing in‐season fertilizer and pesticide applications. One approach that is being widely tested is the use of machine learning (ML) or artificial intelligence (AI) algorithms to estimate yields. However, one barrier to the adoption of this approach is that ML/AI algor...
Rising sea levels, increasing land use intensification, declining fresh water supplies, and climate variation are accelerating the development of saline and sodic soils worldwide. This chapter defines the issue and discusses the global extent of salt-affected soils. Subsequent chapters are focused on saline/sodic soil economics (Chapter 2), formati...
Our prior study showed that a dormant seeded rye (Secale cereale L.) cover crop
reduced carbon dioxide equivalence (CO2e) in a frigid submesic climate. However, this research did not discuss the impact of the cover crop on temporal changes in soil inorganic nitrogen (N), soil organic carbon (SOC), microbial biomass, and community structure, which...
The slowly establishing salt‐tolerant perennial grasses reduced nitrous oxide (N2O‐N) emissions from saline/sodic soil compared to barren areas. Other salt‐tolerant species may accelerate vegetative establishment and reduce N2O‐N emissions. In a greenhouse study, barley (Hordeum vulgare L.), Florida broadleaf mustard (Brassica juncea L.), and Kernz...
Increasing soil salinity and/or sodicity is an expanding problem in the Northern Great Plains (NGP) of North America. This study investigated the impact of phytoremediation on the soil microbiome and if changes, in turn, had positive or negative effects on plant establishment. Amplicon sequencing and gas chromatograph/mass spectrometer analysis com...
Salt-impacted soils are formed through anthropogenic or natural causes. In the northern Great Plains region of North America, salts that occur in the soil parent materials move upward through the soil profile due to changing land-use and precipitation regimes. If these salts accumulate in the surface soil layer, they impact the ecological integrity...
Because the manual counting of soybean (Glycine max) plants, pods, and seeds/pods is unsuitable for soybean yield predictions, alternative methods are desired. Therefore, the objective was to determine if satellite remote sensing‐based artificial intelligence (AI) models could be used to predict soybean yield. In the study, multiple remote sensing‐...
Plant biostimulants include beneficial fungi and bacteria, and are often applied to foliage to improve crop growth, yield, and/or crop quality. Crop improvements due to biostimulant addition may be modest; therefore, solo applications may not be economical or climate smart. However, biostimulants combined with other postemergence treatments, such a...
Precision agriculture (PA) has been defined as a “management strategy that gathers, processes and analyzes temporal, spatial and individual data and combines it with other information to support management decisions according to estimated variability for improved resource use efficiency, productivity, quality, profitability and sustainability of ag...
By influencing soil organic carbon (SOC), cover crops play a key role in shaping soil health and hence the system's long‐term sustainability. However, the magnitude by which cover crops impacts SOC depends on multiple factors, including soil type, climate, crop rotation, tillage type, cover crop growth, and years under management. To elucidate how...
Canola (Brassica napus L.) may diversify wheat-based cropping systems in the Northern Great Plains. However, agronomic adaptability and stability of high yielding genotypes have not been widely evaluated over the diverse environmental
conditions of South Dakota (SD). A 2-year field experiment was conducted in two contrasting environments (Brookings...
Canola (Brassica napus L.) may diversify wheat‐based cropping systems in the Northern Great Plains. However, agronomic adaptability and stability of high‐yielding genotypes have not been widely evaluated over the diverse environmental conditions of South Dakota (SD). A 2‐year field experiment was conducted in two contrasting environments (Brookings...
Direct competition for resources is generally considered the primary mechanism for weed-induced yield loss. A re-evaluation of physiological evidence suggests weeds initially impact crop growth and development through resource-independent interference. We suggest weed perception by crops induce a shift in crop development, before resources become l...
We examine the interactions, decisions, and evaluations of an interdisciplinary team of researchers tasked with developing an artificial intelligence-based agricultural decision support system that can provide farmers site-specific information about managing nutrients on their land. We answer the following research questions: (1) How does a relatio...
Revegetation of saline–sodic soils is challenging. Over 10 million saline–sodic hectares are intertwined with highly productive soils in the Northern Great Plains, with 3.4 million ha in South Dakota. Establishing salt‐tolerant perennial plants provides soil cover and remediates barren areas. Two perennial salt‐tolerant grass mixes [Mix 1: slender...
Cover crops improve soil health and reduce the risk of soil erosion. However, their impact on the carbon dioxide equivalence (CO2e) is unknown. Therefore, the objective of this 2‐yr study was to quantify the effect of cover crop‐induced differences in soil moisture, temperature, organic C, and microorganisms on CO2e, and to develop machine learning...
Soybean [Glycine max (L.) Merr.] cultivars resistant to synthetic auxin herbicides have provided another mode of action for the postemergence broadleaf weed control. This field study was conducted at three South Dakota locations [Northeast, NERF; east‐central, ARF; and Southeast, SERF) in 2019 and two locations (ARF and SERF) in 2020. The Enlist E3...
Canola (Brassica napus L), biochar and composted manure are potential crop and soil amendments to remediate saline and sonic soils
Several weeds serve as alternative soybean cyst nematode (SCN) hosts. Still, the relative
reproductive capacity of SCN HG types (Heterodera glycines type) on weed hosts relative to soybean is not well understood. This study examined the reproduction of three South Dakota endemic SCN populations—PSCN-1 (HG 0), PSCN-2 (HG 2.5.7), and PSCN-3 (HG 7)—on...
Increased rainfall is increasing the risk of the capillary movement of sodium (Na+)and other salts from buried marine sediments to the soil surface in the North American northern Great Plains. These salts reduce productivity and resilience while increasing theireffect on the environment. Understanding the interactions among management, climate,crop...
Saline/sodic soils are often remediated by applying gypsum, improving drainage, and irrigating with high quality water. However, these management approaches may not be effective or feasible in dryland soils supersaturated with gypsum. A field study, conducted between 2017 and 2021, investigated the effect of phytoremediation on soil and plant healt...
Cover crops provide soil health benefits to crop production. However, adoption is limited in areas with short growing season. We conducted a two-year (2019-2020) field experiment to measure the influence of termination dates of fall seeded rye on early corn growth, gene regulation, and yield. We drilled rye (Secale cereal L.) at 56 kg ha-1 seeding...
Growing food, feed, and fiber in a manner sustainable for future generations is the starting point for improved food security. As the world population continues to grow, it is imperative to improve many aspects of agronomic production systems to better suit local conditions. This special issue of Agronomy Journal examines what agronomists see as to...
Retail dealership survey data suggests that the lack of a qualified precision agriculture (PA) workforce limits the ability of the PA service industry to provide technological knowledge and services to producers who have adopted PA technology. The key empirical findings suggest that retail dealerships have the greatest difficulty finding workers wh...
This literature review focuses on the role of the precision agriculture (PA) custom services industry in facilitating farmer adoption of PA technology. Based on the review, a series of stylized facts are developed that characterize the custom services industry's role in the PA adoption process in the United States. The literature suggests that incr...
Achieving the sustainable development goals of the United Nations requires innovations in agriculture and development of climate‐smart and economically feasible approaches for smallholder farmers in developing countries. Historical climate data of Nepal, which include 116 yr since 1901, has shown an increasing trend for average temperature by 0.016...
Despite differences between the cover crop growth and decomposition phases, few greenhouse gas (GHG) studies have separated these phases from each other. This study's hypothesis was that a living cover crop reduces soil inorganic N concentrations and soil water, thereby reducing N2O emissions. We quantified the effects of a fall‐planted living cere...
Integrated crop-livestock systems (ICLS) can be productive, sustainable, and climate-resilient agricultural systems compared to specialized and intensive systems. This review explores the beneficial traits and contributions of ICLS to food security, social and economic benefits, and resilience, and proposes strategies to adopt ICLSs in low-, medium...
Prior to the 1950s, weeds were controlled by a wide variety of mechanical and cultural methods with limited use of inorganic chemicals at very high rates (100s kg ha–1). With the advent of selective carbon‐based herbicides in the 1950s, herbicide weed management became the norm throughout much of the world, using grams to a few kilograms of active...
Although salinity and sodicity are worldwide problems, information on greenhouse gas (GHG) emissions from agricultural salt‐affected soils is scarce. The CO2–C and N2O–N emissions were quantified from three zones intertwined within a single U.S. northern Great Plains field: a highly productive zone (electrical conductivity with 1:1 soil/water mass...
Weeds occur in patches across landscapes and vary in species, density, time of emergence, and growth rate depending on location. Precision weed management accounts for natural and management-induced variation to optimize inputs (control methodology) to reduce weed presence and improve crop yields across an area. When Anita and I started research on...
Abrasive weeding is a nonchemical weed control tactic that uses small, gritty materials propelled with compressed air to destroy weed seedlings. Organic fertilizers have been used successfully as abrasive grits to control weeds, but the goal for this study was to explore the effects of fertilizer grit, application rates, and background soil fertili...
Cover crops provide soil health benefits to crop production systems. However, adoption is limited in areas with short growing seasons. Fall seeding of rye cover crop may be a better option but more information is needed on termination timing to avoid negative impacts on crop yield. We conducted a two-year (2019-2020) field experiment to determine t...
Cover crops aid in controlling soil erosion, reducing nitrate (NO3) leaching, adding soil organic carbon, and improving soil health. However, cover crops may increase soil greenhouse gas (GHG) emissions during its decomposition. The effects of winter cereal rye (Secale cereal L.) residue on nitrous oxide (N2O) and carbon dioxide (CO2) were quantifi...
Challenges and opportunities in precision weed management
Early spring herbicide applications can have residuals that impede fall‐planted cover crop growth. A greenhouse study examined radish (Raphanus sativus L.) or rye (Secale cereale L.) growth in silty clay loam (southeastern South Dakota) and silt loam (north‐central South Dakota) where corn herbicides had been applied about 120 d prior to collection...
In organic cropping systems, air‐propelled abrasive grits can be used to control in‐row weeds. If the applied abrasive grit is an approved organic fertilizer, these applications may serve a dual purpose of weed control and crop fertility. Laboratory soil incubations examined the N mineralization rates of several grit types with differing C/N ratios...
Transcriptomic responses of plants to weed presence gives insight on the physiological and molecular mechanisms involved in the stress response. This study evaluated transcriptomic and morphological responses of two teosinte (Zea mays ssp parviglumis) (an ancestor of domesticated maize) lines (Ames 21812 and Ames 21789) to weed presence and absence...
The impact of interactions between management and climate on nitrous oxide (N2O), carbon dioxide (CO2), and ammonia (NH3) emissions are not well understood. This study quantified the effect of urea fertilizer application timing on inorganic N movement, immobilization, and the gaseous emissions of N2O‐N, CO2‐C, and NH3‐N. Urea was applied once, at t...
Tamarix spp. (saltcedar) were introduced from Asia to the southern United States as windbreak and ornamental plants and have spread into natural areas. This study determined differential gene expression responses to water deficit (WD) in seedlings of T. chinensis and T. ramosissima from established invasive stands in New Mexico and Montana, respect...
Surface litter protects rangeland soils against wind and water erosion and provides food and nesting materials for wildlife and insects. However, the ability of grassland systems to provide these services depends on the little studied topic of seasonal surface litter decomposition. Seasonal and annual surface litter decomposition rates were determi...
The North American Great Plains tallgrass prairie was once a system of native cool and warm season grasses, which have been degraded by non-native invasive plants. Native grass restoration is highly desirable to improve ecosystem functions and productivity. In this two-year study, the impact of fire, herbicide, and nitrogen on productivity and the...
College students from the Upper Great Plains Region of the United States often come from small towns (pop. <2000), and many have very limited world experience.
Experiential exposure to global perspectives is critical to prepare undergraduates for a better understanding of the world and their future. An International Travel Abroad
China Experience (...
Soybean cyst nematode (SCN) causes over $1.2 billion in revenue loss annually in the USA and consistently ranks as the most threatening pathogen for soybean. SCN weed hosts have been documented in other states in the eastern Corn Belt but very little work has been done in the western Corn Belt. To determine alternative SCN weed hosts in South Dakot...
Control of soil erosion, reduced nitrate (NO3) leaching, adding soil organic carbon and improving soil health are benefits commonly attributed to cover crops. However, cover crops may increase soil greenhouse gas (GHG) emissions. The impact of Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) were quantified from winter cereal rye (Secale...
Cover crops provide benefits to crop production, soil and water quality, and overall soil health. Cover crop adoption is limited due to poor plant establishment, species selection challenges, soil moisture management, and termination timing. The impact of spring planted cover crops on early corn growth and development was quantified using rye (Seca...
Core Ideas
Corn increases the number of differentially expressed genes and the intensity of differential gene expression in response to increasing weed density.
Genes associated with kinase signaling and transport functions are upregulated by weeds.
Genes associated with protein production are downregulated by weeds.
A sugar transporter (PMT5) and...
Weeds are a top management concern among organic vegetable growers. Abrasive weeding is a nonchemical tactic using air-propelled abrasive grit to destroy weed seedlings within crop rows. Many grit types are effective, but if organic fertilizers are used, this could integrate weed and nutrient management in a single field pass. Our objective was to...
Core Ideas
Land use change models may overestimate the importance of commodity prices.
Nebraska grasslands relative to total working lands decreased 1.7% from 2006 to 2014.
South Dakota grasslands relative to total working lands decreased 3% from 2006 to 2014.
In 2012, 84,900 km² of grassland suitable for crops remained as grasslands.
Land stewards...
Core Ideas
Soybean yield loss in South Dakota was dependent on Palmer amaranth density if it emerged before canopy closure.
Soybean yield losses were not Palmer amaranth density dependent when it emerged at the R2 soybean growth stage.
The relative growth rate of Palmer amaranth was rapid and suggests a limited period for effective post‐emergence c...
The success of dicamba-tolerant soybean [ Glycine max (L.) Merr.] has revived concerns about plant growth regulator (PGR) herbicide exposure to conventional soybean. In laboratory studies, soybean root nodulation is inhibited by excess auxin, which is the mechanism of action of PGR herbicides. Soybean exposed to PGRs in a field environment may have...
Core Ideas
Midmorning N2O flux estimates were not consistent with near‐continual data for spring and fall applied urea.
Local N2O sampling protocols must account for temporal changes in management and climatic conditions.
Non‐alignment in soil temperature and N2O patterns in annual‐crop soils is consistent with Fick's Law.
Non‐alignment between tem...
In the Northern Great Plains (NGP), the combined impacts of land-use and climate variability have the potential to place many soils on the tipping point of sustainability. The objectives of this study were to assess if the conversion of grassland to croplands occurred on fragile landscapes in the North America Northern Great Plains. South Dakota an...
Core Ideas
The amount of land impacted by salinity or sodicity is increasing worldwide.
Precision conservation can be used to target corrective treatments to problem areas.
Chemical amendments did not enhance soil health or plant productivity in northern Great Plains soils that did not have effective drainage systems.
The application of chemical am...
Weed control is challenging to farmers who are transitioning from production systems that use synthetic herbicides to organic systems. A 2-year field study examined air-propelled corncob grit abrasion for in-row weed control efficacy and effect on corn yield. Grit was applied based on corn vegetative developmental stages with one (V1, V3 or V5), tw...
Core Ideas
Farmers struggle to maintain and balance economic and environmental sustainability.
Identification of knowledge gaps related to crop residue management.
Discussion of crop residue manage expanded from the U.S. Midwest to a global perspective.
Use of carbon flux tower data to validate simulation models.
Crop residue harvesting impacts soi...
Abrasive grit, applied at high pressure and directed at plant base, can control weeds and increase yield. We evaluated fertilizer [pelletized turkey (Meleagris gallopavo) litter] and non-fertilizer [walnut (Juglans regia) shell] grits for maize and soybean in-row (IR) weed management. Grits were applied at V1 and V5 of maize, and V1 and V3 of soybe...
Weed competition, especially within the crop row, limits the productivity and profitability of organic crop production. Abrasive weeding, a mechanical alternative to hand weeding, uses air-propelled grits to control small weed seedlings growing within the crop row. Recent research has demonstrated the successful use of abrasive weeding to reduce we...