Browsing by Author "Carr, Patrick M."

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Changes in Biological Soil Health Properties in Response to Increased Crop Diversity in a Dryland Wheat-Based Cropping System
(Informa UK Limited, 2024-08) Eberly, Jed O.; Hammontree, Jenni W.; Fordyce, Simion I.; Jones, Clain A.; Carr, Patrick M.
Diversifying wheat (Triticum aestivum L.)-based cropping systems is important for the sustainability of dryland agriculture. Research has focused on the agronomic benefits of increased crop diversity in semi-arid environments, but less is known about the impacts of increased crop diversity on the soil microbial community. This work compared soil health parameters between a continuous wheat crop sequence to a diverse sequence that included pea (Pisum sativum L.), proso millet (Panicum miliaceum L.), safflower (Carthamus tinctorius, L.), and spring wheat. Respiration was higher (p < .005) in the diverse sequence while activity of N-acetyl-β-d-glucosaminidase was lower (p < .05) with a mean rate of 26.3 and 16.3 mg ρ-nitrophenol kg−1 soil h−1 for the continuous wheat and diverse sequences, respectively. The mean net nitrogen mineralized during the growing season was 33.2 ± 2.5 kg ha−1 and was not different between treatments (p > .05). No difference was observed in bacterial alpha diversity, while fungal community diversity was 52% lower in the diverse rotation. The results of this work suggest that specific crops in a rotation may impact microbial processes related to nitrogen mineralization and that the soil fungal community may be more sensitive to changes in crop sequence than the soil bacterial community.
Compositional profiling of the rhizosphere microbiome of Canada thistle reveals consistent patterns across the United States northern Great Plains
(Springer Science and Business Media LLC, 2024) Eberly, Jed O.; Hurd, Asa; Oli, Dipiza; Dyer, Alan T.; Seipel, Tim F.; Carr, Patrick M.
Canada thistle is a pervasive perennial weed, causing challenges to agricultural and natural ecosystems globally. Although research has focused on the phenology, genetics, and control of Canada thistle, little is known about the rhizosphere microbiome and the role plant–microbe interactions play in invasion success. This study investigated the rhizosphere microbiome of Canada thistle across diverse climates, soils, and crops in the U.S. northern Great Plains. Soil and rhizosphere samples were collected and bacterial 16S and fungal ITS2 sequencing were performed to characterize the core microbiome and identify potential factors contributing to invasion success. Amplicon sequencing revealed a stable core microbiome that was detected in the Canada thistle rhizosphere across all locations. The core microbiome was dominated by the bacterial phyla Actinobacteriota and Proteobacteria and fungal phyla Ascomycota and Basidiomycota. Differential abundance analysis showed rhizosphere fungal communities were enriched in pathogen-containing genera with a 1.7-fold greater abundance of Fusaria and a 2.6-fold greater abundance of Gibberella compared to bulk soil. Predictive functional profiling showed rhizosphere communities were enriched (p < 0.05, FDR corrected) in plant pathogen fungal guilds which represented 19% of the fungal community. The rhizosphere microbiome was similar in composition across environments, highlighting the stable association between Canada thistle and specific microbial taxa. This study characterized the core microbiome of Canada thistle, and the findings highlight plant–microbe interactions shaping invasive behavior. These findings are important for understanding the ecological impacts of plant invasion and soil-microbe ecological processes.
Compositional profiling of the rhizosphere microbiome of Canada thistle reveals consistent patterns across the United States northern Great Plains
(Springer Science and Business Media LLC, 2024-08) Eberly, Jed O.; Hurd, Asa; Oli, Dipiza; Dyer, Alan T.; Seipel, Tim F.; Carr, Patrick M.
Canada thistle is a pervasive perennial weed, causing challenges to agricultural and natural ecosystems globally. Although research has focused on the phenology, genetics, and control of Canada thistle, little is known about the rhizosphere microbiome and the role plant–microbe interactions play in invasion success. This study investigated the rhizosphere microbiome of Canada thistle across diverse climates, soils, and crops in the U.S. northern Great Plains. Soil and rhizosphere samples were collected and bacterial 16S and fungal ITS2 sequencing were performed to characterize the core microbiome and identify potential factors contributing to invasion success. Amplicon sequencing revealed a stable core microbiome that was detected in the Canada thistle rhizosphere across all locations. The core microbiome was dominated by the bacterial phyla Actinobacteriota and Proteobacteria and fungal phyla Ascomycota and Basidiomycota. Differential abundance analysis showed rhizosphere fungal communities were enriched in pathogen-containing genera with a 1.7-fold greater abundance of Fusaria and a 2.6-fold greater abundance of Gibberella compared to bulk soil. Predictive functional profiling showed rhizosphere communities were enriched (p < 0.05, FDR corrected) in plant pathogen fungal guilds which represented 19% of the fungal community. The rhizosphere microbiome was similar in composition across environments, highlighting the stable association between Canada thistle and specific microbial taxa. This study characterized the core microbiome of Canada thistle, and the findings highlight plant–microbe interactions shaping invasive behavior. These findings are important for understanding the ecological impacts of plant invasion and soil-microbe ecological processes.
Cool semi-arid cropping treatments alter Avena fatua's performance and competitive intensity
(Wiley, 2024-03) Larson, Christian D.; Wong, Mei Long; Carr, Patrick M.; Seipel, Timothy
Introduction. Multiple herbicide-resistant Avena fatua L. is common in the Northern Great Plains, USA. This prevalence and the ecological impacts of tillage in this semi-arid agricultural region have created a need for integrated weed management, with a specific knowledge gap in using annual forage crops and targeted grazing for A. fatua suppression. Materials and Methods. A 2-year study in central Montana, USA, assessed A. fatua performance (aboveground biomass, stem density and seed production) in response to seven cropping treatments: (1–4) tall and short spring wheat cultivars crossed with high and low seeding rates, (5–6) annual forage mixture terminated using sheep grazing and simulated haying and (7) tilled fallow. Avena fatua's competitive intensity in wheat and the annual forage mixture was determined using a relative competition intensity index. Results. Avena fatua performance was lowest in tilled fallow, although stem density and seed production did not differ from the grazed annual forage treatment. Response variables were lower in the forage treatments compared with the wheat treatments, and there were no differences among the four fully crossed wheat treatments. Separate analysis of the wheat treatments indicated lower A. fatua biomass and stem density when wheat was sown at a higher rate with no impact of wheat height. Avena fatua competition impacted wheat and forage crops but was more intense for wheat. Conclusion. Tillage was the most effective treatment at reducing A. fatua performance, but annual forage mixtures can be used to resist A. fatua invasion (reduced A. fatua competitive intensity) and limit its performance after invasion. We conclude that crop sequences that combine higher cash crop (wheat) seeding rates and competitive annual forage mixtures may be utilized to manage A. fatua invaded systems, thereby reducing heavy reliance on tillage in the US Northern Great Plains and similar semi-arid regions.
Cover crops to improve soil health in the North American Great Plains
(Wiley, 2021-09) Obour, Augustine K.; Simon, Logan M.; Holman, Johnathon D.; Carr, Patrick M.; Schipanski, Meagan; Fonte, Steven; Ghimire, Rajan; Nleya, Thandiwe; Blanco‐Canqui, Humberto
Rotating cereal crops (e.g., wheat [Triticum aestivum L.] with a 10- to 21-mo summer fallow period [fallow]) is a common farming practice in dryland (rainfed) agricultural regions. Fallow is associated with several challenges including low precipitation storage efficiency, depletion of soil organic carbon (SOC), loss of soil fertility, little crop residue retention and soil erosion, and few control options for herbicide-resistant (HR) weeds. The inability to effectively control HR weeds poses a major challenge to maintaining soil and water conservation practices such as no-tillage, as some producers are considering tillage to control weeds. Cover crop (CC) integration into wheat-based production systems to replace portions of the fallow period provides an opportunity to increase SOC, improve soil fertility, suppress weeds, and increase profitability of dryland crop production, especially when CCs are used as forage. This forum paper used the North American Great Plains as a model region to review information on (a) challenges of dryland agriculture; (b) integrating CCs in dryland agriculture; (c) benefits, challenges, and limitations of CCs in dryland crop production; (d) management options for CC integration in dryland grain systems; and (e) recommendations for future research efforts.
Evaluating the impact of Rht hypomorphic mutations in durum wheat
(Wiley, 2021-12) Brown, McKenna M.; Martin, John M.; Jobson, Emma M.; Hogg, Andrew C.; Carr, Patrick M.; Giroux, Michael J.
Increasing the yield of wheat (Triticum spp.) requires identifying new allelic combinations by crossing or by creating useful variation in yield limiting genes. Wheat yield is impacted by many factors, including tiller number and seeds per tiller, both of which are impacted by the Reduced height (Rht) gene. Durum wheat [T. turgidum L. subsp. durum (Desf.) van Slageren] varieties are either standard height, wild type for Rht (Rht-B1a), or are semidwarf and carry the Rht-B1b allele. Rht-B1b increases productive tillers but can result in plants too short for easy harvest in the northern United States and shorter coleoptiles that reduce dry soil germination. In this study, durum plants varying for Rht alleles created by ethyl methanesulfonate (EMS) mutagenesis were studied to determine the impact of each allele upon agronomic and seed traits. The projects’ goal is to increase durum wheat yield through the development of a plant with height intermediate between current full-height and semidwarf varieties. Experiments included field trials, coleoptile length and gibberellic acid (GA) responsiveness assays, and an in vitro test to determine the impact of each Rht mutation upon binding to Gibberellin Insensitive Dwarf1 (GID1). It was found that the Rht-B1b-E529K allele conferred plant height and coleoptile length intermediate between Rht-B1b and Rht-B1a containing plants, while two Rht-A1 alleles had lesser impacts with trends toward intermediate-height plants. The results of this research demonstrate that hypomorphic Rht alleles that alter Rht binding to GID1 may prove useful in optimizing durum wheat height to increase yield across different growing conditions.
Evaluation of environment and cultivar impact on lentil protein, starch, mineral nutrients, and yield
(Wiley, 2021-12) Chen, Chengci; Etemadi, Fatemeh; Franck, William; Franck, Sooyoung; Abdelhamid, Magdi T.; Ahmadi, Jafar; Mohammed, Yesuf Assen; Lamb, Peggy F.; Miller, John H.; Carr, Patrick M.; McPhee, Kevin; Zhou, Yi; Torabian, Shahram; Qin, Ruijun
Lentil (Lens culinaris Medik.) is an important source of protein, starch, and mineral nutrients in many parts of the world. However, the impact of environment and cultivar on the enrichment of these nutrients is not well understood. Four lentil cultivars (‘Avondale’, ‘CDC Richlea’, ‘CDC Maxim’, and ‘CDC Imvincible’) varying in color, seed size, and maturity were evaluated at five Montana locations with diverse climatic and soil conditions over 3 yr. Significant cultivar, location, and year effects were found for yield, protein, starch, and minerals. Grain protein concentration was the highest at Moccasin (262 g kg−1) and lowest at Richland (246 g kg−1), whereas starch concentration was the highest at Richland (455 g kg−1) and lowest at Moccasin(441gkg−1). Among cultivars, Avondale was the top yielding cultivar (1965 kg ha−1)and adaptable to most of the environments; CDC Imvincible was the top protein producer (265 g kg−1); and CDC Richlea is the leading starch producer (456 g kg−1). Grain protein concentration was negatively correlated with starch. Lentil grains varied in nutrient concentrations across locations, with the north central Montana region producing 10- to 20-times greater selenium concentration than other locations. CDC Maxim had the highest iron (62.1 mg kg−1) and zinc (31.5 mg kg−1) concentrations.Seed protein concentration was positively correlated with phosphorus, sulfur, cop-per, and boron. Seed starch is positively correlated with magnesium and manganese.Results suggest that plant breeding and production site selection could enrich lentil nutrient concentrations to help combat malnutrition in the world.
Sentinel-2-based predictions of soil depth to inform water and nutrient retention strategies in dryland wheat
(Elsevier BV, 2023-11) Fordyce, Simon I.; Carr, Patrick M.; Jones, Clain; Eberly, Jed O.; Sigler, W. Adam; Ewing, Stephanie; Powell, Scott L.
The thickness or depth of fine-textured soil (zf) dominates water storage capacity and exerts a control on nutrient leaching in semi-arid agroecosystems. At small pixel sizes (< 1 m; ‘fine resolution’), the normalized difference vegetation index (NDVI) of cereal crops during senescence (Zadoks Growth Stages [ZGS] 90–93) offers a promising alternative to destructive sampling of zf using soil pits. However, it is unclear whether correlations between zf and NDVI exist (a) at larger pixel sizes (1–10 m; ‘intermediate resolution’) and (b) across field boundaries. The relationship of zf to NDVI of wheat (Triticum aestivum L.) was tested using images from a combination of multispectral sensors and fields in central Montana. NDVI was derived for one field using sensors of fine and intermediate spatial resolution and for three fields using intermediate resolution sensors only. Among images acquired during crop senescence, zf was correlated with NDVI (p < 0.05) independent of sensor (p = 0.22) and field (p = 0.94). The zf relationship to NDVI was highly dependent on acquisition day (p < 0.05), but only when pre-senescence (ZGS ≤ 89) images were included in the analysis. Results indicate that cereal crop NDVI of intermediate resolution can be used to characterize zf across field boundaries if image acquisition occurs during crop senescence. Based on these findings, an empirical index was derived from multi-temporal Sentinel-2 imagery to estimate zf on fields in and beyond the study area.
Tillage and crop sequences for organic Cirsium arvense management in the Northern Great Plains
(Wiley, 2024-06) Larson, Christian D.; Hettinger, Kara; Carr, Patrick M.; Miller, Perry R.; Volkman, McKenna; Chichinsky, Daniel; Seipel, Tim
The perennial rhizomatous weed Cirsium arvense (L.) Scop. is difficult to manage on semiarid organic farms. Our objective was to quantify the impact of eight 4-year crop sequences crossed with standard- and reduced-tillage on C. arvense occurrence (presence/absence), stem density, and aboveground biomass at two semiarid sites in Montana. The sequences represented a range of crop competition from high (multiple years of perennial forage [alfalfa, Medicago sativa L.]) to low (2 years of continuous fallow), with intermediate sequences consisting of different annual species. Final-year spring wheat (Triticum aestivum L. emend. Thell.) was planted in all sequences to determine impacts on subsequent cash crop production. Through time, alfalfa and double fallow sequences reduced C. arvense density and biomass where it was established, although its invasion into new areas increased in the double fallow. Final-year C. arvense occurrence and stem density were lower in the alfalfa sequence compared with six and four annual crop sequences, respectively (p < 0.05). Final year C. arvense biomass was higher at one site than the other, although not in the double fallow sequence. Wheat grain yields differed in response to crop sequences at the two sites: at one site, grain yield was lowest in the alfalfa sequence, especially when standard-tillage was used, while yields were highest in the alfalfa and double fallow sequences at the other site. Using perennial forages in semiarid organic systems can be effective for managing C. arvense, but subsequent cash crop yield may be depressed.
Warm-Season Forage Options in Northern Dryland Regions
(2020-06) Carr, Patrick M.; Boss, Darrin L.; Chen, Chengci; Dafoe, Julia M.; Eberly, Jed O.; Fordyce, Simon; Hydner, Roger M.; Fryer, Heather K.; Lachowiec, Jennifer A.; Lamb, Peggy F.; McVay, Kent A.; Khan, Qasim A.; Miller, Perry R.; Miller, Zachariah J.; Torrion, Jessica A.
Rotating summer fallow with wheat (Triticum spp.) is done in dryland grain farming at upper latitudes to stabilize yields over time and to prevent crop failure. However, summer fallow is costly since weeds must be controlled and crops are not grown. Replacing summer fallow with grain crops can generate low economic returns. Previous research indicated that annual cool‐season forages can be substituted for summer fallow in dryland cropping systems. Our objective was to determine if annual warm‐season species were suited for forage production in monocultures and polycultures in the U.S. northern Great Plains. Dry matter (DM) production by 20 warm‐ and cool‐season crop monocultures and 4 polycultures was determined across six environments during 2016, and by 25 warm‐ and cool‐season crop monocultures and polycultures across four environments from 2016 through 2018. Maize (Zea mays L.) monoculture produced forage DM in amounts equal to, or greater than, those produced by other warm‐ and cool‐season crop treatments (P < 0.05). Maize DM production averaged 2.5 to 5.7 Mg ha−1, depending on the study and environment. Sorghum (Sorghum bicolor L.), foxtail millet [Setaria italica (L.) P. Beauv.] and sunflower (Helianthus annuus L.) also produced relatively large amounts of forage DM. Polycultures failed to produce more DM than monocultures consistently (P > 0.40). These results indicate that maize and other warm‐season crops are adapted for dryland forage production in cool regions at upper latitudes. Additional research is needed to determine the impacts of annual warm‐season forages on grain yield in a forage‐wheat crop sequence.