Data from: Barley cover crops outperform brown mustard for early-season weed control in New Mexico chile pepper
Data files
Jan 14, 2026 version files 541.61 KB
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AMAPA_seed_germination_data_description.pdf
57.63 KB
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AMAPA_seed_germination_data.xlsx
50.66 KB
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AMAPA_seed_vaibility_data_description.pdf
57.23 KB
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AMAPA_seed_viability_data.xlsx
20.43 KB
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AMAPA_seedling_development_data_description.pdf
56.42 KB
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AMAPA_seedling_development_data.xlsx
10.97 KB
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Cover_crop_biomass_data_description.pdf
43.49 KB
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Cover_crop_biomass_data.xlsx
22.02 KB
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Fruit_yield_data_description.pdf
44.83 KB
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Fruit_yield_data.xlsx
13.28 KB
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Hand_hoeing_data_description.pdf
49.19 KB
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Hand_hoeing_data.xlsx
16.97 KB
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README.md
14.54 KB
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Weed_density_data_description.pdf
47.36 KB
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Weed_density_data.xlsx
36.62 KB
Abstract
Barley (Hordeum vulgare L.) and brown mustard [Brassica juncea (L.) Czern.] are winter cover crops known to produce allelochemicals that suppress plant growth. Incorporating barley or brown mustard residues into the soil before planting a spring-seeded cash crop may suppress early-season weeds in the cash crop; however, the comparative levels of weed suppression offered by barley and brown mustard cover crops incorporated into soil have not been determined. This study analyzed the relative capacities of barley and brown mustard cover crops to suppress early-season weeds of spring-seeded chile pepper (Capsicum annuum L.). Reductions in weed density or hand-hoeing time as a result of barley and/or brown mustard cover crop treatment were determined in two chile pepper fields in New Mexico over two growing seasons. For cover crop species that suppressed weeds in multiple site-years, a controlled environment study clarified possible growth stages adversely affected by determining the effects of cover crop–amended soil on the germination and seedling development of Palmer amaranth (Amaranthus palmeri S. Watson). Field study results indicated barley reduced early-season weed densities of chile pepper by up to 80 % compared with the noncover control. Barley also reduced hoeing time in 3 of 4 site-years without affecting chile pepper fruit yield. Mustard cover crops reduced weed density in only 1 site-year (56 % reduction relative to noncover control) and did not decrease hoeing time. The controlled environment study indicated that soil amended with barley slowed germination of A. palmeri without inhibiting seedling development. The results of this study indicate that a barley cover crop is more effective than brown mustard for early-season weed control of chile pepper in the southwestern United States.
Dataset DOI: 10.5061/dryad.vdncjsz8v
Description of the data and file structure
The first objective of this study was to quantify amounts of aboveground biomass produced by barley (Hordeum vulgare) and brown mustard (Brassica juncea) cover crops grown in southern and central New Mexico. The second objective of this study was to evaluate barley and brown mustard green manures for their effects on weed density, hand-hoeing time, and fruit yield in chile pepper (Capsicum annuum) seeded after termination of the cover crops. The third objective was to determine barley-amended soil effects on germination and seedling development of the annual weed, Palmer amaranth (Amaranthus palmeri).
To accomplish Objective 1 and Objective 2, a field study was conducted at two sites, with each site including two experimental runs. Treatments were arranged in a randomized complete block design with four replications. Treatments consisted of barley monocultures, mustard monocultures, a barley-mustard combination, and a no cover crop control. For each site-year, cover crops were seeded in fall and terminated in spring, when chile pepper was subsequently seeded. One day before cover crop termination, aboveground cover crop biomass was collected, dried and weighed. Cover crops were terminated by mowing. Within 30 to 60 minutes of mowing, residues were incorporated into the soil to a depth of 15 cm using an offset tandem disc. Then, a lister was used to create raised beds approximately 25 cm high and 76 cm wide. Plots were subsequently furrow-irrigated to saturate upper soil levels. Three weeks after cover crop termination, beds were disked and shaped using a bed shaper, approximately 15 % of aboveground cover crop residue remained on the soil surface.
Chile pepper was seeded using mechanical seeders. Beginning 3 weeks after sowing chile pepper, weed densities were determined every 2 weeks for 6 weeks. At each observation time, weeds within two permanently established 0.25 m2 quadrats in each plot were identified to the species level, counted, and removed. Coincident with the second weed-counting event, the time required to hand hoe a permanently established 8-m transect within each plot was recorded. At the end of the growing season, all marketable green fruits were hand harvested along an 8-m transect in each plot. Fresh weights of marketable fruits were determined in the field and scaled to kg ha -1.
To accomplish Objective 3, soil was collected from each barley and noncover control plot after mowing and incorporation of cover crops, but prior to irrigation. For each site-year, soil samples were aggregated within a treatment and homogenized. The effects of barley-amended soil on Palmer amaranth germination were determined with a three-step process. First, seeds were incubated in soil collected from barley or noncover control plots. Next, seeds were removed from soil and subjected to germination assays. Finally, time-integrated measures of seed germination were determined and compared between the treatments. Barley-amended soil was also examined for suppression of Palmer amaranth seedling development. This was accomplished by growing Palmer amaranth seedlings in barley-amended soil for 28 days and then comparing plant heights and growth stages against Palmer amaranth plants grown in soil without barley residues.
Files and variables
File: AMAPA_seed_germination_data.xlsx
Description: Spreadsheet contains data for Palmer amaranth (Amaranthus palmeri, AMAPA) seed germination following seed incubation in soil collected from two sites following termination of different cover crop treatments.
Variables:
- Year: Year in which field soil was collected
- Run: Experimental run, with “1” indicating experimental run one and “2” indicating experimental run two. Experimental runs correspond to years in which field soil was collected.
- Date: Day on which germination data were collected
- Time: Time of day in which germination data were collected
- Species: Plant species in study
- Location: Where cover crops were grown and soil collected following cover crop termination. “Leyendecker” indicates the New Mexico State University Leyendecker Plant Science Research Center. “Los Lunas” indicates the New Mexico State University Agricultural Science Center at Los Lunas.
- Treatment: Cover crop treatment, with “Barley” indicating the barley monoculture, and “Noncover ”indicating the no cover crop control
- Rep: Experimental replicate
- Germinants: Number of seeds that completed germination as indicated by radicle protrusion through seed coat.
File: AMAPA_seed_germination_data_description.pdf
Description: Companion PDF file for AMAPA_seed_germination_data.xlsx describing the content of each column.
File: AMAPA_seed_viability_data.xlsx
Description: Spreadsheet contains data for Palmer amaranth (Amaranthus palmeri, AMAPA) seed viability following assays that assessed germinability after incubation in soil from different cover crop treatments. Cover crops were grown in two sites, two years per site. Soil was collected following termination of the cover crops.
Variables:
- Year: Year in which field soil was collected
- Run: Experimental run, with “1” indicating experimental run one and “2” indicating experimental run two. Experimental runs correspond to years in which field soil was collected.
- Species: Plant species in study
- Location: Where cover crops were grown and soil collected following cover crop termination. “Leyendecker” indicates the New Mexico State University Leyendecker Plant Science Research Center. “Los Lunas” indicates the New Mexico State University Agricultural Science Center at Los Lunas.
- Treatment: Cover crop treatment, with “Barley” indicating the barley monoculture, and “Noncover ”indicating the no cover crop control
- Rep: Experimental replicate
- Nongerminated_Total: Number of seeds that did not complete germination in the assay, with completion of germination indicated by radicle protrusion.
- Nongerminated_Viable: Number of nongerminated seeds that were viable, with viability determined from resistance to applied pressure
- Nongerminated_Nonviable: Number of nongerminated seeds that were not viable. Nonviable seeds collapsed under light pressure applied to seed coat.
File: AMAPA_seed_vaibility_data_description.pdf
Description: Companion PDF file for AMAPA_seed_viability_data.xlsx describing the content of each column.
File: AMAPA_seedling_development_data.xlsx
Description: Spreadsheet contains data for the development of Palmer amaranth (Amaranthus palmeri, AMAPA) seedlings grown in soil collected from two sites following termination of different cover crop treatments.
Variables:
- Year: Year in which field soil was collected
- Run: Experimental run, with “1” indicating experimental run one and “2” indicating experimental run two. Experimental runs correspond to years in which field soil was collected.
- Rep: Experimental replicate
- Location: Where cover crops were grown and soil collected following cover crop termination. “Leyendecker” indicates the New Mexico State University Leyendecker Plant Science Research Center. “Los Lunas” indicates the New Mexico State University Agricultural Science Center at Los Lunas.
- Treatment: Cover crop treatment, with “Barley” indicating the barley monoculture, and “Noncover ”indicating the no cover crop control
- Species: Plant species in study
- Survived: Plant survival through the study period. “Y” indicates plant survival, and “N” indicates the plant did not survive to end of the study period. Seedling growth assays were twenty eight days in duration.
- Leaf: Number of leaves on an individual plant at the conclusion of the study period.
- Height: Plant height in centimeters at the conclusion of the study period.
File: AMAPA_seedling_development_data_description.pdf
Description: Companion PDF file for AMAPA_seedling_development_data.xlsx describing the content of each column.
File: Cover_crop_biomass_data.xlsx
Description: Spreadsheet contains end-of-season dry weights for mustard and barley cover crops grown at two sites in New Mexico, U.S.A. in fall 2021 to spring 2022 and fall 2022 to spring 2023.
Variables:
- Location: Where the cover crops were grown, with “Leyendecker” indicating the New Mexico State University Leyendecker Plant Science Research Center, and “Los Lunas” indicating the New Mexico State University Agricultural Science Center at Los Lunas.
- Year: Year in which cover crop biomass were collected.
- Plot_ID: Plot identification #
- Rep: Experimental replicate
- Treatment: Cover crop treatment, with “Mustard” indicating the mustard monoculture, “Barley” indicating the barley monoculture, “Combo” indicating the mustard-barley combination, and “Noncover ”indicating the no cover crop control
- Species: The plant species that was measured, with “Mustard” indicating the brown mustard (Barassica juncea) cultivar ‘Caliente Rojo’, “Barley” indicating the barley (Hordeum vulgare) cultivar ‘Stockford’, and “Noncover ”indicating the no cover crop control.
- Weight: Dry aboveground biomass in units of gram per 0.25 m2
File: Cover_crop_biomass_data_description.pdf
Description: Companion PDF file for Cover_crop_biomass_data.xlsx describing the content of each column.
File: Fruit_yield_data.xlsx
Description: Spreadsheet contains fruit yield data for chile pepper grown following different cover crop treatments at two sites in New Mexico, U.S.A. in summer 2022 and summer 2023.
Variables:
- Year: Year in which fruit yield data were collected.
- Date: Day of year on which fruit yield data were collected
- Location: Where the chile pepper was grown, with “Leyendecker” indicating the New Mexico State University Leyendecker Plant Science Research Center, and “Los Lunas” indicating the New Mexico State University Agricultural Science Center at Los Lunas.
- Plot: Plot identification #
- Rep: Experimental replicate
- Treatment: Cover crop treatment, with “Mustard” indicating the mustard monoculture, “Barley” indicating the barley monoculture, “Combo” indicating the mustard-barley combination, and “Noncover ”indicating the no cover crop control
- Kg_Per_8m: Fresh weight of chile pepper fruits from 8-m of crop row
- Kg_Per_Ha: Fresh weights of chile pepper fruits from experimental plots, scaled to one hectare
File: Fruit_yield_data_description.pdf
Description: Companion PDF file for Fruit_yield_data.xlsx describing the content of each column.
File: Hand_hoeing_data.xlsx
Description: Spreadsheet contains hand hoeing data for chile pepper grown following different cover crop treatments at two sites in New Mexico, U.S.A. in summer 2022 and summer 2023.
Variables:
- Year: Year in which hand hoeing data were collected.
- Hoeing: Sequential hoeing events. Hoeing Event 1 took place 48, 36, 26, and 35 days after chile pepper seeding (DAS) for Leyendecker 2022, Leyendecker 2023, Los Lunas 2022, and Los Lunas 2023, respectively. Hoeing Event 2 took place 60, 50, 40, and 49 DAS for Leyendecker 2022, Leyendecker 2023, Los Lunas 2022, and Los Lunas 2023, respectively. Hoeing Event 3 occurred 74, 64, 63, and 61 DAS for Leyendecker 2022, Leyendecker 2023, Los Lunas 2022, and Los Lunas 2023, respectively.
- Location: Where the chile pepper was grown, with “Leyendecker” indicating the New Mexico State University Leyendecker Plant Science Research Center, and “Los Lunas” indicating the New Mexico State University Agricultural Science Center at Los Lunas.
- Rep: Experimental replicate
- Treatment: Cover crop treatment, with “Mustard” indicating the mustard monoculture, “Barley” indicating the barley monoculture, “Combo” indicating the mustard-barley combination, and “Noncover ”indicating the no cover crop control
- Plot_ID: Plot identification #
- Minutes: Number of minutes required for one individual to hand hoe an eight meter transect within the plot
File: Hand_hoeing_data_description.pdf
Description: Companion PDF file for Hand_hoeing_data.xlsx describing the content of each column.
File: Weed_density_data.xlsx
Description: Spreadsheet contains weed density data for chile pepper grown following different cover crop treatments at two sites in New Mexico, U.S.A. in summer 2022 and summer 2023.
Variables:
- Year: Year in which weed density data were collected
- Date: Day on which weed density data were collected
- Location: Where the chile pepper was grown, with “Leyendecker” indicating the New Mexico State University Leyendecker Plant Science Research Center, and “Los Lunas” indicating the New Mexico State University Agricultural Science Center at Los Lunas.
- Rep: Experimental replicate
- Plot_ID: Plot identification #
- Treatment: Cover crop treatment, with “Mustard” indicating the mustard monoculture, “Barley” indicating the barley monoculture, “Combo” indicating the mustard-barley combination, and “Noncover ”indicating the no cover crop control
- Subplot: Subplot from which weed density data were collected
- Monocots: Number of monocot weeds per 0.25 m2
- Dicots: Number of dicot weeds per 0.25 m2
- Total: Total number of weeds per 0.25 m2
- Plot_monocots: Number of monocot weeds combined across subplots, resulting in the number of monocot weeds per 0.5 m2
- Plot_dicots: Number of dicot weeds combined across subplots, resulting in the number of dicot weeds per 0.5 m2
- Plot_total: Total number of weeds combined across subplots, resulting in the total number of weeds per 0.5 m2
File: Weed_density_data_description.pdf
Description: Companion PDF file for Weed_density_data.xlsx describing the content of each column.