Data and code from: Sowing date and seeding rate influence cereal rye productivity across the Northeastern United States
Data files
Apr 15, 2026 version files 61.05 KB
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README.md
8.09 KB
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RYE_SRxPD_DataCode.zip
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Abstract
Improving the management of cereal rye (Secale cereale L.), the most frequently used cover crop in the United States, provides an opportunity to enhance agroecosystem service provisioning. Services such as erosion control, weed suppression, and nitrate leaching mitigation are correlated with cereal rye ground cover and biomass, which decline as sowing dates are delayed. Our objective was to quantify whether increasing cereal rye seeding rates could compensate for lost growing degree days as sowing is delayed across the Northeastern United States, and if early spring ground cover could predict late spring biomass and guide grower decision making. We established a two-factor experiment across 13 site-years to test the effects of sowing date, relative to the historic first frost date of each location, and seeding rate (0, 17, 34, 67, 101, and 135 kg ha−1) on cereal rye productivity and weed suppression. Delaying sowing from 2 weeks before to 2 weeks after the historic first frost date decreased cereal rye ground cover by 57%, biomass by 44%. Increasing seeding rates could not fully compensate for fewer growing degree days. Increasing seeding rates up to 60 kg ha−1 maximized ground cover, biomass, and weed suppression at most site-years. Ground cover in early spring was correlated with biomass at anthesis, independent of sowing date, indicating utility as a decision support tool for growers. Overall, our results suggest that seeding rates up to 60 kg ha−1, which is lower than that existing regional recommendations, balance seed costs with ecosystem service provisioning potential in the Northeastern United States.
Dataset DOI: 10.5061/dryad.zkh1893rm
Description of the data and file structure
Data were collected to assess cereal rye productivity in response to seeding rate (n=6) and sowing date (n=3). Data were collected from field trials at 13 site-years across the Northeastern US.
Data collection included cereal rye stand counts (plants/m2) conducted 3 weeks after sowing, ground cover (fractional green canopy cover; %) using smartphone images and the Canopeo app, cereal rye biomass at mid-anthesis (kg/ha), and weed biomass in cereal rye at mid-anthesis (kg/ha).
Soil data (nitrate-N, P, pH, organic matter) were collected at each sowing date at each site-year.
Growing degree days (GDDs) were calculated using the Baskerville and Emin sine method (base temperature 4.4C) between sowing and mid-anthesis, when biomass was harvested.
Files and variables
The folder RYE_SRxPD_DataCode.zip contains the following files:
File: RYE_SRxPD_Data.csv
Description: Main data file. 'na' indicates cells in site-years where data were not collected.
Variables
- site: location identifier (BARC=Beltsville Agricultural Research Center; CT=Connecticut; DE=Delaware; MA=Massachusetts; NY=New York; PA=Pennsylvania; UMD=University of Maryland Wye Research & Education Center; VT=Vermont)
- year: indicates year in which biomass was harvested. 2022 indicates experiment was initiated fall 2021 and harvested spring 2022; 2023 indicates experiment was initiated fall 2022 and harvested spring 2023.
- block: replicate number
- plot: plot number
- pd: calendar date of cereal rye sowing
- pd_fac: relative date of cereal rye sowing (1 = early, 2 = middle, 3 = late)
- rye_kg_adj_to_row_spacing: dry cereal rye biomass in kg/ha that has been scaled up from the 0.25m2 sample size to field-scale based on the grain drill spacing used at each site.
- weed_kg: dry weed biomass in kg/ha
- seedlings_exp_per_quad: number of expected seedlings per quadat. Calculated based on seeding rate and seed weight of cereal rye for each year.
- rate_lbs: cereal rye seeding rate in lbs/ac
- seedling_n: counts of cereal rye seedlings in 0.25m2
- canopy_cover: fractional green canopy cover (%)
- GDD_anthesis: growing degree days (base 4.4C) calculated from sowing to harvest
- soil_n: soil nitrate at sowing (cadmium reduction method)
- soil_pH: soil pH at sowing (water method)
- soil_p: soil phosphorus at sowing (melich-3 method)
- soil_OM: soil organic matter at sowing (loss on ignition)
File: RYE_SRxPD_ModelCoefs.csv
Description: Cereal rye biomass model coefficients extracted from non-linear asymptotic regression models of cereal rye biomass in response to sowing date and seeding rate by site-year. 'na' indicates cells in site-years where data were not collected.
Variables
- year: indicates year in which biomass was harvested. 2022 indicates experiment was initiated fall 2021 and harvested spring 2022; 2023 indicates experiment was initiated fall 2022 and harvested spring 2023.
- site: location identifier (BARC=Beltsville Agricultural Research Center; CT=Connecticut; DE=Delaware; MA=Massachusetts; NY=New York; PA=Pennsylvania; UMD=University of Maryland Wye Research & Education Center; VT=Vermont)
- pd: relative date of cereal rye sowing (1 = early, 2 = middle, 3 = late)
- d: upper limit (maximum biomass)
- se.d: standard error of d
- e: steepness of increase as seeding rate increases
- se.e: standard error of e
- ed90: seeding rate necessary to reach 90% of the maximum biomass
- se: standard error of ed90
- rmse: root mean square error
File: RYE_SRxPD_Precip.csv
Description: Daily precipitation data used to create Figure S1.
Variables
- site: location identifier (BARC=Beltsville Agricultural Research Center; CT=Connecticut; DE=Delaware; MA=Massachusetts; NY=New York; PA=Pennsylvania; UMD=University of Maryland Wye Research & Education Center; VT=Vermont)
- year: indicates year in which biomass was harvested. 2022 indicates experiment was initiated fall 2021 and harvested spring 2022; 2023 indicates experiment was initiated fall 2022 and harvested spring 2023.
- date: calendar data
- SD: y (yes)/ n (no) determining if associated calendar date is a sowing date for a given site-year. y indicates that the date is a sowing date.
- SD_rel: 'na', early, mid, late indicating if the date is a sowing date, which relative sowing date it is (easy, mid, or late) for a given site-year. 'na' indicates the date is not a sowing date.
- precip_in: daily precipitation in inches
File: RYE_SRxPD_GCmodelCoefs.csv
Description: Cereal rye ground cover model coefficients extracted from non-linear asymptotic regression models of cereal rye ground cover in response to sowing date and seeding rate by site-year.
Variables
- year: indicates year in which biomass was harvested. 2022 indicates experiment was initiated fall 2021 and harvested spring 2022; 2023 indicates experiment was initiated fall 2022 and harvested spring 2023.
- site: location identifier (BARC=Beltsville Agricultural Research Center; CT=Connecticut; DE=Delaware; MA=Massachusetts; NY=New York; PA=Pennsylvania; UMD=University of Maryland Wye Research & Education Center; VT=Vermont)
- pd: relative date of cereal rye sowing (1 = early, 2 = middle, 3 = late)
- d: upper limit (maximum ground cover)
- se.d: standard error of d
- e: steepness of increase as seeding rate increases
- se.e: standard error of e
- ed90: seeding rate necessary to reach 90% of the maximum ground cover
- se.ed90: standard error of ed90
File: edaphic.gdds.summary
Description: output file generated in R summarizing soil and growing degree days for each sowing date by site-year. 'NA' used for blank cells and indicates soil tests were not taken for a given sowing date.
Variables
- blank column: auto-generated row numbers.
- site: location identifier (BARC=Beltsville Agricultural Research Center; CT=Connecticut; DE=Delaware; MA=Massachusetts; NY=New York; PA=Pennsylvania; UMD=University of Maryland Wye Research & Education Center; VT=Vermont)
- pd_fac: relative date of cereal rye sowing (1 = early, 2 = middle, 3 = late)
- year: indicates year in which biomass was harvested. 2022 indicates experiment was initiated fall 2021 and harvested spring 2022; 2023 indicates experiment was initiated fall 2022 and harvested spring 2023.
- soil_n: soil nitrate at sowing (cadmium reduction method)
- soil_p: soil phosphorus at sowing (melich-3 method)
- soil_OM: soil organic matter at sowing (loss on ignition)
- soil_pH: soil pH at sowing (water method)
- GDD_anthesis: growing degree days (base 4.4C) calculated from sowing to harvest
File: Rye_SRxPD_Analysis.Rmd
Description: R markdown including all code used for statistical analysis and figures.
Code/software
Workflow
Downloading the zip file and leaving all folders named and nested as-is will allow data to be read and files to be saved using the "here()" package. Some folders will be empty when first downloaded.
Main folder: 'RYE_SRxPD_DataCode' contains 'Rye_SRxPD_Analysis.Rmd' and the following folders:
'data' (holds data that is read into R: RYE_SRxPD_Data.csv; RYE_SRxPD_ModelCoefs.csv; RYE_SRxPD_GCModelCoefs.csv; RYE_SRxPD_Precip.csv)
'data.output' (where data created in R is saved)
'figs' (where main figures are saved)
'figs.bio' (where individual biomass figures are saved)
'figs.gc' (where individual ground cover figures are saved)
Code developed using R statistical software (4.5.1) in R studio (Version 2025.09.0+387).
packages required:
here (v1.0.1)
tidyverse (v2.0.0)
nlme (v 3.1-168)
emmeans (v 1.11.2-8)
patchwork (v 1.3.2)
drc (v 3.0-1)
statforbiology (v 1.0.2)
ggh4x (v 0.3.1)
MuMIn (v 1.48.11)
ggeffects (v 2.3.1)
khroma (v 1.17.0)