Cover crop (CC) growth and biomass production in the Mid-Atlantic region can be limited when CC are planted in the fall following harvest of double crop soybean due to late fall cool temperatures. Interseeding CC in summer prior to soybean canopy cover can improve establishment and spring biomass production. This practice can also increase the diversity of available CC species, help reduce weed pressure and reduce nutrient losses. This study was initiated to evaluate, during the following corn (Zea mays L.) phase, the effects of interseeded CC on soil temperature, soil water balances, evapotranspiration, infiltration, and yield and water use efficiency of corn. The study was conducted at the USDA Beltsville Agricultural Research Center, Beltsville, MD from 2017 through 2020. The cropping systems under study were primarily sequences of corn-soybean (Glycine max L.)-wheat (Triticum aestivum L.)-double crop soybean all planted with no-tillage management. No cover crops (NC) were grown prior to corn in Systems 3 and 4. In System 5, a cover crop (CC) mixture of rye (Secale cereale L.)-hairy vetch (Vicia villosa Roth)-crimson clover (Trifolium incarnatum L.) was interseeded into DCS prior to soybean canopy closure. In System 6, red clover (rc, Trifolium pratense L.) was interseeded into wheat in March and rye was planted into rc after wheat harvest in July.

Meta information about the study in the Word document file CCSP 2023 AGWAT Metadata.doc describes data collection procedures and methods used to replace errors in the sensor data. Additional background information, including Tables 1 through 4 of the manuscript, are the Excel file CCSP Experiment Setup Info Tables 1 Through 4.xlsx. This file includes a schematic of the crop rotation sequences, a list of the cropping system treatments, soil water and temperature sensor types and placement, and beginning and ending measurement periods. Daily values of profile soil water (mm) and soil temperature (C) for the four years and are included in the Excel file CCSP Soil Temperature And Soil Water By Depth.xlxs. These data were used to estimate daily evapotranspiration (ET) and infiltration as described in the manuscript and in the Word document CCSP 2023 AGWAT Metadata.docx of meta information. Weather data including daily precipitation, max and min temperatures, net solar radiation, and windspeed collected at a nearby weather station are provided in two files; one used to estimate growing degree days CCSP Weather 2017-2002 Rain And Air Temp For GDD.xlxs and the other to calculate potential ET CCSP ET Calc Input Output Data and Meta Info.xlsx. Cover crop biomass (kg/ha) prior to corn planting and corn yields (Mg/ha) for the four years are in the Excel file CCSP Corn Yield Cover Crop Biomass.xlsx. Data are provided at the replication, treatment, depth, date, and year levels as appropriate.

Resources in this dataset:

• Resource Title: CCSP 2023 AGWAT Metadata
  File Name: CCSP 2023 AGWAT Metadata.docx
  Description: Word document of meta information that describes data collection procedures, estimation of ET and infiltration, and methods used to replace sensor data having errors.

• Resource Title: CCSP Experiment Setup Info Tables 1 Through 4
  File Name: CCSP Experiment Setup Info Tables 1 Through 4.xlsx
  Description: Background information including Tables 1 through 4 of the manuscript, are contained in this Excel file. Include the following: A schematic of the crop rotation; Table 1 provides a list of the cash crops and cover crops making up the four cropping systems; Table 2 provides the corn planting and harvest dates, cumulative growing degree days (CumGDD oC), rainfall, and sensor measurement periods during the corn growing season; Table 3 provides information on the soil sensors including numbers per plot, sensor waveguide lengths, depths measured, and horizon thicknesses for estimating water volume; and Table 4 provides the average monthly air temperature and rainfall estimated from 2011 through 2020 data.

• Resource Title: CCSP Corn Yield Cover Crop Biomass
  File Name: CCSP Corn Yield Cover Crop Biomass.xlsx
  Description: Cover crop biomass (kg/ha) prior to corn planting and corn yields (kg/ha) data for 2017 through 2020 are i=in this file. Data are provided at the replication and cropping system treatment level for each year. Details about cover crop biomass sampling are contained in the manuscript. Corn yields were collected via a yield monitor on the crop combine. Yields were adjusted to standard moisture content of 15.5 percent.

• Resource Title: CCSP ET Calc Input Output Data And Meta Info
  File Name: CCSP ET Calc Input Output Data And Meta Info.xlsx
  Description: Weather data used as inputs to ETCalc, an online evapotranspiration calculator (Danielescu, 2021 and 2022). The online calculator is at https://etcalc.hydrotools.tech/pageMain.php. Daily potential evapotranspiration (PET) was estimated based on the Penman Montieth method. The input and output data along with meta data to run the calculator are provided in separate tabs of the excel file. The first tab provides additional meta information.

• Resource Title: CCSP Weather 2017-2020 Rain And Air Temp For GDD
  File Name: CCSP Weather 2017-2020 Rain And Air Temp For GDD.xlsx
  Description: Weather data including daily precipitation and max and min temperatures collected at a nearby weather station used to estimate growing degree days are in this excel file. The data and calculations are presented in a tab for each year.

• Resource Title: CCSP Soil Temperature And Soil Water By Depth
  File Name: CCSP Soil Temperature And Soil Water By Depth.xlsx
  Description: Volumetric soil water content (m3/m3) (VWC) and soil temperature, collected at 1 hr (2017) and 15-minute intervals (2018-2020) using time domain reflectometry sensors placed at 4 depths in each plot of 2 or 3 field replications. VWC was converted to mm water for each soil horizon and summed for the whole soil profile (0 to 862 mm). Interval measurements were averaged to daily values of soil water (mm) and soil temperature (C) for the four years and are included in this Excel file. Soil water storage and soil temperature data for each replication, cropping system treatment, and horizon depth are provided in separate tabs for each year.