DOI: 10.5061/dryad.0vt4b8h75
title: Long-term tillage and cover cropping differentially influenced soil nitrous oxide emissions from cotton cropping system

description: Climate-smart agricultural practices, such as no-tillage (NT) and cover
 cropping, have been widely adopted and are anticipated to yield multiple
 benefits, including soil carbon sequestration, enhancing soil health, and
 crop yield stability. However, their influence on nitrous oxide (N2O)
 emissions varies, with the potential of both increasing and decreasing N2O
 emissions. Increasing N2O emissions under these practices may potentially
 offset the climate mitigation benefits from increased soil carbon
 sequestration. We investigated N2O emissions in response to 42 years of
 long-term adoption of NT and legume cover crop, under nitrogen rates of 0
 and 67 kg N ha-1, in a continuous cotton system in the Southeastern US.
 Intensive manual chamber-based measurements were conducted over two
 growing seasons (2021-2022 and 2022-2023). Long-term NT did not
 significantly (p &gt; 0.05) affect cumulative N2O emissions during the
 study period. Hairy vetch cover crop-grown plots emitted 2-3 times more
 N2O than those without cover crops in 2021-2022, with no significant
 effect observed in 2022-2023. Cumulative emissions in cover crop plots
 were greater compared to those in no cover crop plots when fertilized with
 67 kg N ha-1 in 2021-2022; however, this trend did not persist in
 2022-2023. While interannual variability exists, our results generally
 suggest that long-term NT may not increase N2O emissions, hence its
 adoption could enhance its broader soil health and climate benefits via
 soil carbon sequestration. Whereas managing legume cover crop residues in
 N-fertilized systems is critical to mitigate N2O emissions.
description: # Long-term Tillage and Cover Cropping Differentially Influenced Soil
 Nitrous Oxide Emissions from Cotton Cropping System
 [https://doi.org/10.5061/dryad.0vt4b8h75](https://doi.org/10.5061/dryad.0vt4b8h75) ## Description of the data and file structure This study aimed to evaluate the long-term impact of no-till (NT) practices and cover crops on nitrous oxide (N₂O) emissions in interaction with nitrogen (N) fertilization in a continuous cotton cropping system in the Southeast US. The experiment was designed using a split-split plot layout, with selected experimental levels including two N rates (0, NF; 67 kg N ha⁻¹, F), two cover crop treatments (hairy vetch, HV; no cover crop, NC) in the sub-plot, and two tillage methods (conventional tillage, CT; no-till, NT) in the sub-sub plot, replicated four times. N₂O emissions and soil data were collected from November 2021 to October 2023. Soil samples from a 0-10 cm depth were periodically collected and analyzed for ammonium (NH₄⁺), nitrate (NO₃⁻), and permanganate-oxidizable carbon (POXC). NH₄⁺ and NO₃⁻ were extracted using a 2M KCl solution and analyzed colorimetrically with a Microplate reader (BioTek Instruments, Winooski, VT) (Doane and Horwáth, 2003; Forster, 1995). The POXC was determined using the protocol of Culman et al. (2012). N₂O measurements were conducted with an ICOS analyzer (ABB Los Gatos Research Inc.) using a flow-through closed loop static closed chamber technique, alongside soil moisture and temperature measurements to a depth of 20 cm at each gas sampling. ### Files and variables #### File: Dhaliwal\_et\_al\_2024\_AGRONJ.xlsx **Description:** The Excel file contains two sheets (**"N2O+CO2+VWC+temp"** and **"Soil biogeochemical"**), each representing different data types collected from the experiment from November 2021 to October 2023. Missing data cells were indicated as "NA". The file is organized as follows: ##### Variables * **N Rate**: Two levels of nitrogen application: NF- 0 kg N ha⁻¹ and F- 67 kg N ha⁻¹ * **Cover Crop**: Hairy vetch (HV) and no cover crop (NC) * **Tillage**: Conventional disk tillage (CT) and no-till (NT) * **Replications**: Four replications for each treatment combination (R1, R2, R3, and R4) * **Sampling date**: Date of sampling as mm/dd/yy * **N₂O flux**: Daily nitrous oxide emissions (g N ha-1 day-1) * **CO2 flux:** Daily carbon dioxide emissions (kg C ha-1 day-1) * **Volumetric soil moisture:** Volumetric soil moisture at 0-20 cm depth, recorded as percentage (%) * **Soil temperature:** Soil temperature at 0-20 cm depth, recorded in degrees Celsius (°C) * **Soil NH₄⁺**: Soil ammonium concentration at 0-10 cm depth (mg N kg-1 soil) * **Soil NO₃⁻**: Soil nitrate concentration at 10 cm depth (mg N kg-1 soil) * **POXC**: Permanganate-oxidizable carbon at 10 cm depth (mg C kg-1 soil)