Season-Long Time-Series Analysis of Soil Respiration in Furrow-Irrigated Corn with and Without Cover Crop in the Lower Mississippi River Basin

Temporal resolution of carbon dioxide (CO2) release from the soil at the field scale is not completely understood. The objectives of this study were to identify trends, repetitive cycles, and residual patterns and structures with a time-series analysis from a furrow-irrigated corn (Zea mays L.) field with and without cover crops (i.e., CC and No-CC, respectively) over the course of one growing season in the Lower Mississippi River Basin. Carbon dioxide fluxes were measured from 5 May to 18 August 2024, four times a day (i.e., 0300, 0900, 1500, and 2100 h) from each of the two CC treatments. Linear trends were significant, but they were only able to explain 3 and 10% of the CO2-flux variability for CC and No-CC, respectively. Spectral density analyses indicated the significant presence of repetitive patterns every four lags, the amplitude of which was numerically 25% greater for CC than for No-CC. The structure of the residual was best described by separate autoregressive-moving-average (ARMA) models for the CC and No-CC treatments. The current study provides preliminary yet fundamental information to improve the understanding of the dynamics of soil respiration processes from a row-crop production system.