Due to anaerobic conditions that develop in soils under flooded-rice (Oryza sativaL.) production, along with the global extent of rice production, it is estimated that rice cultivation is responsible for 11% of global anthropogenic methane (CH₄) emissions. In order to adequately estimate CH₄emissions, it is important to include data representing the range of environmental, climatic, and cultural factors occurring in rice production, particularly from Arkansas, the leading rice-producing state in the US, and from clay soils. The objective of this study was to determine the effects of previous crop (i.e., rice or soybean (Glycine maxL.)) and cultivar (i.e., Cheniere (pure-line, semidwarf), CLXL745 (hybrid), and Taggart (pure-line, standard-stature)) on CH₄fluxes and emissions from rice grown on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts) in eastern Arkansas. Rice following rice as a previous crop generally had greater (p<0.01) fluxes than rice following soybean, resulting in growing season emissions (p<0.01) of 19.6 and 7.0 kg CH₄-C ha⁻¹, respectively. The resulting emissions from CLXL745 (10.2 kg CH₄-C ha⁻¹) were less (p=0.03) than those from Cheniere or Taggart (15.5 and 14.2 kg CH₄-C ha⁻¹, resp.), which did not differ. Results of this study indicate that common Arkansas practices, such as growing rice in rotation with soybean and planting hybrid cultivars, may result in reduced CH₄emissions relative to continuous rice rotations and pure-line cultivars, respectively.

Understanding the impacts of long‐term agricultural practices on soil quality (SQ) is key for sustaining agroecosystem productivity. This study investigated conventional and no‐tillage (NT), residue burning and no burning, residue level (high and low), and irrigation (irrigated and dryland) effects on soil properties, SQ, and crop yields following 16 yr of a wheat ( Triticum aestivum L.)–soybean [ Glycine max (L.) Merr.] double‐crop system via the Soil Management Assessment Framework (SMAF). A field experiment was conducted in the Lower Mississippi River Delta region on a silt‐loam soil. Bulk density, soil organic C (SOC), total N (TN), pH, electrical conductivity (EC), and soil P and K from the 0‐ to 10‐cm soil depth were used as SQ indicators investigated individually and as an overall soil quality index (SQI). Following 16 yr, residue burning reduced SOC (1.1%) compared with no burning (1.24%). Irrigation resulted in greater soil TN than dryland management systems ( p  < 0.05). Reduced soil pH and extractable soil P and K occurred under NT, high residue, and irrigated treatments. Irrigation increased soybean yields, regardless of the tillage system. Burned, NT–high residue management increased wheat yields (3.45 Mg ha ⁻¹ ). Irrigation reduced SQ because of low EC and K scores. High residue reduced SQ compared with the low residue treatment within NT systems, owing to low pH scores. The SMAF indices identified the impacts of irrigation, NT, and optimal N fertilization on SQ. Monitoring of soil pH, P, and K may be needed to maintain SQ in long‐term wheat–soybean systems.