Soil quality indices as affected by long‐term burning, irrigation, tillage, and fertility management

Abstract

AbstractUnderstanding 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.