Surface Soil Quality Attributes following 12 Years of Conventional and Conservation Management on Irrigated Rotations in Southern Alberta

Abstract

Rapid expansion of irrigated row crop production, viz., potato (Solanum tuberosum L.), dry bean (Phaseolus vulgaris L.), and sugar beet (Beta vulgaris L.), in southern Alberta in the late 1990s provided the impetus for a 12‐yr (2000–2011) study to evaluate cropping systems that maintained or improved soil quality. The study compared conservation (CONS) and conventional (CONV) management in rotations of 3‐ to 6‐yr duration. Conservation management included reduced tillage, cover crops, feedlot manure compost addition, and solid‐seeded narrow‐row dry bean production. After 12 yr, particulate organic matter C (POM‐C) and N (POM‐N) showed >145% increases (POM‐C, 2.2–5.8 Mg ha−1; POM‐N, 0.20–0.49 Mg ha−1) with CONS management compared with 45 to 50% increases in total organic C and N (TOC, 10.2–15.3 Mg ha−1; TN, 1.06–1.53 Mg ha−1) and 20% increases in fine organic matter (FOM)‐C and ‐N (FOM‐C, 8.3–10.1 Mg ha−1; FOM‐N, 0.87–1.04 Mg ha−1). Aggregate stability of the pre‐wet >1‐mm fraction increased significantly from 13% under CONV to 21% under CONS management. Overall, the 5‐yr CONS rotation (sugar beet–wheat (Triticum aestivum L.)–dry bean–potato–wheat) ranked highest for soil quality (100%), with CONV rotations substantially lower (33–38%). Adoption of CONS management enhanced a wide range of soil quality attributes that could safeguard sustainable expansion of irrigated specialty cropping in southern Alberta.