LAUSR

Abstract: Increased irrigated production of potato (Solanum tuberosum L.), dry bean (Phaseolus vulgaris L.), and sugar beet (Beta vulgaris L.) in southern Alberta in the 1990s prompted a 12 yr (2000–2011) study to evaluate conservation (CONS) management practices for these crops in 3–6 yr rotations. Conservation management included reduced tillage, cover crops, compost, and narrow-row dry bean. After 12 yr, soil organic carbon (SOC) at 0–30 cm depth increased by 0.48 Mg ha-1 yr-1 on a 5 yr CONS rotation, in line with average cumulative compost addition of 154 Mg ha-1. In contrast, SOC stocks on a 3 yr conventional (CONV) rotation, which did not receive compost, declined by 0.25 Mg ha-1 yr-1. Nitrate-N did not accumulate in the soil profile under CONS management, as it was largely influenced by previous crop. In contrast, available P increased with compost addition under CONS management, leading to surface buildup and downward movement in the soil profile. At 0–120 cm depth, the CONS rotations showed 26%–53% higher available P than CONV rotations between 2005 and 2011. Apart from a caveat regarding potential P accrual, the CONS management package in this study was validated as soil building for irrigated cropping systems in southern Alberta.