Soil changes over 12 yr of conventional vs. conservation management on irrigated rotations in Southern Alberta
Larney, F.J., Pearson, D.C., Blackshaw, R.E., Lupwayi, N.Z. (2017). Soil changes over 12 yr of conventional vs. conservation management on irrigated rotations in Southern Alberta, 97(2), 249-265. http://dx.doi.org/10.1139/cjss-2016-0141
Plain language summary
Our conservaiton (CONS) management practices were soil building with regard to soil organic carbon (SOC) and total nitrogen, while conventional management was soil degrading for these parameters. Total nitrogen was a more sensitive indicator of soil change than SOC, with five of seven rotations showing significant total nitrogen changes over time, compared with three of seven for SOC. The risk of nitrate-N buildup and potential leaching to groundwater was not an issue, with no obvious accumulation of nitrate-N in the soil profile due to rotation or CONS management. Nitrate-N was more heavily influenced by previous crop than rotation or management.
© Her Majesty the Queen in right of Canada 2017. 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.