Climate change, agricultural inputs, cropping diversity, and environment affect soil carbon, phosphorus, and nitrogen: a case study in Saskatchewan
Lychuk, T.E., Moulin, A.P., Lemke, R., Izaurralde, R., Johnson, E., Olfert, O., Brandt, S. 2018. Climate change, agricultural inputs, cropping diversity, and environment affect soil carbon, phosphorus, and nitrogen: a case study in Saskatchewan, Canada, Manitoba Soil Science Society Annual Meeting, Winnipeg, Manitoba, Feb 1, 2018
Résumé en langage clair
Climate change will significantly affect soil C and N due to the influence of increased precipitation and temperature during the growing season. Soil properties simulated with the EPIC model showed significant differences between combinations of crop rotation and levels of input for fertilizer and tillage, in a range from organic to conventional. Cropping systems with diverse annual crops and reduced tillage with fertilizer added based on soil test maintained soil C and N relative to other management.
The relative impact of climate change, management, diversity, and environment on soil carbon, nitrogen, and phosphorus has seldom been assessed in the scientific literature. Experimental results for a case study of the effects of agricultural inputs and cropping diversity on environmental quality were previously assessed with the Environmental Policy Integrated Climate (EPIC) model. Three levels of agricultural inputs [organic (ORG), reduced (RED), and high (HI)] and sub-plots comprised of three levels of cropping diversity [low (LOW), diversified annual grains (DAG), and diversified annual perennial (DAP)] were used in this study. This modeling study assessed soil organic carbon (SOC), CO2 emissions from microbial respiration (CO2-MR), nitrate leaching, and labile phosphorus (P) content (0-15 cm) simulated with the EPIC model for historical (1971-2000) and future climate scenarios (2041-2070) under A2 high emissions global scenario. Under climate change, SOC decreased by 1.3% of original stocks in the 0-90 cm. Emissions and nitrate losses increased by 17 and 28%, respectively, while labile P decreased by 12%. Precipitation in May accounted for 16% of total variation in SOC. June temperature accounted for 9% of variation in CO2-MR. The combination of input and diversity was correlated with 3, 7, 23, and 20 percent of variation in SOC, CO2-MR, NO3-N losses, and labile P, respectively. The combination of RED inputs and DAG diversity reduced the impact of climate change on SOC, CO2, and nitrate losses.