Modeling Effects of Climate Change, Agricultural Inputs, Cropping Diversity, and Environment on Soil Nitrogen and Phosphorus: a Case Study in Saskatchewan, Canada
Agriculture in Canada will be influenced by the effects of climate change in the coming decades. Canadian producers can adapt to environmental change by changing rotation, varying fertilizer, tillage and other crop inputs. This modeling study assessed soil nitrate-N (NO3-N) leaching and labile soil phosphorus (P) simulated with the Environmental Policy Integrated Climate (EPIC) model for historical weather (1971-2000) and future climate scenarios (2041-2070) for the Alternative Cropping Systems (ACS) study research site in Saskatchewan, Canada. The ACS study consisted of three levels of agricultural inputs [organic (ORG), reduced (RED), and high (HI)] and three levels of cropping diversity [low (LOW), diversified annual grains (DAG), and diversified annual & perennial (DAP)]. The objective of this modeling study was to identify one or more management systems which reduce the environmental impact of climate change on NO3-N leaching and labile soil P. Nineteen years of field and crop management information from the 1994-2013 ACS study were input to the EPIC model. Changes in NO3-N and P under climate change were explored with recursive partitioning in multivariate analyses of inputs, diversity, growing season precipitation (GSP), and growing degree days (GDD) and terrain attributes (TA). Under climate change, NO3-N losses increased by 28% (from 27.1 to 34.7 kg ha-1 y-1), while labile soil P decreased by 12% (from 24.7 to 21.6 kg ha-1 y-1). Summer precipitation explained 12% of total variation in future NO3-N losses. The combination of input and diversity was correlated with 23 and 20 percent of variation in NO3-N losses and labile P, respectively. Cropping diversity was most significant, with reduced NO3-N leaching and labile P under climate change, accounting for 22 and 13% of total variation, respectively. The combination of RED inputs and DAG diversity reduced the impact of climate change on NO3-N losses and soil P and may provide a sustainable, adaptive solution for farming with regards to upcoming seasonal variations in temperature and precipitation.