Adaptation of water and nitrogen management to future climates for sustaining potato yield in Minnesota: Field and simulation study

• The research work is the study of impacts of climate change on irrigated potato production and nitrate leaching and describes alternative management strategies to sustain production in future while limiting nitrate leaching.
• In this study, Climate data modeled at daily intervals for present time slice and mid-century under an A2 emission scenario were taken from the North America Regional Climate Change Assessment Program (NARCCAP) for five climate models. Potato yield, harvest index, water use efficiency, water and N stress, crop N and nitrate leaching were predicted by using the DSSAT crop growth model.
• Without changes in current irrigation or fertilizer rates, climate change would cause future potato yields to decrease by 19–28%, harvest index by 4–9%and water use efficiency by22–32% in Minnesota.

The present study focuses on (i) evaluation of potato crop yield under present time slice (PTS) with recommended management of nitrogen (N) fertilizer and irrigation on sandy soils of Minnesota, USA (ii) simulation of potato productivity and nitrate leaching with the SUBSTOR DSSAT-potato model in a projected future climatic environment (2038–2067) and (iii) evaluation of alternative irrigation and N management strategies with the DSSAT model as adaptation measures to minimize climate change impacts. Ensemble global climate model output for each of three future mid-century (MC) 10-years time slices of crop growing season predicts increases in maximum temperature (Tmax) of 0.7, 1.2 and 2.1 °C; and in minimum temperature (Tmin) of 0.6, 1.3 and 2.0 °C in MC1 (2038–2047), MC2 (2048–2057) and MC3 (2058–2067), respectively, during the tuber bulking periods. Rainfall (RF) of 253.1 mm in PTS decreased by 29.7, 16.7 and 6.5 mm in MC1–MC3, respectively. Under the changed climate, simulations indicated decreases in potato yields of 19–29%, harvest index of 4–9% and water use efficiency of 22–32% compared with current irrigation and fertilizer rates (260 mm irrigation, 270 kg ha−1 N fertilizer). Potato yields could be sustained at present levels by increasing irrigation levels to 390 mm, with 450 kg ha−1 N in the years 2038–2047; and 326 and 390 mm irrigation with 450 kg N ha−1 in year 2048–2057. However, leaching losses in 2048–2057 would increase (relative to current losses) by 34–62%. In the years 2058–2067 yield in the region evaluated can no longer be sustained with increased N and irrigation levels and leaching losses would increase by 41–67%. Use of varieties tolerant to drought and heat or adapting alternative cultural practices will be required to maintain productivity.