Economic effect of fall vs. spring plowing of forage on following potato production in Prince Edward Island, Canada

Fall plowing of forage in a typical barley-forage-potato rotation in Prince Edward Island (PEI), Canada has led to negative environmental impacts, including soil erosion and nitrate leaching to groundwater. Data from four experimental locations in PEI were assessed from 2009 to 2016 in order to determine the effects of delaying plow-down of forage in a barley-forage-potato rotation from fall to spring on economic returns and risk of returns for potato producers. Factors related to fall or spring plowing such as soil erosion, nitrate leaching, seedbed preparation and planting date, effect on weeds, insects and diseases, potato harvest loss, and additional labour and time constraints, were quantified and included in the assessment. Without including these factors, there was no difference between fall and spring plowing of forage in terms of potato yield and net revenue. However, when these factors were included and data were pooled together, late fall plowing was preferred over spring plowing for potato growers who are avoiding risk. Potato growers are reluctant to shift plowing to spring due to the significant uncertainty and risk associated with this practice, and would be required to be paid more than $600 ha-1 yr-1 to be indifferent between fall tillage and delaying tillage until spring. While spring tillage provides significant reductions in the risk of soil erosion and nitrate leaching, it affects potato yield and production risk and, therefore, leads to loss of net income. If farmers are not paid for their loss of income, they should be encouraged to do their tillage as late as possible in the autumn and replace it with other reduced or conservation tillage practices.