Maize/soybean intercrop over time has higher yield stability relative to matched monoculture under different nitrogen-application rates

•Maize/soybean intercropping over time improved stability of crop yields.•Soil fertility contribution rate in intercropping was higher compared to monoculture.•Contribution rate of N fertilizer to maize yield stability was greater than soybean.•Influence of fertilizer on yield stability was greater than that of cropping pattern.