Effects of the border on yield and water use in wheat/maize intercropping in rain-fed areas with different nitrogen levels

•The border effects of wheat/maize strip intercropping were studied.•Border wheat rows received better light, nutrition and moisture conditions.•The border wheat contributed 63.7% of the total wheat output.•The recovery growth of maize was affected by nitrogen and precipitation.•Wheat/maize intercropping improved land productivity in Northwest China.