Two weeks before plot establishment, the field was tilled using a rotary cultivator to a 5 cm depth and was then carefully leveled. One week before rain simulation, three blocks were established on the field; the space between two adjacent blocks was 4 m wide, which severed an aisle. Each block was then divided into 9 plots, each measuring 10.89 m−2 (3.3 m × 3.3 m). On each of the RF and FMRF plots, narrow (15-cm high × 40-cm wide) and wide (10-cm high × 70-cm wide) ridges were prepared (Fig. 1). On each of FMRF plots, the whole land surface was tightly covered with polyethylene film (colorless and transparent, 0.008 mm thick and 1200 mm wide), and the perforations (around 1-cm in diameter; 30-cm apart, matching the plant spacing of 30-cm in a row) were drilled through the film in the furrows using a handheld device. These perforations helped rainwater collected from the ridges to enter the root zone in the FMRF cropping system. The transparent plastic film was used because the low temperature is a limitation for maize production in areas. All the 27 plots were finally covered by big plastic sheets with which the soil water evaporation was blocked during the time before rainfall simulation. This made sure that all soils in the different treatments had the same initial water content at the time of rainfall simulation.