Fig 1.
The temperature, daylight hour, precipitation and evapotranspiration during the cropping seasons from 2012 to 2014.
Fig 2.
Maize-soybean relay intercropping system in August.
Left side is RN treatment plot, right side is NN treatment, and the yellow line is the plot boundary.
Fig 3.
Effect of N application rates on competition ratio and system productivity index of the maize-soybean intercropping systems from 2012 to 2014.
CRSM: yield competition ratio, SPI: system productivity index; Different lower case letters in the same column indicate significant differences (LSD, P < 0.05).
Table 1.
Effects of N application rates on the land equivalent ratio (LER) of maize-soybean relay intercropping.
Fig 4.
Effect of different below-ground interactions and N application rates on maize root distribution at the early grain-filling stage.
MM with different N application rates (A), IM with different N application rates (B); the X-axis indicates depth (20 cm per layer) and the Y-axis indicates sampling interval (10 cm per interval); N application rates are 0, 180 kg N ha-1 (shared by soybean and maize), and 240 kg N ha-1 (180 kg N ha-1 for maize and 60 kg N ha-1 for soybean), respectively, the same as below.
Fig 5.
Effect of different below-ground interactions and N application rates on soybean root distribution at the R2 stage of development in 2014.
MS with different N application rates (A), IS with different N application rates (B), the coordinate axis and N application rates were same as Fig 4.
Table 2.
Effect of planting patterns and N application rates on crop dry matter accumulation (Mg ha-1).
Table 3.
N uptake of maize and soybean under different N levels and planting patterns (kg ha-1).
Table 4.
Effect of planting patterns and N application rates on nitrogen use efficiency (%) in the maize-soybean relay strip intercropping system.