Plant and soil samples were taken at 20 days after seedling
throwing in Nanning and at 25 days after transplanting in
Changsha in 2014. In each site, 20 representative hills (excluding
two border hills) of rice plants were selected in each plot. After
uprooting the plants, rhizosphere soil was collected from the soil
portion tightly adhering to the roots by shaking off the loosely
adhering soil (Chen et al., 2013). The rhizosphere soil from each
plot was mixed and separated into two sub-samples. One subsample
was air-dried at room temperature to measure pH and
available N, P and K contents.