plant sample was ground into powder for chemical analysis. Soil sample from 0 to 20 cm layer of each plot was collected after each crop, as well as the soil samples in pots, and after air-dried, was ground by automatic agate mill and sieved into 2 mm and 0.15 mm for chemical...
Plant samples from each treatment were sorted into three categories, shoots (plant components above ground except grains), roots, and grains oven dried for 72 h at 70 °C. A Wiley Hammer Mill with a mesh size of 1 mm was used to crush the oven dried materials in the lab. Total nitroge...