FIGURE 3.

The vertical distribution of nitrate-N content was affected by plastic mulching and fertilization mode at different growth stages (A, 49 days after sowing, B, 86 days after sowing, C, 123 days after sowing, and D, 162 days after sowing) in 2014 (mg kg^-1). CK: no fertilizer and no mulching treatment; T0, traditional broadcast nitrogen fertilizer with mulching treatment; T1, basal nitrogen application at a depth of 6 cm with no mulching treatment; T2, basal nitrogen application at a depth of 6 cm with plastic mulching treatment; T3, basal nitrogen application at a depth of 12 cm with no mulching treatment; T4, basal nitrogen application at a depth of 12 cm with plastic mulching treatment.