Table 3. Annual loads of nitrogen and phosphorus transported by surface runoff for the treatments T0, T1, and T2 from January to December 2018.
| Treatment | Runoff (×105 L ha-1) | Fertilizer amount (kg ha-1) | Nitrogen and phosphorus losses in runoff (kg ha-1) | Loss ratio (%) | AEN (kg kg-1 N) | AEP (kg kg-1 P) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TN | TP | TN | NO3--N | NH4+-N | TP | DP | TN | TP | ||||
| T0 | 50.0±0.6a | 0 | 0 | 24.67±2.40b | 7.77±1.20b | 1.03±0.13a | 0.51±0.03b | 0.42±0.02b | — | — | — | — |
| T1 | 50.6±0.3a | 273 | 59 | 43.39 ±14.04a | 11.63 ±1.15a | 1.20 ±0.29a | 0.67 ±0.04a | 0.56±0.03a | 15.89±5.14a | 1.13±0.08a | 16.58±0.42b | 76.72±1.94b |
| T2 | 50.4±1.1a | 240 | 52 | 22.17 ± 1.07b | 9.25 ± 0.94b | 1.18 ±0.32a | 0.68 ± 0.08a | 0.54± 0.08a | 9.24±0.45b | 1.31±0.16a | 22.02±2.38a | 101.61±11.00a |
Notes: T0 = Traditional irrigation; T1 = Traditional irrigation and fertilization practice; T2 = Water-saving irrigation and optimizing fertilization.N: Nitrogen; P: Phosphorus; Loss ratio, total nitrogen (phosphorus) loss loading/amount of applied nitrogen (phosphorus); AEN (P), agronomic N (P) use efficiency, increased grain yield/unit N (P) application. TN: Total N; NO3−−N: Nitrate N; NH4+−N: Ammonium N; TP: Total P; DP: Dissolved P. Values (means ± SD) with different lower-case letters in a column are significantly different at P < 0.05 according to the Duncan test.