Table 4.

N uptake and NRE under different combinations of BC and N levels.

Treatment	Straw N uptake (kg ha-1)		grain N uptake (kg ha-1)		total N uptake (kg ha-1)		NRE (%)
	2021	2022	2021	2022	2021	2022	2021	2022
C0N1	55.87 ± 3.06d	56.41 ± 0.76cd	54.97 ± 1.50d	58.57 ± 3.78c	110.83 ± 2.56e	114.99 ± 4.54d	33.25 ± 0.57cd	34.40 ± 2.88bc
C0N2	53.98 ± 3.73d	58.75 ± 1.96cd	56.52 ± 0.88d	58.92 ± 2.51c	110.50 ± 3.51e	117.34 ± 4.14d	26.23 ± 1.95e	27.31 ± 2.103cd
C0N3	60.91 ± 4.05bcd	53.95 ± 1.38d	67.01 ± 3.94bc	68.42 ± 2.11b	127.92 ± 2.94d	122.37 ± 1.86d	28.73 ± 1.31de	23.67 ± 2.33cd
C1N1	67.76 ± 2.20ab	62.66 ± 1.68bcd	71.57 ± 3.28b	69.87 ± 1.52b	139.33 ± 5.47bc	132.53 ± 2.51c	50.68 ± 3.23a	47.65 ± 6.16a
C1N2	62.54 ± 1.94bc	58.19 ± 1.65cd	83.07 ± 2.27a	84.83 ± 4.26a	145.60 ± 4.11ab	143.03 ± 3.72b	45.74 ± 2.28a	41.45 ± 5.52ab
C1N3	71.38 ± 1.07a	60.98 ± 5.75bcd	80.60 ± 2.27a	84.39 ± 2.75a	151.98 ± 5.39a	145.37 ± 2.06ab	39.42 ± 2.40b	34.07 ± 2.59bc
C2N1	59.63 ± 3.85d	65.99 ± 1.91bc	55.66 ± 3.93d	56.46 ± 1.81c	115.30 ± 5.58e	122.44 ± 3.61d	38.53 ± 4.14bc	39.73 ± 4.49ab
C2N2	73.35 ± 2.50a	69.69 ± 2.65ab	61.30 ± 3.43cd	61.64 ± 2.78c	134.65 ± 4.20cd	131.33 ± 3.42c	39.65 ± 2.34b	34.81 ± 2.34bc
C2N3	74.97 ± 3.88a	80.13 ± 5.05a	64.21 ± 4.16c	71.27 ± 3.35b	139.18 ± 6.78bc	151.40 ± 6.25a	33.73 ± 3.56cd	36.82 ± 3.45b
C	27.45**	21.12**	78.53**	116.28**	80.16**	73.04**	81.80**	22.33**
N	10.64**	1.05	17.20**	50.06**	29.94**	37.08**	15.29**	11.57**
C·N	5.44**	2.99*	2.73*	6.51**	3.77*	7.19**	4.13**	1.63

Values ​​represent mean ± standard deviation of 3 replicates. * Indicates that the effect is significant at a level less than 0.05, and ** indicates that it is extremely significant at a level less than 0.01. BC application rates: 0 t ha^-1 (C₀), 15 t ha^-1 (C₁) and 30 t ha^-1 (C₂); N application rates: 135 kg ha^-1 (N₁), 180 kg ha^-1 (N₂), 225 kg ha^-1 (N₃). BC was mixed uniformly into the soil at a depth of 30 cm before sowing in 2021 but was not applied in the following year. N fertilizer was applied before sowing in the two years.