Evaluation of In-Season Nitrogen Management for Summer Maize in North Central China

Table 5

N balance sheet of different N treatments during maize growth season (all data are kg N ha⁻¹).

Site	Treatment	N input			N output		Apparent N loss
		N rate (1)	Initial Nmin^† (2)	Apparent N mineralization^‡ (3)	Crop N uptake (4)	Residual Nmin^§ (5)	(1) + (2) + (3) − (4) − (5)
Hengshui	N0	0	217.4	107.8	178.8c^¶	146.4d	0
	N120 (0/120)	120	217.4	107.8	207.1b	242.0b	−3.9d
	N120 (30/90)	120	217.4	107.8	230.6ab	237.0b	−22.4e
	N120 (60/60)	120	217.4	107.8	246.7a	218.5c	−20e
	N180(0/180)	180	217.4	107.8	212.3b	257.3ab	35.6b
	N180 (45/135)	180	217.4	107.8	217.4b	255.6ab	32.4b
	N180(90/90)	180	217.4	107.8	239.1ab	246.8b	19.3c
	N240 (0/240)	240	217.4	107.8	239.5ab	271.9a	53.8a
Xinji	N0	0	156.6	60.6	103.2c	114.0d	0
	N120 (0/120)	120	156.6	60.6	124.1b	154.9ab	51.2c
	N120 (30/90)	120	156.6	60.6	153.4a	131.1c	45.7c
	N120 (60/60)	120	156.6	60.6	146.8ab	138.5c	44.9c
	N180 (0/180)	180	156.6	60.6	137.3b	156.1ab	96.8b
	N180 (45/135)	180	156.6	60.6	150.7ab	149.0bc	95.5b
	N180 (90/90)	180	156.6	60.6	154.1a	142.7bc	93.4b
	N240 (0/240)	240	156.6	60.6	155.4a	164.9a	129.9a

^† Initial Nmin: soil mineral N in 0–100 cm soil layer before planting. ^‡Apparent N mineralization during growing season was calculated by (3). ^§Residual Nmin: soil mineral N in 0–100 cm soil layer after harvest. ^¶Within each column, means followed by different letters are significantly different (𝑃<0.05).