Crop residues integration with nitrogen rates reduces yield-scaled nitrous oxide emissions and improves maize yield and soil quality

Figures & data

Figure 1. Weather data for Mymensingh’s muktagacha (2021–22; December-June); column graph indicates the amount of rainfall (mm) in the primary axis, while the line graph demonstrated the maximum and minimum temperature (red; maximum, blue; minimum) with secondary axis.

Figure 2. Time course ± SE of N₂O emissions in response to (a) different levels of residue and (b) N fertilizer rate in maize field; crop residue retention = CR and No residue = NR; FP = farmers’ practice, RD = recommended dose, 1.25 RD = 125% of recommended dose; arrows indicate the day of split urea application.

Table 1. Interaction effect of crop residue and different N fertilization rates on mean, cumulative N₂O emissions and the emission factor (EF%) in maize field (n = 3; mean ± SE).

Residue	N-rate	Mean N2O fluxes (g N ha^−1 d^−1)	Cumulative N2O fluxes (g N ha^−1)	EF (%)
NR	Control	2.2 ± 0.1 g	145.4 ± 6.8 g
	FP	24.8 ± 0.7 e	1637.5 ± 47.7 e	0.99 ± 0.03 d
	RD	39.7 ± 0.9 c	2622.9 ± 56.9 c	1.11 ± 0.03 c
	1.25 RD	54.3 ± 0.6 b	3583.3 ± 38 b	1.23 ± 0.01 b
CR	Control	2.9 ± 0.1 f	193.6 ± 9 f
	FP	27.2 ± 1.7 d	1794.8 ± 109.5 d	1.06 ± 0.07 cd
	RD	39.9 ± 0.4 c	2634.2 ± 29 c	1.09 ± 0.01 c
	1.25 RD	59.5 ± 0.4 a	3930 ± 24.8 a	1.34 ± 0.01 a
Statistics (p < 0.05)
Residue (R)		**	**	*
Fertilizer (F)		***	***	***
R × F		**	**	*

Crop residue incorporation = CR and No residue = NR; FP = Farmer’s practice, RD = Recommended dose, 1.25 RD = 125% of Recommended dose; mean ± standard error with different letters varies significantly where *means p < 0.05, **means p < 0.01, ***means p < 0.001.

Table 2. Interaction effect of crop residue and different N fertilization rates on soil SOC, TN, P, K, S content and pH (n = 3; mean ± SE).

Residue	N-rates	SOC (%)	TN (%)	K (meq./100 g soil)	Available S (ppm)	Available P (ppm)	Soil pH
NR	Control	0.47 ± 0.01 d	0.08 ± 0 d	0.11 ± 0.02 d	9.05 ± 0.02 d	4.2 ± 0.32 e	6.05 ± 0 c
	FP	0.53 ± 0.01 cd	0.11 ± 0.01 bcd	0.19 ± 0.02 abc	17.97 ± 0.97 c	9.52 ± 0.01 c	6.17 ± 0.03 bc
	RD	0.57 ± 0.01 bc	0.11 ± 0.01 bcd	0.16 ± 0.03 cd	21.7 ± 1.27 bc	19.56 ± 1.15 a	6.32 ± 0.04 bc
	1.25 RD	0.59 ± 0.02 bc	0.13 ± 0.01 abc	0.18 ± 0.02 bcd	31.29 ± 0.42 a	14.97 ± 0.43 b	6.45 ± 0.02 ab
CR	Control	0.55 ± 0.03 cd	0.10 ± 0.01 cd	0.17 ± 0.01 cd	19.83 ± 3.06 bc	4.52 ± 2.59 d	6.13 ± 0.04 c
	FP	0.65 ± 0.01 ab	0.13 ± 0.01 abc	0.14 ± 0.01 cd	23.92 ± 2.02 b	13.32 ± 2.31 b	6.20 ± 0.03 bc
	RD	0.70 ± 0.01 a	0.15 ± 0.01 ab	0.27 ± 0.01 a	23.23 ± 1.73 b	16.88 ± 2.37 ab	6.45 ± 0.01 ab
	1.25 RD	0.70 ± 0.01 a	0.16 ± 0.01 a	0.25 ± 0.03 ab	31.72 ± 2.02 a	16.65 ± 2.13 abc	6.70 ± 0.04 a
Statistics (p < 0.05)
Residue		**	*	**	*	*	*
N fertilizer		***	***	*	*	*	*
Residue * Fertilizer		**	**	*	*	**	**

Crop residue incorporation = CR and No residue = NR; FP = Farmers’ practice, RD = Recommended dose, 1.25 RD = 125% of Recommended dose; mean ± standard error with different letters varies significantly where *means p < 0.05, **means p < 0.01, ***means p < 0.001.

Table 3. Estimated coefficients of physico-chemical properties selected as significant explanatory variables using a stepwise procedure for the model of N₂O emissions (n = 24).

Cumulative N2O fluxes (g N ha^−1)	Equation element	Estimate	s. e.	p-Value	Partial R^2
Ln N2O	Intercept	18.5	2.96	***
	N rate (kg/ha)	0.01	0.00	***	0.93
	% OC	2.8	0.99	*	0.27
	% TN	1.7	3.71	*	0.45
	pH	−2.5	0.52	**	0.65

Figure 3. Interaction effect of crop residue and different N fertilization rates on maize yield; crop residue retention = CR and No residue = NR; FP = farmers’ practice, RD = recommended dose, 1.25 RD = 125% of recommended dose; bars with different letters vary significantly from each other at p < 0.05.

Figure 4. Interaction effect of crop residue and different N fertilization rates on yield-scaled N₂O emissions in maize field; crop residue retention = CR and No residue = NR; FP = farmers’ practice, RD = recommended dose, 1.25 RD = 125% of recommended dose; bars with different letters vary significantly from each other at p < 0.05.

Data availability statement

The authors agree to make data and materials supporting the results or analyses presented in their paper available upon reasonable request.