Soil carbon sequestration on a maize-mung bean field with rice straw mulch, no-tillage, and chemical fertilizer application in Thailand from 2011 to 2015

Figures & data

Figure 1. Monthly maximum and minimum air temperature, and monthly precipitation at the Lopburi Seed Research and Development Center from 2011 to 2015

Table 1. Field experiment treatments from 2011 to 2015

Treatment	Treatment
No.	Chemical fertilizer	Organic matter input	Tillage
1	No application	No organic matter input	Tillage
2	No application	No organic matter input	No-tillage
3	No application	Rice straw mulch	Tillage
4	No application	Rice straw mulch	No-tillage
5	Application	No organic matter input	Tillage
6	Application	No organic matter input	No-tillage
7	Application	Rice straw mulch	Tillage
8	Application	Rice straw mulch	No-tillage

Chemical fertilizer was applied at 93.75–31.25-31.25 kg N-P₂O₅-K₂O ha⁻¹ under maize cultivation and not under mung bean cultivation.

Rice straw mulch was carried out before maize sowing and not before mung bean sowing.

Tillage and no-tillage were carried out for maize cultivation and for mung bean cultivation.

Table 2. Crop dry matter production from 2011 to 2015

	Crop dry matter production (Mg DM ha^−1 year^−1)
	Maize			Mung bean
Treatments	Seeds	Cobs	Stems and leaves	Seeds	Pod shells	Stems and leaves
NoOM	3.90 ± 0.35	0.81 ± 0.06	5.10 ± 0.36	0.27 ± 0.02	0.17 ± 0.01	0.50 ± 0.04
RS	4.16 ± 0.41 ns	0.84 ± 0.07 ns	6.07 ± 0.59 ns	0.32 ± 0.02 ns	0.22 ± 0.01 **	0.67 ± 0.04 **
Till	4.43 ± 0.33	0.88 ± 0.07	5.85 ± 0.56	0.30 ± 0.02	0.20 ± 0.02	0.60 ± 0.06
NoTill	3.63 ± 0.39 ns	0.77 ± 0.06 ns	5.32 ± 0.45 ns	0.30 ± 0.02 ns	0.19 ± 0.01 ns	0.57 ± 0.04 ns
NoCF	2.98 ± 0.24	0.64 ± 0.04	4.27 ± 0.28	0.27 ± 0.02	0.20 ± 0.02	0.53 ± 0.05
CF	5.09 ± 0.17 ***	1.01 ± 0.03 ***	6.90 ± 0.37 ***	0.32 ± 0.02 ns	0.19 ± 0.01 ns	0.64 ± 0.04 ns

NoOM: no organic matter input; RS: rice straw mulch; Till: tillage cultivation; NoTill: no-tillage cultivation; NoCF: no chemical fertilizer application; CF: chemical fertilizer application.

Average ± standard error.

ns: non-significant, *: P value < 0.05, **: P value < 0.01, ***: P value < 0.001 by t-test.

The crop residues were left in the field.

Table 3. Three-way ANOVA in SOC change from 2011 to 2015 in the experiment in Lopburi

Factor (treatments)	df	Sum Sq	Mean Sq	F value	p
Organic matter (NoOM, RS)	1	0.918	0.918	5.44	0.03	*
Tillage (Till, NoTill)	1	0.019	0.019	0.11	0.74
Chemical fertilizer (NoCF, CF)	1	0.041	0.041	0.24	0.63
Organic matter:Tillage	1	0.025	0.025	0.15	0.71
Organic matter:Chemical fertilizer	1	0.018	0.018	0.10	0.75
Tillage:Chemical fertilizer	1	0.062	0.062	0.37	0.55
Organic matter:Tillage:Chemical fertilizer	1	0.003	0.003	0.02	0.90
Residuals	16	2.702	0.169
Total	23	3.787

NoOM: no organic matter input; RS: rice straw mulch; Till: tillage cultivation; NoTill: no-tillage cultivation; NoCF: no chemical fertilizer application; CF: chemical fertilizer application.

*: p value < 0.05.

Table 4. SOC change, organic C input, and ratio of SOC stock change per total organic C input to soil from 2011 to 2015 in the experiment in Lopburi

					C input to soil (Mg C ha^−1 year^−1)
Treatments	Average of SOC content† (g C kg^−1)	Change of SOC content† (g C kg^−1 year^−1)	Average of SOC stock† (Mg C ha^−1)	Change of SOC stock† (Mg C ha^−1 year^−1)	Stems and leaves	Roots‡	Rice straw, rice husk charcoal	Total	Conversion rate of total C input to SOC stock change§
NoOM	7.45 ± 0.13	0.23 ± 0.03	17.0 ± 0.4	0.52 ± 0.07	2.38 ± 0.16	0.73 ± 0.05	0.00	3.11 ± 0.22	0.175 ± 0.026
RS	8.86 ± 0.20 ***	0.40 ± 0.06 *	20.4 ± 0.5 ***	0.91 ± 0.13 *	2.86 ± 0.26	0.83 ± 0.07	1.36	5.06 ± 0.33 ***	0.181 ± 0.022 ns
Till	8.30 ± 0.28	0.32 ± 0.05	19.1 ± 0.6	0.75 ± 0.11	2.74 ± 0.25	0.83 ± 0.07	0.68	4.26 ± 0.44	0.182 ± 0.027
NoTill	8.01 ± 0.26 ns	0.30 ± 0.06 ns	18.2 ± 0.7 ns	0.69 ± 0.13 ns	2.50 ± 0.20	0.76 ± 0.06	0.68	3.92 ± 0.36 ns	0.174 ± 0.021 ns
NoCF	8.17 ± 0.31	0.30 ± 0.04	18.5 ± 0.8	0.68 ± 0.10	2.04 ± 0.12	0.60 ± 0.04	0.68	3.33 ± 0.29	0.203 ± 0.025
CF	8.14 ± 0.23 ns	0.33 ± 0.06 ns	18.9 ± 0.5 ns	0.76 ± 0.13 ns	3.20 ± 0.16	0.96 ± 0.04	0.68	4.84 ± 0.38 **	0.153 ± 0.020 ns

NoOM: no organic matter input; RS: rice straw mulch; Till: tillage cultivation; NoTill: no-tillage cultivation; NoCF: no chemical fertilizer application; CF: chemical fertilizer application; SOC: soil organic carbon.

Average ± standard error.

ns: non-significant, *: P value < 0.05, **: P value < 0.01, ***: P value < 0.001 by t-test.

† Estimation using SOC data from harvest in 2010 to before plowing in 2016.

‡ Root biomass was estimated to be 16% that of aboveground biomass (Amos and Walters, 2006).

§ Conversion rate of total C input to SOC stock change was calculated as ‘Change of SOC stock’/‘Total C input to soil’.

Amos, B., and D. T. Walters. 2006. “Maize Root Biomass and Net Rhizodeposited Carbon: An Analysis of the Literature.” Soil Science Society of America Journal 70: 1489–1503. doi:10.2136/sssaj2005.0216.

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