Carbon dioxide emission in relation with irrigation and organic amendments from a sweet corn field

Figures & data

Table 1. Soil texture, saturated hydraulic conductivity (K_sat), available water content (θ_aw), Organic carbon (OC), bulk density (ρ_b) and cation exchange capacity (CEC) of Waialua gravelly clay variant (isohyperthermic Pachic Haplustoll) of Waimanalo research station.^[38]

	%
Depth (cm)	Sand	Silt	Clay	OC	Ksat (m d^—1)	θaw (cm^3 cm^−3)	ρb g (cm^—3)	CEC molC (kg^−1)
0–38	11.2	42.9	45.9	1.98	0.34–1.21	0.13	1.18	33.5
38–91	11.4	43.8	44.8	0.80	0.34–1.21	0.14	1.22	28.9

Table 2. Calculations of the recommended dry weight application rates of chicken manure and bone meal based on 3.01 and 10% N contents, respectively. Rates were calculated based on the recommendations by Abbas and Fares.^[18]

	Chicken manure application (kg ha^−1)		Bone meal application (kg ha^−1)
Rate	Dry biomass	Total nitrogen (N)	Dry biomass	Total nitrogen (N)
Low	5,604	169	1,681	168
Medium	11,209	337	3,363	336
High	22,417	675	6,725	673

Table 3. Chemical properties of bone meal and chicken manure: adapted from Abbas and Fares ^[18] and Valenzuela et al.^[39]

	% on dry weight basis
Type	P	K	Ca	Mg	Na	N	OC
Bone meal	0.10	0.35	0.02	0.02	0.65	0.1	47.1
Chicken manure	1.47	1.97	14.3	0.75	0.4	3.01	21.5

Table 4. Analysis of variance results of soil CO₂ flux as a function of irrigation level (IRR), organic amendment type (OA) and rate.

Source	Df	SS	MS	F	P-value
Rep	2	1.51	0.76
IRR	2	0.00	0.00	0.00	1.00
OA	1	6.56	6.56	34.83	0.00
Rate	3	7.83	2.61	13.87	0.00
IRR × OA	2	0.00	0.00	0.00	1.00
IRR × Rate	6	0.00	0.00	0.00	1.00
OA × Rate	3	3.68	1.23	6.52	0.00
IRR × OA × Rate	6	0.00	0.00	0.00	1.00
Error	1198	225.50	0.19
Total	1223	245.07

Figure 1. Soil CO₂ emission variations between organic amendment (chicken manure and bone meal) types based on the results of the Tukey's HSD post hoc statistical test. Organic amendemnts not sharing the same letter are significantly different at P < 0.05.

Figure 2. Comparison of soil CO₂ emissions between OA rates based on the results of the Tukey HSD post hoc statistical test. Application rates not sharing the same letter are significantly different at P < 0.05.

Figure 3. Interaction effects of organic amendment type and rate on soil CO₂ emissions based on the results of the Tukey HSD post hoc statistical test. Application rates not sharing the same letter are significantly different at P < 0.05.

Figure 4. Cumulative soil CO₂ flux between organic amendemnt rates (a) and between irrigation levels (b).

Figure 5. Daily ambiant air minimum (T_min) and maximum (T_max) temperatures and rainfall records at the Waimanalo Research Station.

Table 5. Analysis of variance results of soil moisture content as a function of irrigation level (IRR), organic amendment type (OA) and rate.

Source	df	SS	MS	F	P-value
IRR	2	1513	756.4	1.7	0.184
OA	1	271	271.02	0.61	0.4359
Rate	3	4120	1373.32	3.08	0.0268
IRR × OA	2	434	217.24	0.49	0.6146
IRR × Rate	6	4896	816.02	1.83	0.0904
OA × Rate	3	1465	488.45	1.1	0.3503
IRR × OA × Rate	6	1677	279.43	0.63	0.7092
Error	915	408128	446.04
Total	940

Figure 6. Effects of OA rates on average soil moisture content based on the results of the Tukey's HSD post hoc statistical test. Application rates not sharing the same letter are significantly different at P < 0.05.

Figure 7. Correlation between soil moisture content and CO₂ flux by organic amendment type.

Table 6. Analysis of variance results of soil organic matter as a function of irrigation level (IRR), organic amendment type (OA) and rate.

Source	df	SS	MS	F	P-value
IRR	2	2.13	1.07	1.40	0.26
OA	1	0.17	0.17	0.22	0.64
Rate	3	7.40	2.47	3.25	0.03
IRR × OA	2	0.50	0.25	0.33	0.72
RR × Rate	6	3.93	0.65	0.86	0.53
OA × Rate	3	1.20	0.40	0.53	0.67
IRR × OA × Rate	6	4.71	0.78	1.03	0.42
Error	46	34.96	0.76
Total	71	58.54

Figure 8. Comparison of soil organic matter content between soils amended with different OA rates based on the results of the Tukey's HSD post hoc statistical test. Application rates not sharing the same letter are significantly different at P < 0.05.

USDA. Soil Survey of Islands of Kauai, Oahu, Maui, Molokai, and Lanai, State of Hawaii; USDA-SCS: Washington, DC, 1972, 1972.

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