Biochar-Poultry Manure Compost Alters Temperature and Nitrogen Dynamics during Composting and Improves Potato Growth Following Field Application

Figures & data

Table 1. Values, including analytical methods, for agronomic, physical, and chemical properties of biochar feedstock.

Property	Value	Method
pH	9.5	1:5 soil water suspension (International Organization of Standardization (ISO) 2005)
EC (mmhos cm^-1)	4.8	1:5 soil water suspension (He et al. 2012)
Total N (% dry wt.)	0.44	Dry combustion (Matejovic 1997)
Organic Carbon (% dry wt.)	78.4	Dry combustion (Matejovic 1997)
NO3-N (% dry wt.)	0.0002	KCL extraction/Cadmium-reduction (Dahnke 1990)
NH4-N (% dry wt.)	0.0028	KCL extraction/Exchangeable ammonium (Dahnke 1990)
C:N	177.0	Dry combustion(Matejovic 1997)
Volatile matter (% dry wt.)	10.1	ASTM D1762-84 (ASTM International (American Society of Testing and Materials) 2013)
Ash (% dry wt.)	3.7	ASTM D1762-84 (ASTM International (American Society of Testing and Materials) 2013)
Hydrogen/Carbon (H:C)	0.25	ASTM D4373-14 (ASTM International (American Society of Testing and Materials) 2014)
Surface area (m^2 g^-1)	533.2	ASTM D6556-19a (ASTM International (American Society of Testing and Materials) 2019)
Bulk density (g cm^-3)	0.21	TMECC 03.03 (Thompson et al. 2003b)

Table 2. Physical and chemical properties of chicken manure and wood shavings feedstocks.

	Feedstocks
Property	Chicken manure	Wood shavings
Bulk density (g cm^-3)	0.87	0.23
Moisture (%)	26	66
Solids (%)	74	34
pH	8.0	5.5
EC (dS m^-1)	20.5	0.5
Total C (% dry wt.)	24.0	54.2
Total N (% dry wt.)	2.56	0.16
NO3-N (% dry wt.)	0.0009	0.0009
NH4-N (% dry wt.)	0.659	0.0081
C:N	9.37	341

Table 3. Mean dry weights in kgs (± SD, n = 3) at beginning (day 0) and end (day 34) of composting for elements in each of three composting treatments (control, Biochar 20%, and Biochar 40%).

	Control		Biochar 20%		Biochar 40%
Element	Day 0^a	Day 34^b	Day 0	Day 34	Day 0	Day 34
Top cap	14.9 (0)	13.8 (0.45)	14.9 (0)	12.8 (0.39)	14.9 (0)	11.6 (3.56)
Compost	296 (18.8)	263 (15.9)	251 (6.8)	225 (10.2)	221 (9.8)	198 (3.7)
Plenum	6.43 (0)	6.89 (0.49)	6.43 (0)	7.3 (1.93)	18.9 (0)	5.71 (0.84)

^aInitial measurements were made the day the reactor was filled, May 21^st, 22^nd, and 23^rd.

^bEnd measurements were made on June 24^th and 25^th.

Table 4. Wet and dry application rates (Mg ha^-1) for each compost treatment (control compost, Biochar 20%, and Biochar 40%) at the low (7 Mg dry C ha^-1) and high (15 Mg dry C ha^-1) amendment rates.

	Control		Biochar 20%		Biochar 40%
Rate	Low	High	Low	High	Low	High
Wet Weight	53.9	116	46.0	98.7	45.0	96.5
Dry Weight	23.2	49.7	18.4	39.5	16.7	35.7

Table 5. Mean values for compost bulk density (BD) and moisture content (MC) for each of three treatments at three collection periods day 0, 13, and 34.

	Day 0		Day 13		Day 34
Treatment	BD (Mg m^-3)	MC (%)	BD (Mg m^-3)	MC (%)	BD (Mg m^-3)	MC (%)
Control	0.581a ^a	58.6	0.460	57.3	0.500	57.3a
Biochar 20%	0.533b	62.0	0.423	59	0.462	60.3ab
Biochar 40%	0.476c	64.0	0.414	61.7	0.443	63.0b

^aMean values within a variable (e.g., BD) and collection period (e.g., Day 0) followed by different letters are significantly different according to Tukey’s HSD test (p < 0.05).

Figure 1. Compost temperatures for each of three treatments at two depths, 40.6 (deep) and 81.3 cm (shallow) measured from the base. Panels (a) and (b), and (c) and (d), illustrate temperatures within the first five days and the remaining 29 days, respectively. Bars are standard error of the mean for daily mean temperature (n = 3).

Table 6. Mean values for compost chemical and nutrient properties in each of three treatments collected at days 0 (D0) and 34 (D34) of composting.

	Total C (%)		Total N (%)		C:N		pH		EC (dS m^-1)		NO3-N (mg kg^-1)		NH4-N (mg kg^-1)
Treatment	D0	D34	D0	D34	D0	D34	D0	D34	D0	D34	D0	D34	D0	D34
Control	35.9aa	30.2a	1.56	1.13	23.0a	26.8a	8.1	7.9	10.9	7.7b	9.0	1330a	6010	268
Biochar 20%	39.4a	38.0b	1.56	1.17	25.6ab	32.6ab	8.8	7.9	9.3	6.8a	8.3	1520a	4850	29.0
Biochar 40%	45.6b	42.3c	1.54	1.22	29.3b	34.8b	8.3	7.6	8.0	6.6a	9.0	1960b	4670	41.0

^aMeans within a variable (e.g., C:N) and day (e.g., D0) column followed by different letters are significantly different according to Tukey’s HSD test (p < 0.05).

Table 7. Mass (kgs) and percent change from day 0 to day 34 in total C, total N, NO₃-N, and NH₄-N in different composting elements (top cap, compost, plenum).

		Change in mass (kgs)				Percent change
Material	Treatment	Total C	Total N	NO3-N	NH4-N	Total C	Total N	NO3-N	NH4-N
Top Cap	Control	−1.58^a	0.063	0.008	0.030	−19.6	268	6180	2470
	Biochar 20%	−2.67	0.060	0.010	0.026	−33.2	256	7600	2140
	Biochar 40%	−2.66	0.053	0.005	0.026	−33.0	226	3650	2110
Compost	Control	−27.2	−1.64c	0.346	−1.72	−24.9	−35.6b	13,300	−95
	Biochar 20%	−13.4	−1.25b	0.339	−1.21	−13.3	−32.3a	19,000	−99
	Biochar 40%	−16.9	−1.03a	0.385	−1.030	−16.7	−29.9a	20,900	−99
Plenum	Control	−0.21	0.034a	0.005	0.001	−6.07	329a	9350	284
	Biochar 20%	0.18	0.027a	0.004	0.003	5.23	265 a	696	518
	Biochar 40%	−0.85	0.015b	0.002	0.001	−24.3	144b	3660	122

^aMeans within a variable column (e.g., Total C) and material rows (e.g., Compost) followed by different letters are significantly different according to Tukey’s HSD test (p < 0.05).

Figure 2. Nitrogen loss from the total initial mass, including biochar (a) and the non-biochar compost (b).

Table 8. Compost physical and chemical properties for each of three treatments after curing and immediately prior to amendment.

Treatment	Total C (%)	Total N (%)	NO3-N (mg kg^-1)	NH4-N (mg g^-1)	Moisture (%)
Control	25.1	1.34	26	104	59
Biochar 20%	30.1	1.52	1020	103	65
Biochar 40%	29.6	1.30	883	52	67

Table 9. Mean values for soil physical and chemical properties following amendment and one potato growing season.

Treatment	Bulk density (g cm^-3)	Total C (%)	Total N (%)	NO3-N (mg kg^-1)	NH4-N (mg kg^-1)
Control^a	1.91a^b	1.07	0.137a	230	19.2
LowComp	1.83ab	1.13	0.145ab	246	16.5
HighComp	1.79b	1.45	0.169b	273	21.8
LowBiochar 20%	1.86ab	1.17	0.156ab	300	22.5
HighBiochar 20%	1.84ab	1.26	0.168ab	312	19.6
LowBiochar 40%	1.85ab	1.28	0.163ab	376	17.9
HighBiochar 40%	1.82ab	1.23	0.174b	369	19.6

^aField treatments are as follows: control is the unamended control; LowComp and HighComp are control composts at low and high rates; LowBiochar 20% and HighBiochar 20% are biochar amended composts (20%) at low and high rates; LowBiochar 40% and HighBiochar 40% are biochar amended composts (40%) at low and high rates.

^bMeans within a variable column (e.g., Bulk density) followed by different letters are significantly different according to Tukey’s HSD test (p < 0.05).

Table 10. Mean values for potato plant biomass following amendment including above (leaves) and below ground (tuber) variables.

	Leaves	Tuber
Treatment	Weight (kg ha^-1)	Number (ha^-1)	Weight (Mg ha^-1)
Control^a	77.3^b	10,600	1.49a
LowComp	84.2	10,460	1.70ab
HighComp	100	10,740	1.89ab
LowBiochar 20%	97.1	9750	1.87ab
HighBiochar 20%	94.4	10,030	1.77ab
LowBiochar 40%	92.4	10,320	1.67ab
HighBiochar 40%	118	12,300	2.11b

^aField treatments are as follows: control is the unamended control; LowComp and HighComp are control composts at low and high rates; LowBiochar 20% and HighBiochar 20% are biochar amended composts (20%) at low and high rates; LowBiochar 40% and HighBiochar 40% are biochar amended composts (40%) at low and high rates.

^bMeans within a variable column (e.g., Weight) followed by different letters are significantly different according to Tukey’s HSD test (p < 0.05).

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Data Availability Statement

Data that support the findings of this study are available at zenodo.org with the identifier: http://doi.org/10.5281/zenodo.4763775.