Practical considerations of moisture in baled biomass feedstocks

Figures & data

Figure 1.  Diagram of coring locations used for both square and round bales.

(A) Rectangular bales: nine-core pattern; (B) Rectangular bales: 14-core pattern; (C) Round bales: 12-core pattern.

Figure 2.  Moisture isopleths calculation.

Spatial dependence of individual moisture concentrations at specific locations was interpolated to estimate moisture concentrations along multiple paths.

Figure 3.  Effect of tarping on moisture distribution in corn stover bales.

(A) Tarped corn stover and (B) open corn stover. Both average 22.2.% wet basis. Moisture content is indicated by the bar under the maps and ranges from approximately 5 to 65%. Scale is shown in feet as the sample locations were based on intervals of the same unit.

Histograms show moisture distributions as calculated by interpolation.

Figure 4.  Effect of precipitation on moisture distribution in corn stover bales.

(A) Tarped corn stover under wet conditions, average 23.2% wet basis; and (B) tarped corn stover under dry conditions, average 16.5% wet basis. Relative moisture content is indicated by the bar under the maps and ranges from approximately 10 to 60%.

Histograms show moisture distributions as calculated by interpolation.

Figure 5.  Effect of wrapping on moisture distribution over time.

Wrapped low moisture sorghum bales after (A) 3 months of storage, average 19.1% wet basis; (B) 9 months of storage, average 23.1% wet basis; and (C) 12 months of storage, average 22.4% wet basis.

Relative moisture content is indicated by the bar under the maps and ranges from approximately 10 to 60%.

Figure 6.  Moisture distribution in round corn stover bales at 5 months storage.

(A) 35.5% wet basis; (B) 41% wet basis; and (C) 51.2% wet basis. Relative moisture content is indicated by the bar over the maps and ranges from approximately 25 to 75%.

Table 1.  Bale and stack conditions showing initial moisture contents for the feedstock at different storage locations.

Stack identifier	Treatment	Bale type	Stack configuration^†	Number of sample bales	Initial moisture (% wb)^‡
Northwest Iowa
HM-T	Tarped	3 × 4 ft (1.2 × 1.2 m) rectangular	1 × 4	24	33.3 (3.4)
IM-T	Tarped	4 × 4 ft (0.9 × 1.2 m) rectangular	1 × 3	9	25.6 (3.1)
LM-T	Tarped	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	12	14.5 (1.5)
LM-W	Plastic wrap	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 3	27	11.3 (1.5)
LM-O	Open/none	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	12	13.9 (3.5)
RndPyr-T	Tarped	6 ft (1.8 m) round	3 × 3 pyramid	18	10.2 (1.7)
RndPyr-O	Open/none	6 ft (1.8 m) round	3 × 3 pyramid	18	10.5 (1.1)
RndLine-O	Open/none	6 ft (1.8 m) round	1 × 0	8	12.8 (2.4)
East central Texas
HM-T	Tarped	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	16	31.5 (5.6)
LM-T	Tarped	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	16	20.3 (4.4)
HM-W	Plastic wrap	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 3	12	31.5 (5.6)
LM-W	Plastic wrap	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 3	12	20.3 (4.4)
Central Iowa
IM-T stack A	Tarped	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	32	21.9 (2.2)
IM-T stack B	Tarped	3 × 4 ft (0.9 × 1.2 m) rectangular	1 × 4	32	19.1 (1.7)

^†Storage configuration dimensions represented as number of bales wide by number bales high.

^‡Mean values for all initial cores collected. Standard deviation is presented in parenthesis.

HM: High moisture; IM: Intermediate moisture; LM: Low moisture; O: Open; RndLine: Single round bale lines; RndPyr: Round bale stack; T: Tarped; wb: Wet basis; W: Wrapped.

Table 2.  Moisture contents for stored feedstock and their changes over time.

Stack identifier	Treatment	Initial moisture (% wb)^†	3 months storage^†			5 months storage^†			9 months storage^†
			Final moisture (% wb)	Change (% wb)		Final moisture (% wb)	Change (% wb)		Final moisture (% wb)	Change (% wb)
Northwest Iowa
HM-T	Tarped	33.3 (3.4)	29.7 (3.8)	-3.6		27.5 (5.6)	-5.7		21.1 (2.4)	-12.1
IM-T	Tarped	25.6 (3.1)	27.2	1.6		23.2	-2.4		22.5	-3.1
LM-T	Tarped	14.5 (1.5)	24.6	10.1		18.2	3.7		22.2	7.7
LM-W	Plastic wrap	11.3 (1.5)	17.5 (0.6)	6.1		14.3 (0.9)	3.0		12.0 (0.9)	0.7
LM-O	Open/none	13.9 (3.5)	23.9	9.9		22.2	8.2		20.6^‡	6.7
RndPyr-T	Tarped	10.2 (1.7)	24.8 (2.1)	14.6		21.2 (4.2)^†	10.9		15.4 (3.1) ^‡	5.2
RndPyr-O	Open/none	10.5 (1.1)	34.7 (7.6)	24.2		32.6 (8.8)	22.1		37.0 (4.1)	26.5
RndLine-O	Open/none	12.8 (2.4)	NA	NA		42.8 (9.6)	29.9		40.2 (2.3)	27.4
			3 months storage			9 months storage			12 months storage
East central Texas
HM-T	Tarped	31.5 (5.6)	18.8	-12.7		18.0	-13.5		13.7	-17.8
LM-T	Tarped	20.3 (4.4)	16.0	-4.3		17.0	-3.3		14.0	-6.3
HM-W	Plastic wrap	31.5 (5.6)	28.8	-2.7		28.6	-3.0		20.1	-11.4
LM-W	Plastic wrap	20.3 (4.4)	19.1	-1.3		23.1	2.8		22.4	2.1
			4 months storage			7 months storage
Central Iowa
IM-T stack A	Tarped	21.9 (2.2)	18.5 (0.7)	-3.4		16.3 (0.4)	-5.6		NA	NA
IM-T stack B	Tarped	19.1 (1.7)	17.6 (0.9)	-1.5		15.3 (0.8)	-3.8		NA	NA

^†Mean values presented for stacks with replicate sampling units. Standard deviation between replicates is presented in parenthesis when available.

^‡One or more bales were destroyed during handling at the time of removal, preventing a final bale mass from being recorded.

HM: High moisture; IM: Intermediate moisture; LM: Low moisture; NA: Not applicable; O: Open; RndLine: Single round bale lines; RndPyr: Round bale stack; T: Tarped; wb: Wet basis; W: Wrapped.

Table 3.  Dry matter loss for stored feedstock over time.

Stack identifier	Treatment	3 months storage			5 months storage			9 months storage
		DML (%)	95% CI (%)		DML (%)	95% CI (%)		DML (%)	95% CI (%)
Northwest Iowa
HM-T	Tarped	13.9	3.5		12.2	0.2		7.7	3.1
IM-T	Tarped	14.4	NA		6.0	NA		1.2	NA
LM-T	Tarped	12.6	NA		3.3	NA		6.4	NA
LM-W	Plastic wrap	5.8	21.5		13.5	4.2		-13.4	4.9
LM-O	Open/none	2.8	NA		-2.6	NA		-0.2	NA
RndPyr-T	Tarped	28.7	10.4		9.9^†	4.0		2.0^†	10.7
RndPyr-O	Open/none	21.2	9.0		10.5	37.0		7.0	10.5
RndLine-O	Open/none	NA	NA		22.4	29.5		8.7	10.2
		3 months storage			9 months storage			12 months storage
East central Texas
HM-T	Tarped	15.5	NA		28.5	NA		19.0	NA
LM-T	Tarped	23.0	NA		30.9	NA		24.8	NA
HM-W	Plastic wrap	12.3	NA		18.4	NA		44.8	NA
LM-W	Plastic wrap	18.8	NA		30.0	NA		24.9	NA
		4 months storage			7 months storage
Central Iowa
IM-T stack A	Tarped	6.3	3.9		4.5	4.5		NA	NA
IM-T stack B	Tarped	8.3	5.9		6.6	2.5		NA	NA

^†One or more bales were destroyed during handling at the time of removal, preventing a final bale mass from being recorded.

CI: Confidence interval; DML: Dry matter loss; HM: High moisture; IM: Intermediate moisture; LM: Low moisture; NA: Not applicable; O: Open; RndLine: Single round bale lines; RndPyr: Round bale stack; T: Tarped; W: Wrapped.