1. Fig 1: Nitrogen fertilizer application at V7.
Ethanol Yields as Affected by Nitrogen Fertilizer Rate in Sweet and Photoperiod Sensitive Forage Sorghums. Parikshya Lama Tamang, Kevin Bronson, Adi Malapati, and Robert Schwartz Texas A&M AgriLife Research, Texas Tech Univ., Lubbock, TX, and USDA-ARS, Bushland, TX
Abstract
Table 3. Ethanol from juice as affected by cultivar and N fertilizer rate, Lubbock, 2008 and 2009.
Sorghum (Sorghum bicolor L) grown in the Texas High Plains is mainly grain sorghum and the balance is forage sorghums. In this region, there is little information available on N fertilizer requirements for the ethanol production from these sorghums. This study was conducted in 2008 and 2009 on an Acuff sandy clay loam at Texas A&M AgriLife Research and Extension center farm near Lubbock. The total dry matter (TDM), total N uptake, juice yields, juice ethanol, cellulosic ethanol and total ethanol yields were higher in 2009 than in In 2009, TDM was in higher forage sorghum than in sweet sorghum cultivars. In 2008 N application did not increase juice ethanol yields, but in 2009, cultivar M81E showed N response. As expected, cellulosic ethanol yield was higher in forage sorghum cultivars than sweet sorghum cultivars in In 2009, sweet sorghum cultivars, especially M81E, had the highest total ethanol yield than the forage sorghum cultivars. The optimum N fertilizer rate for ethanol and TDM across all four sorghums was 107 kg ha-1 and 108 kg ha-1 respectively in 2009.
2008
Cultivar
N rate
Della
M81E
Means
kg ha L ha
984
569
777 a 67
902
1013
957 a
101
998
527
763 a
134
1041
1442
1242 a
168
1178
608
893 a
1021 A
832 A
2009
1418a
1118c
1268
1486a
1651ab
1568
1341a
1858a
1600
1294a
1471bc
1383
1717ab
1506
1366
1563
Fig 3. Fermentation of Sweet Sorghum Juice with the help of yeast.
Objectives
To compare ethanol yield from sweet sorghum and photoperiod sensitive forage sorghum with limited irrigation in the Texas High Plains.
To determine optimal Nitrogen fertilizer needs for ethanol production from sweet sorghum and photoperiod sensitive forage sorghum with limited irrigation in the Texas high plains.
Materials and Methods
Experimental design: Randomized complete block design with three replications.
N treatments: , 67, 101,134 and 168 N kg ha-1 (sidedressed as UAN at V7, Fig. 1)
Sorghum Varieties: Della, M81E (Sweet sorghums), Maxigain and Sugar
graze ultra (Photoperiod sensitive forage sorghums).
Planting Date: May , May
Canopy spectral reflectance measurements taken in mid July.
Harvesting Date: mid-September and 2009 (Fig. 2).
Data collected: Initial soil test nitrate, total dry matter, total N uptake,
biomass yield, juice, brix, juice ethanol, cellulosic ethanol, and
total ethanol.
Ethanol yield was estimated from fermented sweet sorghum juice (Fig. 3) and the biomass. Ethanol yield from forage sorghum and sweet sorghum bagasse was calculated from the analysis of Neutral detergent fiber (NDF) and NDF digestibility.
*Means with same alphabets are not significantly different from each other at P=0.05
Table 4. Cellulosic ethanol yield as affected by cultivar and N fertilizer rate, Lubbock, 2008 and 2009.
2008
Cultivar
N rate
Maxigain
Sugar graze ultra
Della
M81E
Means
kg ha-1
L ha
1293
1153
997
741
1046 a 67
1550
1104
879
884
1104 a
101
1479
1265
833
796
1093 a
134
1189
1432
813
812
1062 a
168
1397
995
983
1007
1096 a
1382 A
1190 A
901 A
848 A
2009
1191
1398
546
1098
1058 b
1556
2159
971
1391
1519 a
1892
1899
846
1485
1530 a
2047
1798
874
1308
1507 a
1769
1493
1092
1409
1441 a
1691 A
1749 A
866 C
1338 B
Fig 4. Pre-plant soil NO3-N content by depth, Lubbock, 2008.
Results and Discussions
In 2008, pre-plant soil NO3-N was high in all plots. In the surface 0.15 m and m soil profile, all plots averaged 30 and 65 kg NO3-N ha-1 respectively (Fig 3). In 2009, the residual soil NO3-N at depth was greater with the 134 and 168 kg N ha-1 fertilizer rates. In 2008, no cultivar response, N rate response and no cultivar X N rate interaction was noted in TDM. Total dry matter increased in 2009 compared to 2008 for all the cultivars except Della. In 2009, cultivar differences and N rate response was found in TDM, but no cultivar X N rate interaction (Table 1). M81E produced TDM of 13,524 kg ha-1 in 2009, much less than the report of Wu et al.,(2009) who reported that M81E TDM yields of 18, ,000 kg ha-1 in Kansas in Total N uptake was higher in 2008 than in 2009 i.e. 169 kg N ha-1 vs. 99 kg N ha-1 ( Table 2). This was probably due to high 2008 spring pre-plant NO3. Nitrogen uptake was higher in forage sorghum cultivars across N treatments than sweet sorghum cultivars in both years. Total N uptake responded to N fertilizer rate across the four cultivars in 2009, but not in 2008 (Table 2).
*Means with same alphabets are not significantly different from each other at P=0.05
Table 5.Total ethanol yield as affected by cultivar and N fertilizer rate, Lubbock, 2008 and 2009.
2008
Cultivar
N rate
Maxigain
Sugar graze ultra
Della
M81E
Means
kg ha-1
L ha
1293
1153
1982
1301
1434 a 67
1550
1104
1781
1897
1583 a
101
1479
1265
1831
1324
1475 a
134
1189
1432
1855
2073
1637 a
168
1397
995
2161
1783
1584 a
1382 A
1190 A
1922 A
1677 A
2009
1191
1398
1964
2216
1692 b
1556
2159
2457
3042
2304 a
1892
1899
2187
3343
2330 a
2047
1798
2168
2780
2198 a
1769
1493
2386
3127
2194 a
1691 C
1749 C
2232 B
2902 A
Fig 5. Pre-plant soil NO3-N Content by Depth as Affected by N Fertilizer rate Lubbock, 2009.
Table 1. Total Dry Matter as affected by cultivar and N fertilizer rate, Lubbock, 2008 and 2009.
2008
Cultivar
N rate
Maxigain
Sugar graze ultra
Della
M81E
Means
kg ha
14011
12330
10487
8033
11215 a 67
17374
12143
10024
9527
12267 a
101
16626
13451
91378
8406
11905 a
134
13077
15692
10415
9519
12176 a
168
10835
11414
11236
12294 a
15356 A
12890 A
10296 A
9344 A
2009
11790
13639
6919
11289
10909 b
15728
19255
10979
14091
15013 a
17932
17443
10215
15111
15175 a
19974
16128
10329
13013
14861 a
17174
13645
11590
14114
14131 a
16520 A
16022 A
10006 C
13524 B
Fig 1: Nitrogen fertilizer application at V7.
* Means with same alphabets are not significantly different from each other at P=0.05.
Juice ethanol yields had no treatment effects in Ethanol from juice yields were higher in 2009 than in Juice ethanol responded positively to N rate only in the case of M81E and only in 2009 (Table 3). Cellulosic ethanol yields did not respond to cultivar or N in 2008 (Table 4). Forage sorghums had greater cellulosic ethanol yields than the sweet sorghums in Cellulosic and total ethanol yields responded to N rate in all sorghum cultivars in 2009 (Table 4). However, M81E had the greatest total ethanol yield in 2009, followed by Della. Forage sorghums had the lowest total ethanol yields in Regressions (not shown) of the 2009 TDM and total ethanol yields vs. N rate indicated that the optimum N rate was 108 kg N ha-1, regardless of sweet or forage sorghum cultivar. This compares well with the optimum N rate of 112 kg ha-1 reported for sweet sorghum in Georgia by Gascho et al., (1984).
Conclusion
Dry matter, juice, or ethanol yields did not respond to N fertilizer in This was probably due to the pre-plant soil NO3-N, which averaged 140 kg NO3-N ha-1 for the m soil profile.
Total N uptake was higher in all cultivars in 2008 than in 2009, i.e. 169 kg N ha-1 vs. 99 kg N ha-1 presumably due to the luxury N uptake of high soil profile NO3-N content in 2008.
Juice ethanol yields responded positively to N rate only in case of M81E and only in 2009.
Cellulosic ethanol yields were higher in photoperiod sensitive forage sorghum cultivars compared to sweet sorghum cultivars in 2009
Total ethanol yields were higher in 2009 than in 2008 i.e L ha-1 and 1543 L ha-1 respectively.
Total ethanol yields were less with photoperiod sensitive forage sorghum cultivars than with sweet sorghum cultivars in 2009.
Among the cultivars, M81E had the highest total ethanol yield of 2902 L ha-1, and the control plots had the lowest total ethanol yield across the cultivars.
The optimum N fertilizer rate for ethanol and TDM across all four sorghums was 108 kg N ha-1 in 2009.
* Means with same alphabets are not significantly different from each other at P= 0.05
Table 2. Total N uptake as affected by Cultivar and N fertilizer rate, Lubbock, 2008 and 2009.
2008
Cultivar
N rate
Maxigain
Sugar graze ultra
Della
M81E
Means
kg ha
183
200 92 78
138 a 67
289
228 88 79
171 a
101
325
232
105 81
186 a
134
225
214
111
102
163 a
168
301
175
126
129
183 a
26 A
210 A
105 B
94 B
2009 93 45 61
66 b
108
130 65 84
97 a
135 68 99
108 a
149
139 75 82
111 a
154
124 76 91
123 A
66 B
83 B
References
Gascho, G.J., R.L. Nichols, and T.P. Gaines Growing sweet sorghum as a source of fermentable sugars for energy. Research Bulletin, 315, University of Georgia, Athens, GA.
Xiaorong, Wu., S. Staggenborg, J.L. Propheter, W.L. Rooney, Y. Jianming, and D. Wang Features of sweet sorghum juice and their performance in ethanol fermentation. Industrial crops and products 31:
Fig 2. Sweet sorghum pressed under Mechanical Roller Press in order to obtain the juice.
* Means with same alphabets are not significantly different from each other at P=0.05.