4 RESULTS
4.4 Gross-Gerau 2004
4.4.2 NIRS analysis results
Table 4.33: Maize crude fibre contents according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 23,4 18,5 17,3 15,9
KX2352 24,5 18,9 17,3 15,3
Vitalina 26,2 19,7 17,6 15,9
Doge 27,3 20,5 18,9 17,0
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,3 0,3 0,5
The highest CF content (27,3 %) was found in Doge at par with Vitalina (26,2 %) when they were both harvested at the second harvest time. The lowest (15,3 %) was measured in KX2352 when it was harvested at the fourth harvest time.
Maize neutral detergent fibres (NDF)
As shown in table 4.34 below, delaying harvest decreased maize’s NDF of all cultivars in the same pattern as it did to CF. Hence NDF of all the cultivars decreased with each delay in harvest. NDF values of the cultivars were very similar across harvest times and seemed to depend on maturity class. There was also a significant interaction (LSD = 0,3) between cultivar and harvest time.
Table 4.34: Maize neutral detergent fibres content according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 51,7 41,3 39,3 37,4
KX2352 54,3 41,8 39,5 36,7
Vitalina 56,1 42,5 39,9 37,7
Doge 57,8 44,8 41,9 39,3
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,4 0,4 0,3
The highest NDF content (57,8 %) were measured in Doge when it was harvested at the first harvest time and the lowest (36,7 %) was measured in KX2352 at the fourth harvest time.
Maize acid detergent fibres (ADF)
Table 4.35 shows ADF of all cultivars to also have decreased with every delay in harvest for all cultivars in the same pattern as did CF and NDF.A significant interaction (LSD = 0,7) between cultivar and harvest time was also observed. Doge produced the highest (33,0%) ADF at the first harvest time and the lowest ADF was measured in KX2352 (19,2 %) at the fourth harvest time.
Table 4.35: Maize acid detergent fibres content according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 27,8 22,4 20,8 19,9
KX2352 29,3 22,8 21,0 19,2
Vitalina 31,6 23,3 21,4 19,8
Doge 33,0 24,8 22,9 21,1
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,3 0,3 0,7
The lowest ADF was measured in KX2352 (19,2 %) at the fourth harvest time. Like NDF, ADF values of the cultivars were similar across harvest times and in the range observed by Thomas et al. (2001).
Maize in vitro digestibility (ELOS)
Maize ELOS increased with delay in harvest for all the cultivars as can be seen in table 4.36. A significant interaction between cultivar and harvest time was observed.
The most significant increase for each cultivar was from the first harvest to the second. While KX2352 produced the highest (74,1 %) ELOS at the fourth harvest, Doge produced the lowest (58,8 %) when harvested at the first harvest time.
Table 4.36: Maize enzyme soluble organic substances according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 63,3 70,5 71,8 73,2
KX2352 62,7 70,2 71,7 74,1
Vitalina 60,5 69,8 71,3 73,3
Doge 58,8 68,1 69,8 71,9
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,4 0,4 0,7
While KX2352 produced the highest (74,1%) ELOS at the fourth harvest, Doge produced the lowest (58,8%) when harvested at the first harvest time. Increasing digestibility with advancing maize maturity has been reported by Bal et al. (1997) and attributed to increasing grain ratio in whole plant maize silage.
Maize sugar content
From table 4.37 every delay in harvest can be observed to decrease the sugar contents of maize cultivars. KXA2352 (16,9%) produced the highest sugar content at par with Vitalina (16,8 %) when both were harvested at the first harvest time.
Table 4.37: Maize sugar content according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 14,2 10,5 7,1 6,1
KX2352 16,9 10,7 7,3 5,9
Vitalina 16,8 11,0 7,6 5,9
Doge 16,1 11,9 8,8 6,5
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,2 0,2 0,3
The lowest sugar content (5,9 %) was produced also by KX2352 and Vitalina at par with Gavott when they were harvested at the fourth harvest time. A significant interaction (LSD = 0,3) between cultivar and harvest time occurred .
Maize starch contents
Table 4.38 shows maize starch contents increasing with every delay in harvest for each cultivar. Despite the observed different rates of increases among the cultivars, the most significant increase for each cultivar was from the first harvest to the second.
Table 4.38: Maize starch content according to cultivar and harvest time, Gross-Gerau 2004
Cultivar(CV) Harvest time (HT)
1 2 3 4
Gavott 14,1 29,9 37,7 41,9
KX2352 8,2 29,0 37,4 43,4
Vitalina 6,3 27,9 36,5 42,6
Doge 5,6 24,4 32,6 39,6
CV HT CV*HT
p - value 0,000 0,000 0,000
LSD (5%) 0,6 0,6 1,2
KX2352 produced the highest starch content (43,4 %) at par with Vitalina(42,6 %) when both were harvested at the fourth harvest time. The lowest starch content (5,6 %) was measured in Doge at par with Vitalina (6,3 %) when they were harvested at the first harvest time. A significant interaction (LSD = 1,2) between cultivar and harvest time was observed .
Maize organic matter content
By comparing the dry matter yields and the volatile solids (VS) yields of all the maize cultivars presented in table 4.39, their differences can be observed to be significantly small. In terms of anaerobic digestion this suggests whole plant maize silages rich in organic matter. Digestibility which depends on this organic matter is influenced by the degree of lignification of this organic portion of the dry matter.
In the experiments and laboratory analysis reports of Giessen, biogas productivity dynamics within the twenty one days retention time has been shown to depend on the ratio of cell contents and cell wall contents. Examples of these dynamics have been illustrated (figures 4.18 to 4.23 ) below for Gavott (S 250), Atletico (S 280) and Fiacre (S 350).
262
433
538
619
141
240
304 355
678
170
395
90 0
100 200 300 400 500 600 700 800
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Retention time (Days) Specific Gas / methane productivity (nL /kgVS)
Biogas sum curve nl/kg VS Methane sum curve nL/kg VS
Fig. 4.18: Cumulative curves of biogas and methane yields of Doge (FAO 700) grown in Gross-Gerau and harvested at the and first harvest time in 2004
0 100 200 300 400 500 600 700 800
0 2 4 6 8 10 12 14 16 18 20 22
Tage Gassummenkurve [l n/kg oTS]
Doge ET-1_GG-04 Doge ET-3_GG-04 Doge ET-4_GG-04
Fig. 4.19: Cumulative curves of biogas yields of Doge (FAO 700) according to retention time at the first, third and fourth harvest times. ET-1-First harvest, ET-3-third harvest time, ET-4-Fourth harvest time ; oTS-Volatile
0 50 100 150 200 250 300 350 400 450
0 2 4 6 8 10 12 14 16 18 20 22
Tage Methansummenkurve [l n CH4/kg oTS]
Doge ET-1_GG-05 Doge ET-3_GG-05 Doge ET-4_GG-05
Fig. 4.20: Cumulative curves of methane yields of Doge(FAO 700) according to retention time at the first, third and fourth harvest times. ET-1-First harvest, ET-3-third harvest time, ET-4-Fourth harvest time ; oTS-Volatile solids, GG-Gross-Gerau 2004
361
502
583
651
712
133 192
274 322 363 402
253
0 111,2 222,4 333,6 444,8 556 667,2 778,4
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Retention time (Days) Specific Gas/methane productivity (nL/kg VS)
Biogas sum curve nl/kg VS Methane sum curve nL/kg VS
Fig 4.21: Cumulative curves of biogas and methane yields of Gavott (S 250) grown in Gross-Gerau and harvested at the and first harvest time in 2004
0 100 200 300 400 500 600 700 800
0,00 2,00 4,00 6,00 8,00 10,00 12,00 14,00 16,00 18,00 20,00 22,00
Tage Gassummenkurve [l n/kg oTS]
Gavott ET-1_GG-04 Gavott ET-3_GG-04 Gavott ET-4_GG-04
Fig. 4.22: Cumulative curves of biogas yields of Gavott (S 250) according to retention time at the first, third and fourth harvest times. ET-1-First harvest, ET-3-third harvest time, ET-4-Fourth harvest time ; oTS-Volatile solids, GG-Gross-Gerau 2004
0 50 100 150 200 250 300 350 400 450
0 2 4 6 8 10 12 14 16 18 20 22
Tage Methansummenkurve [l n CH4/kg oTS]
Gavott ET-1_GG-05 Gavott ET-3_GG-05 Gavott ET-4_GG-05
Fig 4.23: Cumulative curves of methane yields of Gavott (S 250) according to retention time at the first, third and fourth harvest times. ET-1-First harvest, ET-3-third harvest time, ET-4-Fourth harvest time ; oTS-Volatile solids, GG-Gross-Gerau 2004
Maize biogas and methane productivity
Table 4.39 and fig 4.24 below show delaying harvest to lead to decrease in biogas productivity of both Gavott and Doge. Gavott (S 250) produced higher specific biogas volumes at the first harvest compared to Doge (FAO 700). From third to fourth
in agreement with Oechsner et al. (2003) who observed early cultivars to produce more biogas at the early harvest times than late cultivars but with the late cultivars outperforming the early ones at later harvest times. The rate of decrease in biogas productivity can therefore be seen (fig 4.244) to be faster in Gavott than in Doge.
712
642 588
678 651 622
402 348
308
395 371
335
0 111,2 222,4 333,6 444,8 556 667,2 778,4
1 3 4 1 3 4
Gavott Doge
Cultivar and harvest time specific Gas /methane productivity (nL/kg VS)
Gas nL /kg VS CH4 nL /kg VS
Fig. 4.24: Maize biogas and methane productivity according to cultivar and harvest time, Gross-Gerau 2004
Table 4.39 and fig 4.24 also show methane productivity of Gavott and Doge to decrease with each delay in harvest. The rates of decreases in both cultivars can be seen to follow the same pattern as did their biogases. Gavott (S 250) also produced higher specific methane volumes at the first harvest than Doge. From third to the fourth harvest. Doge can be observed to outperform Gavott in specific methane volume productivity in the same manner as was observed for biogas productivity.