9.4 Case Study of PGPR (LOB) Application in Fields
9.4.1 Sorghum Case
Sorghum is a cereal crop, and its grain is used as a staple food in several forms of
food product, cooked or fermented food, which are undoubtedly a nutrient-rich food
source. Sorghum plant stems can be squeezed juice to be fermented into ethanol.
Sorghum plants are suitable to be cultivated in a rather dry land and dry climate. In
such an environment, PGPR has an important role to support in providing nutrition
and to further enhance plant resistance to drought stress. Conversely, PGPR treatments can also reduce inorganic chemical fertilization and pesticide spraying.
Sorghum plants were treated with: (1) 100% inorganic fertilizer, (2) LOB-BS,
(3) LOB-BS + 50% inorganic fertilizer, (4) LOB-BS + 100% inorganic fertilizer.
Compost (20 ton/ha) as a basic fertilizer was also applied to each treatment.
Furthermore, 7 L/ha LOB-BS was applied 3 times more. When sorghum was treated
with LOB-BS and 50% inorganic chemical fertilizer, its yield was almost the same as
the 100% inorganic fertilizer application; however, its sugar Brix value was higher
than that of 100% inorganic fertilizer application treatment (Fig. 9.3) (Agustiyani
et al. 2015a, b).
9.4.2 Rice Case
Rice is the most important food crop in Indonesia, for which a large amount of
inorganic synthetic chemical fertilizers is conventionally applied in cultivation.
When PGPR biological fertilizers (LOB-BS) were used, the application rate of
inorganic synthetic chemical fertilizers can reduce around 30–50% in various areas
of lowland rice and upland rice farming; however, rice grain yield increased around
15–25%. The conventional standard fertilizer application rate for rice is 300 kg/ha
(N-P-K: 15-15-15), plus 200 kg/ha urea, which can reduce 30% by LOB-BS
treatment (7 L/ha for 3 times). When LOB-BS treatment was applied, the flag leaves
were still green to harvest, indicating a high photosynthetic rate is maintained until
the harvest (Fig. 9.4). Thus, very high yields with LOB-BS treatment achieved
11 tons/ha, compared with control (8 tons/ha). When applied to local rice, the
grain yield did not respond to LOB-BS treatment appropriately; however, the yield
can increase by up to 20% in some cases. Overall, applying an environment-friendly
technology with LOB-BS treatment, rice growth and productivity can be improved,
whereas the chemical fertilizer application rate can be reduced.
9 Plant Growth-Promoting Rhizobacteria (PGPR) and Compost Materials for. . .
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9.4.1 Sorghum Case
Sorghum is a cereal crop, and its grain is used as a staple food in several forms of
food product, cooked or fermented food, which are undoubtedly a nutrient-rich food
source. Sorghum plant stems can be squeezed juice to be fermented into ethanol.
Sorghum plants are suitable to be cultivated in a rather dry land and dry climate. In
such an environment, PGPR has an important role to support in providing nutrition
and to further enhance plant resistance to drought stress. Conversely, PGPR treatments can also reduce inorganic chemical fertilization and pesticide spraying.
Sorghum plants were treated with: (1) 100% inorganic fertilizer, (2) LOB-BS,
(3) LOB-BS + 50% inorganic fertilizer, (4) LOB-BS + 100% inorganic fertilizer.
Compost (20 ton/ha) as a basic fertilizer was also applied to each treatment.
Furthermore, 7 L/ha LOB-BS was applied 3 times more. When sorghum was treated
with LOB-BS and 50% inorganic chemical fertilizer, its yield was almost the same as
the 100% inorganic fertilizer application; however, its sugar Brix value was higher
than that of 100% inorganic fertilizer application treatment (Fig. 9.3) (Agustiyani
et al. 2015a, b).
9.4.2 Rice Case
Rice is the most important food crop in Indonesia, for which a large amount of
inorganic synthetic chemical fertilizers is conventionally applied in cultivation.
When PGPR biological fertilizers (LOB-BS) were used, the application rate of
inorganic synthetic chemical fertilizers can reduce around 30–50% in various areas
of lowland rice and upland rice farming; however, rice grain yield increased around
15–25%. The conventional standard fertilizer application rate for rice is 300 kg/ha
(N-P-K: 15-15-15), plus 200 kg/ha urea, which can reduce 30% by LOB-BS
treatment (7 L/ha for 3 times). When LOB-BS treatment was applied, the flag leaves
were still green to harvest, indicating a high photosynthetic rate is maintained until
the harvest (Fig. 9.4). Thus, very high yields with LOB-BS treatment achieved
11 tons/ha, compared with control (8 tons/ha). When applied to local rice, the
grain yield did not respond to LOB-BS treatment appropriately; however, the yield
can increase by up to 20% in some cases. Overall, applying an environment-friendly
technology with LOB-BS treatment, rice growth and productivity can be improved,
whereas the chemical fertilizer application rate can be reduced.
9 Plant Growth-Promoting Rhizobacteria (PGPR) and Compost Materials for. . .
313