Abstract
The demand for cassava tuber in Indonesia is high, however, domestic production is still limited therefore increasing production is important. Ultisol soils have the potential for cassava production, but low soil fertility in such soils needs to be improved. The research aimed to evaluate the effect of soil organic carbon (SOC) and NPK fertilizer on the growth and yield of cassava tuber in an ultisol. The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java from September 2022 to January 2023. The experiment used a split-plot design with three replications. The main plot was SOC level of 1.93 (control), 2, 3, and 4%, and the subplot was NPK 15-15-15 level of 150, 300, 450, and 600 kg ha-1. SOC level was increased through the application of cow manure 0, 3.59, 54.93, and 106.27 tons ha-1 corresponding to SOC levels of 1.93 (control), 2, 3, and 4%, respectively. Results showed that enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number. The leaf number was the highest in the 3% SOC+150 kg NPK, 2% SOC+300 kg NPK or+450 kg NPK, and control+600 kg ha-1 NPK treatment. Leaf greenness was only affected by adding NPK fertilizer; a high greenness value was obtained at NPK level of > 150 kg ha-1 and 300 to 600 kg ha-1 resulting in non-significantly leaf greenness. The status of N and K in the leaves increased by SOC and NPK treatments, while the P status was unaffected. SOC at a level of 3% and NPK at a level of 150 kg ha-1 stimulated cassava to produce the highest fresh tuber weight (1.85 kg per plant) at 4 months after planting. Cassava productivity in ultisol soil can be increased by applying cow manure of 54.93 tons ha-1 to enhance SOC up to 3% combined with NPK of 150 kg ha-1. Keywords: Extensification; food security; intensification; tuber production; nutrient uptake
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Claims 8
Claim · model-written summary
Enhancing SOC up to 3% and NPK 300 kg ha-1 was enough to support cassava growth in height, stem diameter and leaf number.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- enhancing SOC up to 3% and NPK 300 kg ha-1e1
- Outcome
- plant height, stem diameter, and leaf numbere1
- Qualifier
- were enough to support cassava growthe1
- Setting
- Jonggol Experimental Farme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
Claim · model-written summary
Leaf number of cassava was highest under the 3% SOC+150 kg NPK, 2% SOC+300 kg NPK or +450 kg NPK, and control+600 kg ha-1 NPK treatments.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- 3% SOC+150 kg NPK, 2% SOC+300 kg NPK or+450 kg NPK, and control+600 kg ha-1 NPKe2
- Outcome
- leaf numbere2
- Direction
- higheste2
- Setting
- Jonggol Experimental Farme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
e2“The leaf number was the highest in the 3% SOC+150 kg NPK, 2% SOC+300 kg NPK or+450 kg NPK, and control+600 kg ha-1 NPK treatment”
Claim · model-written summary
Leaf greenness of cassava was affected only by adding NPK fertilizer.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- adding NPK fertilizere3
- Outcome
- Leaf greennesse3
- Direction
- affectede3
- Setting
- Jonggol Experimental Farme0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
e3“Leaf greenness was only affected by adding NPK fertilizer”
Claim · model-written summary
Leaf greenness of cassava was high and not significantly different at NPK levels above 150 kg ha-1 and from 300 to 600 kg ha-1.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- NPK level of > 150 kg ha-1 and 300 to 600 kg ha-1e4
- Outcome
- leaf greennesse4
- Qualifier
- non-significantlye4
- Setting
- Jonggol Experimental Farme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
e4“a high greenness value was obtained at NPK level of > 150 kg ha-1 and 300 to 600 kg ha-1 resulting in non-significantly leaf greenness”
Claim · model-written summary
SOC and NPK treatments increased the N and K status of cassava leaves.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- SOC and NPK treatmentse5
- Outcome
- status of N and K in the leavese5
- Direction
- increasede5
- Setting
- Jonggol Experimental Farme0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
e5“The status of N and K in the leaves increased by SOC and NPK treatments, while the P status was unaffected”
Claim · model-written summary
SOC and NPK treatments did not affect the P status of cassava leaves.
- Taxon
- cassava
Manihot esculentae1 - Treatment
- SOC and NPK treatmentse5
- Outcome
- P statuse5
- Direction
- unaffectede5
- Setting
- Jonggol Experimental Farme0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e1“enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number”
e5“The status of N and K in the leaves increased by SOC and NPK treatments, while the P status was unaffected”
Claim · model-written summary
SOC at 3% with NPK at 150 kg ha-1 gave the highest fresh tuber weight of cassava (1.85 kg per plant) at 4 months after planting.
- Taxon
- cassava
Manihot esculentae6 - Treatment
- SOC at a level of 3% and NPK at a level of 150 kg ha-1e6
- Outcome
- fresh tuber weighte6
- Direction
- higheste6
- Value
- 1.85 kg per plante6
- Qualifier
- at 4 months after plantinge6
- Setting
- Jonggol Experimental Farme0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e6“SOC at a level of 3% and NPK at a level of 150 kg ha-1 stimulated cassava to produce the highest fresh tuber weight (1.85 kg per plant) at 4 months after planting”
Claim · model-written summary
Cassava productivity in ultisol can be increased by applying 54.93 tons ha-1 of cow manure to raise SOC to 3%, combined with 150 kg ha-1 NPK.
- Taxon
- Cassava
Manihot esculentae7 - Treatment
- applying cow manure of 54.93 tons ha-1 to enhance SOC up to 3% combined with NPK of 150 kg ha-1e7
- Outcome
- productivitye7
- Setting
- Jonggol Experimental Farme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java”
e7“Cassava productivity in ultisol soil can be increased by applying cow manure of 54.93 tons ha-1 to enhance SOC up to 3% combined with NPK of 150 kg ha-1”
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