Abstract
Information on fertilizer response in cassava in Africa is scarce. We conducted a series of on-farm and on-station trials in two consecutive years to quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda and to evaluate factors governing the responses. Average unfertilized yields ranged from 4.2 to 25.7 t ha −1 between sites and years. Mineral fertilizer use increased yields significantly, but response to fertilizer was highly variable (−0.2 to 15.3 t ha −1 ). Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005. Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age. Relative N and K yields were positively correlated to SOC and exchangeable K, while response to fertilizer decreased on more fertile soils. Still, fertilizer response varied widely on low fertility soils (e.g. on soils with <10 g kg −1 SOC, responses ranged from −8.6 to 24.4 t ha −1 ), indicating strong interactions between factors governing fertilizer response. Response to fertilizer was reduced if total rainfall <1,500 mm or rainfall from 0 to 3 months after planting <400 mm. Fertilizer application promoted plant growth and resulted in a better soil coverage and reduced weed competition. Yields in fertilized fields were independent of weed management, unless growing conditions were unfavourable.
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Claims 20
Claim · model-written summary
Unfertilized cassava yields ranged from 4.2 to 25.7 t/ha between sites and years
- Taxon
- cassava
Manihot esculentae1 - Outcome
- unfertilized yieldse0
- Value
- 4.2 to 25.7 t ha −1e0
- Qualifier
- between sites and yearse0
- Setting
- Kenya and Ugandae1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average unfertilized yields ranged from 4.2 to 25.7 t ha −1 between sites and years”
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
Claim · model-written summary
Mineral fertilizer significantly increased cassava yields relative to unfertilized plots
- Taxon
- cassavaManihot esculentae1
- Treatment
- Mineral fertilizere2
- Outcome
- yieldse2
- Direction
- increasede2
- Comparator
- unfertilizede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average unfertilized yields ranged from 4.2 to 25.7 t ha −1 between sites and years”
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Mineral fertilizer use increased yields significantly”
Claim · model-written summary
Response to fertilizer in cassava was highly variable, ranging from -0.2 to 15.3 t/ha
- Taxon
- cassavaManihot esculentae1
- Outcome
- response to fertilizere3
- Value
- −0.2 to 15.3 t ha −1e3
- Qualifier
- highly variablee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e3“response to fertilizer was highly variable (−0.2 to 15.3 t ha −1 )”
Claim · model-written summary
Cassava yield response per kg applied N was 37 kg fresh yield in 2004
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied Ne4
- Outcome
- yield response per kg applied nutriente4
- Value
- 37e4
- Qualifier
- in 2004e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Cassava yield response per kg applied N was 106 kg fresh yield in 2005
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied Ne4
- Outcome
- yield response per kg applied nutriente4
- Value
- 106e4
- Qualifier
- in 2004 and 2005e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Cassava yield response per kg applied P was 168 kg fresh yield in 2004
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied N, P and Ke4
- Outcome
- yield response per kg applied nutriente4
- Value
- 168e4
- Qualifier
- in 2004e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Cassava yield response per kg applied P was 482 kg fresh yield in 2005
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied N, P and Ke4
- Outcome
- yield response per kg applied nutriente4
- Value
- 482e4
- Qualifier
- in 2004 and 2005e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Cassava yield response per kg applied K was 45 kg fresh yield in 2004
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied N, P and Ke4
- Outcome
- yield response per kg applied nutriente4
- Value
- 45e4
- Qualifier
- in 2004e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Cassava yield response per kg applied K was 128 kg fresh yield in 2005
- Taxon
- cassavaManihot esculentae1
- Treatment
- applied N, P and Ke4
- Outcome
- yield response per kg applied nutriente4
- Value
- 128e4
- Qualifier
- in 2004 and 2005e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e4“Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005”
Claim · model-written summary
Fertilizer response was governed by soil fertility, rainfall and weed management
- Taxon
- cassavaManihot esculentae1
- Treatment
- soil fertility, rainfall and weed managemente5
- Outcome
- Fertilizer responsee5
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e5“Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age”
Claim · model-written summary
Fertilizer response was not influenced by variety, pest and disease pressure, or harvest age
- Taxon
- cassavaManihot esculentae1
- Treatment
- variety, pest and disease pressure and harvest agee5
- Outcome
- Fertilizer responsee5
- Direction
- not influencede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e5“Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age”
Claim · model-written summary
Relative N and K yields were positively correlated with soil organic carbon and exchangeable K
- Taxon
- cassavaManihot esculentae1
- Treatment
- SOC and exchangeable Ke6
- Outcome
- Relative N and K yieldse6
- Direction
- positively correlatede6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e6“Relative N and K yields were positively correlated to SOC and exchangeable K”
Claim · model-written summary
Response to fertilizer decreased on more fertile soils
- Taxon
- cassavaManihot esculentae1
- Outcome
- response to fertilizere7
- Direction
- decreasede7
- Setting
- more fertile soilse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e7“response to fertilizer decreased on more fertile soils”
Claim · model-written summary
On soils with low SOC (<10 g/kg), cassava fertilizer responses ranged from -8.6 to 24.4 t/ha
- Taxon
- cassavaManihot esculentae1
- Outcome
- responsese2
- Value
- −8.6 to 24.4 t ha −1e2
- Qualifier
- on soils with <10 g kg −1 SOCe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“on soils with <10 g kg −1 SOC, responses ranged from −8.6 to 24.4 t ha −1”
Claim · model-written summary
Response to fertilizer was reduced when total rainfall was below 1,500 mm
- Taxon
- cassavaManihot esculentae1
- Treatment
- total rainfall <1,500 mme2
- Outcome
- Response to fertilizere2
- Direction
- reducede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Response to fertilizer was reduced if total rainfall <1,500 mm or rainfall from 0 to 3 months after planting <400 mm”
Claim · model-written summary
Response to fertilizer was reduced when rainfall from 0 to 3 months after planting was below 400 mm
- Taxon
- cassavaManihot esculentae1
- Treatment
- rainfall from 0 to 3 months after planting <400 mme2
- Outcome
- Response to fertilizere2
- Direction
- reducede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Response to fertilizer was reduced if total rainfall <1,500 mm or rainfall from 0 to 3 months after planting <400 mm”
Claim · model-written summary
Fertilizer application promoted cassava plant growth
- Taxon
- cassavaManihot esculentae1
- Treatment
- Fertilizer applicatione2
- Outcome
- plant growthe2
- Direction
- promotede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Fertilizer application promoted plant growth and resulted in a better soil coverage and reduced weed competition”
Claim · model-written summary
Fertilizer application gave a better soil coverage
- Taxon
- cassavaManihot esculentae1
- Treatment
- Fertilizer applicatione2
- Outcome
- soil coveragee2
- Direction
- bettere2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Fertilizer application promoted plant growth and resulted in a better soil coverage and reduced weed competition”
Claim · model-written summary
Fertilizer application reduced weed competition in cassava
- Taxon
- cassavaManihot esculentae1
- Treatment
- Fertilizer applicatione2
- Outcome
- weed competitione2
- Direction
- reducede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Fertilizer application promoted plant growth and resulted in a better soil coverage and reduced weed competition”
Claim · model-written summary
Yields in fertilized fields were independent of weed management unless growing conditions were unfavourable
- Taxon
- cassavaManihot esculentae1
- Treatment
- weed managemente2
- Outcome
- Yields in fertilized fieldse2
- Direction
- independent ofe2
- Qualifier
- unless growing conditions were unfavourablee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda”
e2“Yields in fertilized fields were independent of weed management, unless growing conditions were unfavourable”
The same questions in other papers
fertilization · yield · Manihot esculenta (cassava)Positive and negative results
140 papers in the same direction as this paper · 10 in the opposite direction · 2 reporting no difference from an alternative
- no effect
- positive
- positive
149 papers more in this group
See all 153 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.