Abstract
The Collaborative Study of Cassava in Africa (COSCA) undertook cassava yield and soil fertility surveys in sub-Saharan Africa in 1991 with the objectives of obtaining average yields from farmers' fields and determining factors which could account for the yield differences across the various climate, altitude, population density and market access zones - the site selection factors considered in the study. In this analysis, the contributions of various soil properties determined from the fields were also obtained and evaluated. The cassava yield parameters considered were fresh root and shoot weight, harvest index and cassava stand density. The interaction between the site selection factors had a greater significant effect on the yield parameters than the individual factors. Whereas the effect of climate was not significant (P = 0.1), both climate x market access and population x market access interactions were highly significant (P 0.01) on root yield. The overall mean root yield was estimated as 13.1 t/ha. It was highest in the subhumid followed by nonhumid and lowland humid zones, and least in the highland humid zone. It was significantly (P 0.05) higher (13.6 t/ha) in the low altitude zones than in the mid (8.5 t/ha) altitude zones. The results of stepwise regression analysis showed that the total contribution of soil variables to root yield variations ranged from about 30% for the entire sub-region through 32% in the lowland and about 40% in nonhumid zones to more than 45% in the highland humid zones. The contribution of total sulphur to the total variations in root yield was consistently high in both the sub-region and across the climate zones compared to other soil variables evaluated. The overall contributions of the soil variables to shoot yield, harvest index and stand density were approximately 35%, 30% and 50%, respectively. Though the contributions of the soil properties to cassava performance confirmed that other factors are also important in cassava production, the significant roles of individual soil variables both in the sub-region and across the climate zones have been established. Keywords: cassava, soil properties, regression, subSaharan Africa> Agro-Science Vol. 6 (1) 2007: pp. 1-16
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 15
Claim · model-written summary
Interactions among site factors affected cassava yield parameters more than individual factors.
- Taxon
- cassava
Manihot esculentat0 - Outcome
- yield parameterse0
- Direction
- greatere0
- Comparator
- individual factorse0
- Setting
- site selection factorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The interaction between the site selection factors had a greater significant effect on the yield parameters than the individual factors.”
t0“cassava”
Claim · model-written summary
Climate alone had no significant effect on yield parameters.
- Taxon
- cassavaManihot esculentat0
- Outcome
- effect of climatee0
- Setting
- climatee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of climate was not significant (P = 0.1)”
t0“cassava”
Claim · model-written summary
Climate by market access interaction significantly affected root yield.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yielde0
- Setting
- climate x market accesse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both climate x market access and population x market access interactions were highly significant (P 0.01) on root yield.”
t0“cassava”
Claim · model-written summary
Population by market access interaction significantly affected root yield.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yielde0
- Setting
- population x market accesse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both climate x market access and population x market access interactions were highly significant (P 0.01) on root yield.”
t0“cassava”
Claim · model-written summary
Mean cassava root yield was 13.1 t/ha.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yielde0
- Value
- 13.1 t/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall mean root yield was estimated as 13.1 t/ha.”
t0“cassava”
Claim · model-written summary
Root yield was highest in subhumid zones and lowest in highland humid zones.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yielde1
- Direction
- higheste0
- Comparator
- highland humid zonee0
- Setting
- subhumide0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It was highest in the subhumid followed by nonhumid and lowland humid zones, and least in the highland humid zone.”
t0“cassava”
e1“The overall mean root yield”
Claim · model-written summary
Low altitude zones had greater root yield than mid altitude zones.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yielde1
- Direction
- highere0
- Value
- 13.6 t/hae0
- Comparator
- mid (8.5 t/ha) altitude zonese0
- Setting
- low altitude zonese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It was significantly (P 0.05) higher (13.6 t/ha) in the low altitude zones than in the mid (8.5 t/ha) altitude zones.”
t0“cassava”
e1“The overall mean root yield”
Claim · model-written summary
Soil variables explained about 30% of root yield variation across the subregion.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yield variationse0
- Value
- about 30%e0
- Comparator
- soil variablese0
- Setting
- entire sub-regione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total contribution of soil variables to root yield variations ranged from about 30% for the entire sub-region through 32% in the lowland and about 40% in nonhumid zones to more than 45% in the highland humid zones.”
t0“cassava”
Claim · model-written summary
Soil variables explained 32% of lowland root yield variation.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yield variationse0
- Value
- 32%e0
- Comparator
- soil variablese0
- Setting
- lowlande0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total contribution of soil variables to root yield variations ranged from about 30% for the entire sub-region through 32% in the lowland and about 40% in nonhumid zones to more than 45% in the highland humid zones.”
t0“cassava”
Claim · model-written summary
Soil variables explained about 40% of nonhumid root yield variation.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yield variationse0
- Value
- about 40%e0
- Comparator
- soil variablese0
- Setting
- nonhumid zonese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total contribution of soil variables to root yield variations ranged from about 30% for the entire sub-region through 32% in the lowland and about 40% in nonhumid zones to more than 45% in the highland humid zones.”
t0“cassava”
Claim · model-written summary
Soil variables explained more than 45% of highland humid root yield variation.
- Taxon
- cassavaManihot esculentat0
- Outcome
- root yield variationse0
- Value
- more than 45%e0
- Comparator
- soil variablese0
- Setting
- highland humid zonese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total contribution of soil variables to root yield variations ranged from about 30% for the entire sub-region through 32% in the lowland and about 40% in nonhumid zones to more than 45% in the highland humid zones.”
t0“cassava”
Claim · model-written summary
Total sulphur contributed consistently more to root yield variation than other soil variables.
- Taxon
- cassavaManihot esculentat0
- Compound
- total sulphure0
- Outcome
- variations in root yielde0
- Direction
- highe0
- Comparator
- other soil variables evaluatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The contribution of total sulphur to the total variations in root yield was consistently high in both the sub-region and across the climate zones compared to other soil variables evaluated.”
t0“cassava”
Claim · model-written summary
Soil variables contributed about 35% to shoot yield.
- Taxon
- cassavaManihot esculentat0
- Outcome
- shoot yielde0
- Value
- 35%e0
- Comparator
- soil variablese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall contributions of the soil variables to shoot yield, harvest index and stand density were approximately 35%, 30% and 50%, respectively.”
t0“cassava”
Claim · model-written summary
Soil variables contributed about 30% to harvest index.
- Taxon
- cassavaManihot esculentat0
- Outcome
- harvest indexe0
- Value
- 30%e0
- Comparator
- soil variablese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall contributions of the soil variables to shoot yield, harvest index and stand density were approximately 35%, 30% and 50%, respectively.”
t0“cassava”
Claim · model-written summary
Soil variables contributed about 50% to stand density.
- Taxon
- cassavaManihot esculentat0
- Outcome
- stand densitye0
- Value
- 50%e0
- Comparator
- soil variablese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall contributions of the soil variables to shoot yield, harvest index and stand density were approximately 35%, 30% and 50%, respectively.”
t0“cassava”