Abstract
Core Ideas Mean maize response to N is similar in Kenya, Tanzania, and Rwanda. Maize is relatively more responsive to nitrogen in Malawi and Rwanda. Maize is responsive to phosphorus and potassium in Rwanda. There is little potential for profitable response to phosphorus and potassium in most areas of East Africa. Maize response to Mg–S–Zn–B needs more investigation in Rwanda. Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa. Research was conducted to determine macronutrient response functions and to diagnose Mg–S–Zn–B deficiencies. Site–year × N‐rate interactions within countries often accounted for little variation in yield relative to the N‐rate effect. Country mean grain yield responses to N‐rate were curvilinear to plateau, but linear in Malawi. Although mean yields differed, the response to N was similar for Kenya, Tanzania, and Zambia with a mean yield increase of 0.94 Mg ha −1 due to 50 kg ha −1 N compared with 1.59 Mg ha −1 for Malawi and Rwanda. Response to N was related to yield with no fertilizer applied ( r = 0.40). Only Rwanda had mean responses to P and K with respective yield increases of 0.99 and 0.22 Mg ha −1 due to 15 kg ha −1 . Application of Mg–S–Zn–B caused a mean yield increase of 0.73 Mg ha −1 in Rwanda but had no effect in other countries. Application of affordable fertilizer to twice as much land at 50% compared with 100% of the economically optimum rate results in mean gains of 50% for production and agronomic efficiency and 72% for profit/cost ratio. Soil test results were not related to response to applied nutrients but historical yield appears to be weakly predictive of N response. The determined country‐level P and K response functions can be widely applied, except for Kenya, in consideration of other available information. The response to Mg–S–Zn–B in Rwanda needs further investigation.
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Claims 15
Claim · model-written summary
Country mean grain yield responded to N rate in a curvilinear-to-plateau pattern, but linearly in Malawi.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e1“Country mean grain yield responses to N‐rate were curvilinear to plateau, but linear in Malawi”
Claim · model-written summary
Mean yield increase due to 50 kg N ha −1 was 0.94 Mg ha −1 in Kenya, Tanzania and Zambia.
- Treatment
- 50 kg ha −1 Ne2
- Outcome
- mean yielde2
- Direction
- increasee2
- Value
- 0.94 Mg ha −1e2
- Comparator
- Malawi and Rwandae2
- Setting
- Kenya, Tanzania, and Zambiae2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e2“Although mean yields differed, the response to N was similar for Kenya, Tanzania, and Zambia with a mean yield increase of 0.94 Mg ha −1 due to 50 kg ha −1 N compared with 1.59 Mg ha −1 for Malawi and Rwanda”
Claim · model-written summary
Mean yield increase due to 50 kg N ha −1 was 1.59 Mg ha −1 in Malawi and Rwanda.
- Treatment
- 50 kg ha −1 Ne2
- Outcome
- mean yielde2
- Direction
- increasee2
- Value
- 1.59 Mg ha −1e2
- Comparator
- Kenya, Tanzania, and Zambiae2
- Setting
- Malawi and Rwandae2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e2“Although mean yields differed, the response to N was similar for Kenya, Tanzania, and Zambia with a mean yield increase of 0.94 Mg ha −1 due to 50 kg ha −1 N compared with 1.59 Mg ha −1 for Malawi and Rwanda”
Claim · model-written summary
Response to N was related to yield where no fertilizer was applied (r = 0.40).
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e4“Response to N was related to yield with no fertilizer applied ( r = 0.40)”
Claim · model-written summary
In Rwanda, P application increased maize yield by 0.99 Mg ha −1 at 15 kg ha −1.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e5“Only Rwanda had mean responses to P and K with respective yield increases of 0.99 and 0.22 Mg ha −1 due to 15 kg ha −1”
Claim · model-written summary
In Rwanda, K application increased maize yield by 0.22 Mg ha −1 at 15 kg ha −1.
- Treatment
- Ke5
- Outcome
- yielde5
- Direction
- increasese5
- Value
- 0.22 Mg ha −1e5
- Qualifier
- 15 kg ha −1e5
- Setting
- Rwandae5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e5“Only Rwanda had mean responses to P and K with respective yield increases of 0.99 and 0.22 Mg ha −1 due to 15 kg ha −1”
Claim · model-written summary
Application of Mg–S–Zn–B increased maize yield by 0.73 Mg ha −1 in Rwanda.
- Treatment
- Application of Mg–S–Zn–Be6
- Outcome
- mean yielde6
- Direction
- increasee6
- Value
- 0.73 Mg ha −1e6
- Setting
- Rwandae6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e6“Application of Mg–S–Zn–B caused a mean yield increase of 0.73 Mg ha −1 in Rwanda but had no effect in other countries”
Claim · model-written summary
Application of Mg–S–Zn–B had no effect on maize yield in other countries.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e6“Application of Mg–S–Zn–B caused a mean yield increase of 0.73 Mg ha −1 in Rwanda but had no effect in other countries”
Claim · model-written summary
Affordable fertilizer at 50% of the economically optimum rate on twice the land gave a mean gain of 50% in production and agronomic efficiency.
- Treatment
- Application of affordable fertilizer to twice as much land at 50%e7
- Outcome
- production and agronomic efficiencye7
- Direction
- gainse7
- Value
- 50%e7
- Comparator
- 100% of the economically optimum ratee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e7“Application of affordable fertilizer to twice as much land at 50% compared with 100% of the economically optimum rate results in mean gains of 50% for production and agronomic efficiency and 72% for profit/cost ratio”
Claim · model-written summary
Affordable fertilizer at 50% of the economically optimum rate on twice the land gave a mean gain of 72% in profit/cost ratio.
- Treatment
- Application of affordable fertilizer to twice as much land at 50%e7
- Outcome
- profit/cost ratioe7
- Direction
- gainse7
- Value
- 72%e7
- Comparator
- 100% of the economically optimum ratee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e7“Application of affordable fertilizer to twice as much land at 50% compared with 100% of the economically optimum rate results in mean gains of 50% for production and agronomic efficiency and 72% for profit/cost ratio”
Claim · model-written summary
Soil test results were not related to maize response to applied nutrients.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e1“Soil test results were not related to response to applied nutrients”
Claim · model-written summary
Historical yield appears to be weakly predictive of maize N response.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e2“historical yield appears to be weakly predictive of N response”
Claim · model-written summary
The authors recommend that the country-level P and K response functions be widely applied, except for Kenya.
- Outcome
- P and K response functionse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e3“The determined country‐level P and K response functions can be widely applied, except for Kenya”
Claim · model-written summary
There is little potential for profitable response to phosphorus and potassium in most areas of East Africa.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e4“There is little potential for profitable response to phosphorus and potassium in most areas of East Africa”
Claim · model-written summary
Site-year by N-rate interactions within countries often accounted for little variation in maize yield.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Information is scarce for maize ( Zea mays L.) response to nutrient application for many production areas in tropical Africa”
e5“Site–year × N‐rate interactions within countries often accounted for little variation in yield relative to the N‐rate effect”
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