Abstract
Cassava-maize intercropping is a common practice among smallholder farmers in Southern Nigeria. It provides food security and early access to income from the maize component. However, yields of both crops are commonly low in farmers’ fields. Multi-locational trials were conducted in Southern Nigeria in 2016 and 2017 to investigate options to increase productivity and profitability through increased cassava and maize plant densities and fertilizer application. Trials with 4 and 6 treatments in 2016 and 2017, respectively were established on 126 farmers’ fields over two seasons with a set of different designs, including combinations of two levels of crop density and three levels of fertilizer rates. The maize crop was tested at low density (LM) with 20,000 plants ha−1 versus high density (HM) with 40,000 plants ha−1. For cassava, low density (LC) had had 10,000 plants ha−1 versus the high density (HC) with 12,500 plants ha−1.; The fertilizer application followed a regime favouring either the maize crop (FM: 90 kg N, 20 kg P and 37 kg K ha−1) or the cassava crop (FC: 75 kg N, 20 kg P and 90 kg K ha−1), next to control without fertilizer application (F0). Higher maize density (HM) increased marketable maize cob yield by 14 % (3700 cobs ha−1) in the first cycle and by 8% (2100 cobs ha−1) in the second cycle, relative to the LM treatment. Across both cropping cycles, fertilizer application increased cob yield by 15 % (5000 cobs ha−1) and 19 % (6700 cobs ha−1) in the FC and FM regime, respectively. Cassava storage root yield increased by 16 % (4 Mg ha−1) due to increased cassava plant density, and by 14 % (4 Mg ha−1) due to fertilizer application (i.e., with both fertilizer regimes) but only in the first cropping cycle. In the second cycle, increased maize plant density (HM) reduced cassava storage root yield by 7% (1.5 Mg ha−1) relative to the LM treatment. However, the negative effect of high maize density on storage root yield was counteracted by fertilizer application. Fresh storage root yield increased by 8% (2 Mg ha−1) in both fertilizer regimes compared to the control without fertilizer application. Responses to fertilizer by cassava and maize varied between fields. Positive responses tended to decline with increasing yields in the control treatment. The average value-to-cost ratio (VCR) of fertilizer use for the FM regime was 3.6 and higher than for the FC regime (VCR = 1.6), resulting from higher maize yields when FM than when FC was applied. Revenue generated by maize constituted 84–91% of the total revenue of the cropping system. The highest profits were achieved with the FM regime when both cassava and maize were grown at high density. However, fertilizer application was not always advisable as 34 % of farmers did not realize a profit. For higher yields and profitability, fertilizer recommendations should be targeted to responsive fields based on soil fertility knowledge.
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Claims 17
Claim · model-written summary
Higher maize density raised marketable cob yield 14% in the first cycle.
- Treatment
- Higher maize density (HM)e0
- Outcome
- marketable maize cob yielde0
- Direction
- increasede0
- Value
- 14 %e0
- Qualifier
- in the first cyclee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher maize density (HM) increased marketable maize cob yield by 14 % (3700 cobs ha−1) in the first cycle”
Claim · model-written summary
Higher maize density raised marketable cob yield 8% in the second cycle.
- Treatment
- Higher maize density (HM)e0
- Outcome
- marketable maize cob yielde0
- Direction
- increasede0
- Value
- 8%e0
- Qualifier
- in the second cyclee0
- Comparator
- LM treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher maize density (HM) increased marketable maize cob yield by 14 % (3700 cobs ha−1) in the first cycle and by 8% (2100 cobs ha−1) in the second cycle, relative to the LM treatment”
Claim · model-written summary
The cassava-favoring fertilizer regime raised cob yield 15% across cycles.
Not reportedTaxonComparator
Verbatim
e0“Across both cropping cycles, fertilizer application increased cob yield by 15 % (5000 cobs ha−1) and 19 % (6700 cobs ha−1) in the FC and FM regime, respectively”
Claim · model-written summary
The maize-favoring fertilizer regime raised cob yield 19% across cycles.
Not reportedTaxonComparator
Verbatim
e0“Across both cropping cycles, fertilizer application increased cob yield by 15 % (5000 cobs ha−1) and 19 % (6700 cobs ha−1) in the FC and FM regime, respectively”
Claim · model-written summary
Higher cassava density raised storage-root yield 16%.
- Taxon
- Cassava
Manihot esculentae0 - Treatment
- increased cassava plant densitye0
- Outcome
- storage root yielde0
- Direction
- increasede0
- Value
- 16 %e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cassava storage root yield increased by 16 % (4 Mg ha−1) due to increased cassava plant density”
Claim · model-written summary
Fertilizer raised cassava storage-root yield 14% only in the first cycle.
- Taxon
- CassavaManihot esculentae0
- Treatment
- fertilizer applicatione0
- Outcome
- storage root yielde0
- Direction
- increasede0
- Value
- 14 %e0
- Qualifier
- only in the first cropping cyclee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cassava storage root yield increased by 16 % (4 Mg ha−1) due to increased cassava plant density, and by 14 % (4 Mg ha−1) due to fertilizer application (i.e., with both fertilizer regimes) but only in the first cropping cycle”
Claim · model-written summary
Higher maize density reduced cassava root yield 7% in the second cycle.
- Taxon
- cassavaManihot esculentae0
- Treatment
- increased maize plant density (HM)e0
- Outcome
- storage root yielde0
- Direction
- reducede0
- Value
- 7%e0
- Comparator
- LM treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the second cycle, increased maize plant density (HM) reduced cassava storage root yield by 7% (1.5 Mg ha−1) relative to the LM treatment”
Claim · model-written summary
Fertilizer counteracted the adverse effect of high maize density on cassava root yield.
- Treatment
- fertilizer applicatione0
- Outcome
- storage root yielde0
- Direction
- counteractede0
- Comparator
- high maize densitye0
Not reportedTaxon
Verbatim
e0“the negative effect of high maize density on storage root yield was counteracted by fertilizer application”
Claim · model-written summary
Fertilizer raised fresh storage-root yield 8% versus no fertilizer.
- Treatment
- both fertilizer regimese0
- Outcome
- Fresh storage root yielde0
- Direction
- increasede0
- Value
- 8%e0
- Comparator
- control without fertilizer applicatione0
Not reportedTaxon
Verbatim
e0“Fresh storage root yield increased by 8% (2 Mg ha−1) in both fertilizer regimes compared to the control without fertilizer application”
Claim · model-written summary
Cassava and maize fertilizer responses varied between fields.
- Taxon
- cassava and maizeManihot esculenta
Zea mayse0 - Outcome
- Responses to fertilizere0
- Direction
- variede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Responses to fertilizer by cassava and maize varied between fields”
Claim · model-written summary
Positive fertilizer responses tended to decline as control yields rose.
Not reportedTaxon
Verbatim
e0“Positive responses tended to decline with increasing yields in the control treatment”
Claim · model-written summary
The maize-favoring fertilizer regime had an average value-to-cost ratio of 3.6.
Not reportedTaxon
Verbatim
e0“The average value-to-cost ratio (VCR) of fertilizer use for the FM regime was 3.6”
Claim · model-written summary
The maize-favoring fertilizer regime had a higher value-to-cost ratio than the cassava-favoring regime.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher than for the FC regime (VCR = 1.6), resulting from higher maize yields when FM than when FC was applied”
Claim · model-written summary
Maize accounted for 84–91% of total system revenue.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Revenue generated by maize constituted 84–91% of the total revenue of the cropping system”
Claim · model-written summary
The highest profits occurred with the maize-favoring fertilizer regime and high density of both crops.
- Taxon
- cassava and maizeManihot esculentaZea mayse0
- Treatment
- FM regimee0
- Outcome
- profitse0
- Direction
- higheste0
- Qualifier
- both cassava and maize were grown at high densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest profits were achieved with the FM regime when both cassava and maize were grown at high density”
Claim · model-written summary
Thirty-four percent of farmers did not profit from fertilizer application.
Not reportedTaxon
Verbatim
e0“fertilizer application was not always advisable as 34 % of farmers did not realize a profit”
Claim · model-written summary
The authors recommend targeting fertilizer to responsive fields using soil fertility knowledge.
Verbatim
e0“fertilizer recommendations should be targeted to responsive fields based on soil fertility knowledge”
t0“cassava-maize”
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