Abstract
Experiments to assess the yield and economic performance of a maize-groundnut rotation compared with continuous maize (both when inorganic fertilizer was applied to maize and when not), were conducted under management by smallholder farmers in Zimbabwe over six years. The experiment was planted on-station near Harare and at six smallholder sites in northeast Zimbabwe, predominantly on sandy soils. Fertilizer rates and practices were those used by farmers, as described in surveys. On-farm grain yields from continuous maize without fertilizer were generally in the range 0.5–0.8 t ha −1 over five years. Maize yield responses to inorganic fertilizer on smallholder farms were highly variable, but moderate (up to 29 kg grain per kg N) with adequate rainfall. With no inorganic fertilizer applied to maize, the on-station groundnut crop (producing 0.260–0.355 t ha −1 shelled grain) almost doubled the grain yield of the following maize crop (in 1995–96), increasing output from 2.46 t ha −1 to 4.61 t ha −1 . Where inorganic fertilizer was applied to maize, the rotation produced even more additional maize grain (an increase of 2.93 t ha −1 ). Up to 0.50 t ha −1 extra grain was obtained in the second year of maize following groundnut (1996–97). With inorganic fertilizer, groundnut improved the grain yield of following maize crops at only two of five on-farm sites. Without fertilizer, the groundnut rotation increased maize grain yields at five on-farm sites by an average of only 0.28 t ha −1 . For the on-station groundnut and two subsequent years with maize, discounted net benefits (DNBs) over cash costs (seed and fertilizer) were greater for the rotation than for continuous maize, irrespective of whether or not inorganic fertilizer was applied. When labour costs were added, continuous maize plus fertilizer showed better returns than did the rotation, while the returns for the rotation and continuous maize without fertilizer were almost the same. On-farm the rotation was far less profitable. At only two sites, DNBs over cash costs were higher for the rotation whereas DNBs over all costs (including labour valued at a local casual-worker wage) were always negative or close to zero. At three sites, it was far more profitable to grow continuous maize, especially with fertilizer. These findings of low groundnut yield, marginal to zero profitability, and high labour cost of groundnut-maize rotations, support and explain the general trend by smallholder farmers to reduce groundnut area in Zimbabwe.
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Claims 14
Claim · model-written summary
Continuous maize without fertilizer yielded 0.5–0.8 t ha −1 on farms.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On-farm grain yields from continuous maize without fertilizer were generally in the range 0.5–0.8 t ha −1 over five years.”
Claim · model-written summary
Maize yield response to inorganic fertilizer was variable and reached 29 kg grain per kg N with adequate rainfall.
- Treatment
- inorganic fertilizere0
- Outcome
- yield responsese0
- Value
- up to 29 kg grain per kg Ne0
- Qualifier
- adequate rainfalle0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maize yield responses to inorganic fertilizer on smallholder farms were highly variable, but moderate (up to 29 kg grain per kg N) with adequate rainfall.”
Claim · model-written summary
On-station groundnut produced 0.260–0.355 t ha −1 shelled grain.
- Taxon
- groundnut
Arachis hypogaeae0 - Outcome
- shelled graine0
- Value
- 0.260–0.355 t ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“on-station groundnut crop (producing 0.260–0.355 t ha −1 shelled grain)”
Claim · model-written summary
Without inorganic fertilizer, groundnut rotation nearly doubled following maize yield from 2.46 to 4.61 t ha −1.
- Treatment
- groundnut crope0
- Outcome
- grain yield of the following maize crope0
- Direction
- almost doublede0
- Value
- 4.61 t ha −1e0
- Qualifier
- 2.46 t ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With no inorganic fertilizer applied to maize, the on-station groundnut crop (producing 0.260–0.355 t ha −1 shelled grain) almost doubled the grain yield of the following maize crop (in 1995–96), increasing output from 2.46 t ha −1 to 4.61 t ha −1”
Claim · model-written summary
With inorganic fertilizer, rotation added 2.93 t ha −1 of maize grain.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Where inorganic fertilizer was applied to maize, the rotation produced even more additional maize grain (an increase of 2.93 t ha −1 ).”
Claim · model-written summary
A second maize year after groundnut gained up to 0.50 t ha −1 grain.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Up to 0.50 t ha −1 extra grain was obtained in the second year of maize following groundnut (1996–97).”
Claim · model-written summary
With fertilizer, groundnut increased following maize yield at two of five farm sites.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With inorganic fertilizer, groundnut improved the grain yield of following maize crops at only two of five on-farm sites.”
Claim · model-written summary
Without fertilizer, groundnut rotation increased maize yield at five sites by an average 0.28 t ha −1.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Without fertilizer, the groundnut rotation increased maize grain yields at five on-farm sites by an average of only 0.28 t ha −1 .”
Claim · model-written summary
On station, rotation gave greater discounted net benefits over cash costs than continuous maize with or without fertilizer.
- Treatment
- rotatione0
- Outcome
- discounted net benefits (DNBs) over cash costse0
- Direction
- greatere0
- Comparator
- continuous maizee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the on-station groundnut and two subsequent years with maize, discounted net benefits (DNBs) over cash costs (seed and fertilizer) were greater for the rotation than for continuous maize, irrespective of whether or not inorganic fertilizer was applied.”
Claim · model-written summary
Including labour costs, continuous maize plus fertilizer returned more than rotation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When labour costs were added, continuous maize plus fertilizer showed better returns than did the rotation”
Claim · model-written summary
With labour costs, rotation and continuous maize without fertilizer had almost equal returns.
- Treatment
- rotatione0
- Outcome
- returnse0
- Direction
- almost the samee0
- Comparator
- continuous maize without fertilizere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the returns for the rotation and continuous maize without fertilizer were almost the same”
Claim · model-written summary
On farms, rotation gave higher discounted net benefits over cash costs at only two sites.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At only two sites, DNBs over cash costs were higher for the rotation”
t0“PRODUCTIVITY AND PROFITABILITY OF MAIZE”
Claim · model-written summary
On farms, rotation discounted net benefits over all costs were negative or near zero.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DNBs over all costs (including labour valued at a local casual-worker wage) were always negative or close to zero”
t0“PRODUCTIVITY AND PROFITABILITY OF MAIZE”
e1“higher for the rotation whereas DNBs over all costs”
Claim · model-written summary
At three sites, continuous maize was far more profitable, particularly with fertilizer.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At three sites, it was far more profitable to grow continuous maize, especially with fertilizer.”
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