Abstract
SUMMARY Research has proved that integrated soil fertility management (ISFM) can increase crop yields at the field and farm scales. However, its uptake by smallholder farmers in Africa is often constrained by lack of technical guidelines on effective starting points and how the different ISFM options can be combined to increase crop productivity on a sustainable basis. A 4-year study was conducted on sandy soils (<10% clay) on smallholder farms in eastern Zimbabwe to assess how sequencing of different ISFM options may lead to incremental gains in soil productivity, enhanced efficiency of resource use, and increase crop yields at field scale. The sequences were primarily based on low-quality organic resources, nitrogen-fixing green manure and grain legumes, and mineral fertilizers. To enable comparison of legume and maize grain yields among treatments, yields were converted to energy (kilocalories) and protein (kg) equivalents. In the first year, ‘Manure-start’, a cattle manure-based sequence, yielded 3.4 t ha −1 of maize grain compared with 2.5 and 0.4 t ha −1 under a woodland litter-based sequence (‘Litter-start’) and continuous unfertilized maize control, respectively. The ‘Manure-start’ produced 12 × 10 6 kilocalories (kcal); significantly ( p < 0.05) out-yielding ‘Litter start’ and a fertilizer-based sequence (‘Fertilizer-start’) by 50%. A soyabean-based sequence, ‘Soya-start’, gave the highest protein production of 720 kg against <450 kg for the other sequencing treatments. In the second year, the sequences yielded an average of 5.7 t ha −1 of maize grain, producing over 19 × 10 6 kcal and 400 kg of protein. Consequently, the sequences significantly out-performed farmers’ designated poor fields by ~ fivefold. In the third year, ‘Soya-start’ gave the highest maize grain yield of 3.7 t ha −1 ; translating to 1.5 and 3 times more calories than under farmers’ designated rich and poor fields, respectively. In the fourth year, ‘Fertilizer-start’ produced the highest calories and protein of 14 × 10 6 kcal and 340 kg, respectively. Cumulatively over 4 years, ‘Manure-start’ and ‘Soya-start’ gave the highest calories and protein, out-performing farmers’ designated rich and poor fields. Sunnhemp ( Crotalaria juncea L.)-based sequences, ‘Green-start’ and ‘Fertilizer-start’, recorded the highest gains in plant available soil P of ~ 4 mg kg −1 over the 4-year period. Assessment of P agronomic efficiencies showed significantly more benefits under the ISFM-based sequences than under farmers’ designated rich and poor fields. Based on costs of seed, nutrients and labour, ‘Soya-start’ gave the best net present value over the 4 years, while ‘Fertilizer-start’ was financially the least attractive. Overall, the ISFM-based sequences were more profitable than fields designated as rich and poor by farmers. We concluded that ISFM-based sequences can provide options for farm-level intensification by different categories of smallholder farmers in Southern Africa.
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Claims 20
Claim · model-written summary
First-year Manure-start produced 3.4 t ha −1 of maize grain.
- Treatment
- Manure-starte0
- Outcome
- maize graine0
- Direction
- yieldede0
- Value
- 3.4 t ha −1e0
- Comparator
- continuous unfertilized maize controle0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the first year, ‘Manure-start’, a cattle manure-based sequence, yielded 3.4 t ha −1 of maize grain compared with 2.5 and 0.4 t ha −1 under a woodland litter-based sequence (‘Litter-start’) and continuous unfertilized maize control, respectively”
Claim · model-written summary
First-year Litter-start produced 2.5 t ha −1 of maize grain.
- Treatment
- Litter-starte0
- Outcome
- maize graine0
- Direction
- yieldede0
- Value
- 2.5e0
- Comparator
- continuous unfertilized maize controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the first year, ‘Manure-start’, a cattle manure-based sequence, yielded 3.4 t ha −1 of maize grain compared with 2.5 and 0.4 t ha −1 under a woodland litter-based sequence (‘Litter-start’) and continuous unfertilized maize control, respectively”
Claim · model-written summary
First-year Manure-start produced 12 × 10 6 kcal, 50% more than Litter-start and Fertilizer-start.
- Treatment
- Manure-starte0
- Outcome
- kilocalories (kcal)e0
- Direction
- out-yieldinge0
- Value
- 12 × 10 6 kilocalories (kcal)e0
- Qualifier
- 50%e0
- Comparator
- Litter starte0
Not reportedTaxon
Verbatim
e0“The ‘Manure-start’ produced 12 × 10 6 kilocalories (kcal); significantly ( p < 0.05) out-yielding ‘Litter start’ and a fertilizer-based sequence (‘Fertilizer-start’) by 50%”
Claim · model-written summary
Soya-start had the highest protein production at 720 kg, versus under 450 kg for other sequences.
Verbatim
e0“A soyabean-based sequence, ‘Soya-start’, gave the highest protein production of 720 kg against <450 kg for the other sequencing treatments”
Claim · model-written summary
Second-year sequences averaged 5.7 t ha −1 maize grain.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the second year, the sequences yielded an average of 5.7 t ha −1 of maize grain”
Claim · model-written summary
Second-year sequences produced over 19 × 10 6 kcal.
Not reportedTaxon
Verbatim
e0“producing over 19 × 10 6 kcal and 400 kg of protein”
Claim · model-written summary
Second-year sequences produced 400 kg protein.
Not reportedTaxon
Verbatim
e0“producing over 19 × 10 6 kcal and 400 kg of protein”
Claim · model-written summary
Second-year sequences significantly outperformed poor fields by about fivefold.
- Treatment
- sequencese0
- Outcome
- out-performede0
- Direction
- out-performede0
- Value
- ~ fivefolde0
- Comparator
- farmers’ designated poor fieldse0
Not reportedTaxon
Verbatim
e0“the sequences significantly out-performed farmers’ designated poor fields by ~ fivefold”
Claim · model-written summary
Third-year Soya-start gave the highest maize yield at 3.7 t ha −1.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the third year, ‘Soya-start’ gave the highest maize grain yield of 3.7 t ha −1”
Claim · model-written summary
Third-year Soya-start produced 1.5 times more calories than rich fields.
Not reportedTaxon
Verbatim
e0“translating to 1.5 and 3 times more calories than under farmers’ designated rich and poor fields, respectively”
e1“In the third year, ‘Soya-start’ gave the highest maize grain yield”
Claim · model-written summary
Third-year Soya-start produced three times more calories than poor fields.
Not reportedTaxon
Verbatim
e0“translating to 1.5 and 3 times more calories than under farmers’ designated rich and poor fields, respectively”
e1“In the third year, ‘Soya-start’ gave the highest maize grain yield”
Claim · model-written summary
Fourth-year Fertilizer-start produced the highest calories at 14 × 10 6 kcal.
Not reportedTaxonComparator
Verbatim
e0“In the fourth year, ‘Fertilizer-start’ produced the highest calories and protein of 14 × 10 6 kcal and 340 kg, respectively”
Claim · model-written summary
Fourth-year Fertilizer-start produced the highest protein at 340 kg.
Not reportedTaxonComparator
Verbatim
e0“In the fourth year, ‘Fertilizer-start’ produced the highest calories and protein of 14 × 10 6 kcal and 340 kg, respectively”
Claim · model-written summary
Across four years, Manure-start and Soya-start had the highest calories and protein, exceeding rich and poor fields.
- Treatment
- Manure-start’ and ‘Soya-starte0
- Outcome
- calories and proteine0
- Direction
- higheste0
- Comparator
- farmers’ designated rich and poor fieldse0
Not reportedTaxon
Verbatim
e0“Cumulatively over 4 years, ‘Manure-start’ and ‘Soya-start’ gave the highest calories and protein, out-performing farmers’ designated rich and poor fields”
Claim · model-written summary
Green-start and Fertilizer-start increased plant-available soil phosphorus by about 4 mg kg −1 over four years.
- Taxon
- Crotalaria juncea L.
Crotalaria junceae0 - Treatment
- Green-start’ and ‘Fertilizer-starte0
- Outcome
- plant available soil Pe0
- Direction
- highest gainse0
- Value
- ~ 4 mg kg −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunnhemp ( Crotalaria juncea L.)-based sequences, ‘Green-start’ and ‘Fertilizer-start’, recorded the highest gains in plant available soil P of ~ 4 mg kg −1 over the 4-year period”
Claim · model-written summary
Fertility sequences had significantly greater P agronomic efficiency than rich and poor fields.
- Treatment
- ISFM-based sequencese0
- Outcome
- P agronomic efficienciese0
- Direction
- more benefitse0
- Comparator
- farmers’ designated rich and poor fieldse0
Not reportedTaxon
Verbatim
e0“Assessment of P agronomic efficiencies showed significantly more benefits under the ISFM-based sequences than under farmers’ designated rich and poor fields”
Claim · model-written summary
Soya-start had the best four-year net present value.
Not reportedTaxon
Verbatim
e0“‘Soya-start’ gave the best net present value over the 4 years”
Claim · model-written summary
Fertilizer-start was the least financially attractive sequence.
Not reportedTaxon
Verbatim
e0“‘Fertilizer-start’ was financially the least attractive”
Claim · model-written summary
ISFM sequences were more profitable than farmer-designated rich and poor fields.
- Treatment
- ISFM-based sequencese0
- Outcome
- profitablee0
- Direction
- more profitablee0
- Comparator
- fields designated as rich and poor by farmerse0
Not reportedTaxon
Verbatim
e0“the ISFM-based sequences were more profitable than fields designated as rich and poor by farmers”
Claim · model-written summary
The authors conclude ISFM sequences offer farm-level intensification options for Southern African smallholders.
- Outcome
- options for farm-level intensificatione0
Not reportedTaxon
Verbatim
e0“ISFM-based sequences can provide options for farm-level intensification by different categories of smallholder farmers in Southern Africa”
The same questions in other papers
fertilization · organism · Zea mays (maize)Results differ
136 papers in the same direction as this paper · 20 in the opposite direction · 5 reporting no difference from an alternative
- negative
- no effect
- no effect
158 papers more in this group
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