Abstract
This study reports on the land degradation minimizing effects of Conservation Agriculture (CA) as promoted among smallholder Zambian farmers. It found no evidence of CA associated improvements in soil fertility after five years of CA practice, most probably because crop residues were removed from the fields. The study reports high phosphorus (15.53 mg kg-1) and potassium (0.75 cmol kg-1) levels, low nitrogen (0.12 %) and organic carbon (1.19 %) levels, and no plough/hoe pans in soils from both CA and conventionally (CV) managed fields. This is in part contrary to the dominant land degradation narratives which have been the basis for promoting CA in the study areas. Faidherbia albida, a leguminous tree promoted as part of the CA package in Zambia, is associated with significantly higher levels of nitrogen, organic carbon and potassium under its canopy. Its planting by CA farmers is linked to the incentives provided by CA promoters. Average maize yields of 3.8 t ha-1 and 2.8 t ha-1 were reported under CA and CV systems respectively. Government subsidies for mineral fertilizer and hybrid seed promote maize mono-cropping and remain unsupportive of CA. It is concluded that the dominant land degradation narrative, which posits population induced land degradation, may not hold in this case. Instead, the removal of crop residues and low levels of mineral fertilizer and manure amendments may better explain the soil fertility status of the study areas. More nutrient replacement strategies are required if the benefits of CA on soil fertility are to be actualized in the immediate future.
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Claims 10
Claim · model-written summary
After five years, Conservation Agriculture practice gave no evidence of improved soil fertility relative to conventionally managed fields.
- Treatment
- CA practicee1
- Outcome
- soil fertilitye1
- Direction
- no_changeinferrede1
- Comparator
- conventionally (CV) managed fieldse4
Not reportedTaxon
Verbatim
e1“It found no evidence of CA associated improvements in soil fertility after five years of CA practice, most probably because crop residues were removed from the fields”
e4“no plough/hoe pans in soils from both CA and conventionally (CV) managed fields”
Claim · model-written summary
Soil phosphorus is high at 15.53 mg kg-1.
Not reportedTaxon
Verbatim
e2“The study reports high phosphorus (15.53 mg kg-1) and potassium (0.75 cmol kg-1) levels”
Claim · model-written summary
Soil potassium is high at 0.75 cmol kg-1.
Not reportedTaxon
Verbatim
e2“The study reports high phosphorus (15.53 mg kg-1) and potassium (0.75 cmol kg-1) levels”
Claim · model-written summary
Soil nitrogen is low at 0.12 %.
Not reportedTaxon
Verbatim
e3“low nitrogen (0.12 %) and organic carbon (1.19 %) levels”
Claim · model-written summary
Soil organic carbon is low at 1.19 %.
Not reportedTaxon
Verbatim
e3“low nitrogen (0.12 %) and organic carbon (1.19 %) levels”
Claim · model-written summary
No plough or hoe pans occur in soils of either CA or conventionally managed fields.
- Outcome
- plough/hoe panse4
Not reportedTaxonDirection
Verbatim
e4“no plough/hoe pans in soils from both CA and conventionally (CV) managed fields”
Claim · model-written summary
Faidherbia albida canopies have significantly higher nitrogen, organic carbon and potassium levels.
- Taxon
- Faidherbia albida
Faidherbia albidae5 - Outcome
- levels of nitrogen, organic carbon and potassiume5
- Direction
- highere5
- Setting
- under its canopye5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Faidherbia albida, a leguminous tree promoted as part of the CA package in Zambia, is associated with significantly higher levels of nitrogen, organic carbon and potassium under its canopy”
Claim · model-written summary
Average maize yield was about 3.8 t ha-1 under Conservation Agriculture and 2.8 t ha-1 under conventional systems.
- Treatment
- CAe6
- Outcome
- maize yieldse6
- Direction
- higherinferrede6
- Value
- 3.8 t ha-1 and 2.8 t ha-1e6
- Comparator
- CV systemse6
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Average maize yields of 3.8 t ha-1 and 2.8 t ha-1 were reported under CA and CV systems respectively”
Claim · model-written summary
Removal of crop residues and low mineral fertilizer and manure use may better explain soil fertility status than population-induced degradation.
- Outcome
- soil fertility statuse7
- Qualifier
- the removal of crop residues and low levels of mineral fertilizer and manure amendmentse7
Not reportedTaxon
Verbatim
e7“the removal of crop residues and low levels of mineral fertilizer and manure amendments may better explain the soil fertility status of the study areas”
Claim · model-written summary
More nutrient replacement strategies are required for Conservation Agriculture benefits on soil fertility.
- Outcome
- nutrient replacement strategiese1
Not reportedTaxon
Verbatim
e1“More nutrient replacement strategies are required if the benefits of CA on soil fertility are to be actualized in the immediate future”
The same questions in other papers
tillage · yield · Zea mays (maize)Positive and negative results
811 papers in the same direction as this paper · 230 in the opposite direction · 57 reporting no difference from an alternative
- no effect
- negative
- no effect
1,095 papers more in this group
See all 1,099 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.