Separating the Agronomic Effects of Burning and Biomass Removal in a Typical Slash and Burn Rotation System in Southern Cameroon

Biological Agriculture & Horticulture

Bengono

Bitomo

2008

Self Cite

Maize was relay cropped with the cover crops Mucuna pruriens or Pueraria phaseoloides for between one and seven consecutive years in three sites: Ngoungoumou, located in an area of low land use intensity (LUI), about 100 krn away from the next major market, and at Evendissi and Andok, in a medium LUI area, 15 to 20 krn away from the next major market. Maize performance was compared with that in a natural fallow system, with fallow biomass burned versus retained as mulch in both fallow types. Fallow type had no effect on maize density. After biomass burning higher maize densities were attained at the low LUI site. Maize cob production was affected neither by fallow type nor by biomass management. Across seven years of cropping, marketable cob production in the low LUI site was 38.5% higher in mucuna fallow than in natural fallow (p < 0.06). Differences at p < 0.05 were found in one out of seven years. In the medium LUI sites, mucuna and pueraria fallow increased marketable cob production by 70--132% (p < 0.001).Maize grain yield was closely related to the marketable cob production in all sites. In the low LUI site the cumulative maize grain yield over seven years was 30% higher in mucuna fallow than in natural fallow (p < 0.07), the difference being significant at p < 0.05 in only one year.In the medium LUI sites maize grain yield was 65% higher in mucuna fallow (p < 0.001) and 69-94% higher in pueraria fallow (p < 0.001). Burning biomass had a cumulative grain yield advantage of 33% at the low LUI site (p < 0.053), with significant (p < 0.02) differences in two out of seven years. Biomass burning had no effects on maize grain yield in the medium LUI sites. No interactions between fallow type and biomass management were found. Despite the lack of frequent significant advantages of the cover crop fallows in the low LUI site, the system can be recommended because it has the potential to increase food diversity and security; in the medium LUI sites farmers were immediately convinced of the benefits of the system and have since moved on to grow high value vegetable crops.

Section: Discussioncontrasting

confidence: 60%

Short- and Long-term Maize Yield Response toMucuna pruriensandPueraria phaseoloidesRelay Fallow and Biomass Burning Versus Mulching in the Forest Zone of Southern Cameroon

Biological Agriculture & Horticulture

Bengono

Bitomo

2008

Self Cite

“…On the other hand, the export of the wood would result in a less intensive burn with potentially less negative effects on the soil. Norgrove et al (2003) have shown at the same site that burning of short fallow biomass has a negative impact on crop growth. No information on the consequences of nutrient removal with wood in short fallow systems could be found.…”

Section: Discussionmentioning

confidence: 95%

Biomass production, nutrient uptake and partitioning in plantedSenna spectabilis,Flemingia macrophyllaandDactyladenia barterifallow systems over three fallow/cropping cycles on Ultisol

Archives of Agronomy and Soil Science

2008

Biomass production and nutrient uptake of all components in planted Senna spectabilis, Dactyladenia barteri and Flemingia macrophylla hedgerow fallow were determined after three two-year fallow phases and compared to natural fallow. Total above-ground biomass production after each of three fallow phases was significantly higher in the Senna system than any other system. Total above ground biomass production in the Flemingia and the Dactyladeniai system was not different from that in natural fallow. The volunteer biomass between hedgerows was only once significantly reduced by S. spectabilis during the first fallow phase. The amount of litter did not differ between fallow systems. The biomass of S. spectabilis, F. macrophylla and D. barteri comprised 96%, 95% and 65% wood, respectively. Relative to the total system biomass, wood constituted 67% in S. spectabilis and about 20% in F. macrophylla and D. barteri systems. Except for Mg, the S. spectabilis system accumulated more nutrients in above ground biomass than any other system. The highest nutrient uptake achieved in the S. spectabilis system was 335 kg ha 71 N, 331 kg ha 71 Ca, 230 kg ha 71 K, and 39 kg ha 71 P. Relative to the S. spectabilis system, nutrient accumulation, except for Mg, was the lowest in the natural fallow control followed by the F. macrophylla and the D. barteri system. In F. macrophylla and S. spectabilis, 95% and 85% of the nutrients were accumulated in the wood. In D. barteri the nutrient distribution between leaves and wood was approximately equal. Export of wood would remove 9-16% of the nutrients accumulated in the F. macrophylla and D. barteri systems but 27-53% in the S. spectabilis system. Potential consequences of different biomass management options for crop yields and fallow re-growth are discussed.

“…Maize dry grain yields were estimated through plot harvests, grain separation, and dry matter determination (Norgrove et al 2003a; Hauser et al 2008). Plants were counted, cobs were removed, counted, husked, and weighed fresh.…”

Section: Methodsmentioning

confidence: 99%

“…Due to theft and a requirement to abandon the latter field, a field of plantain after 20 years of fallow was additionally included (Hauser and Mekoa 2009 ; Hauser et al 2012a ). Additionally, we selected plots with reduced fallow scenarios whereby maize was cropped after 2 years of fallow (Norgrove et al 2003a , 2003b ); and plantain after 6 years of fallow (Norgrove et al 2003a , 2003b ). Site locations were Andok, Ekombitié, Ngoumbou, Bilik, and Zoatoupsie, respectively (Fig.…”

Section: Methodsmentioning

confidence: 99%

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Estimating the Consequences of Fire Exclusion for Food Crop Production, Soil Fertility, and Fallow Recovery in Shifting Cultivation Landscapes in the Humid Tropics

Norgrove

Environmental Management

2014

In the Congo Basin, smallholder farmers practice slash-and-burn shifting cultivation. Yet, deliberate burning might no longer be sustainable under reduced fallow scenarios. We synthesized data from the Forest Margins Benchmark Area (FMBA), comprising 1.54 million hectares (ha), in southern Cameroon and assessed the impact of fire exclusion on yield, labor inputs, soil fertility, ecosystem carbon stocks, and fallow recovery indicators in two common field types (plantain and maize) under both current and reduced fallow scenarios. While we could not distinguish between impacts of standard farmer burning practice and fire exclusion treatments for the current fallow scenario, we concluded that fire exclusion would lead to higher yields, higher ecosystem carbon stocks as well as potentially faster fallow recovery under the reduced fallow scenario. While its implementation would increase labor requirements, we estimated increased revenues of 421 and 388 US$ ha−1 for plantain and maize, respectively. Applied to the FMBA, and assuming a 6-year reduced fallow scenario, fire exclusion in plantain fields would potentially retain 240,464 Mg more ecosystem carbon, comprising topsoil carbon plus tree biomass carbon, than standard farmer practice. Results demonstrate a potential “win–win scenario” where yield benefits, albeit modest, and conservation benefits can be obtained simultaneously. This could be considered as a transitional phase towards higher input use and thus higher yielding systems.