Sustainable intensification through rotations with grain legumes in Sub-Saharan Africa: A review

Franke, A.C.; Brand, G.J. van den; Vanlauwe, Bernard; Giller, Ken E.

doi:10.1016/j.agee.2017.09.029

Cited by 180 publications

(205 citation statements)

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“…Inclusion of leguminous crops in cropping systems can reduce the mineral fertilizer N requirement for the subsequent crop (Jensen et al, 2012). A meta-analysis for SSA revealed that this residual effect of legumes can result in 450-700 kg/ha extra maize yield (Franke, Van Den Brand, Vanlauwe, & Giller, 2017). This potentially lowers the input of mineral fertilizer by 0-51 kg N/ha resulting in 0.03-12.18 Mton CO 2 eqv.…”

Section: Methodological Considerations and Uncertaintiesmentioning

confidence: 99%

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Loon¹,

Hijbeek²,

Berge³

et al. 2019

Global Change Biology

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Cropping is responsible for substantial emissions of greenhouse gasses (GHGs) worldwide through the use of fertilizers and through expansion of agricultural land and associated carbon losses. Especially in sub‐Saharan Africa (SSA), GHG emissions from these processes might increase steeply in coming decades, due to tripling demand for food until 2050 to match the steep population growth. This study assesses the impact of achieving cereal self‐sufficiency by the year 2050 for 10 SSA countries on GHG emissions related to different scenarios of increasing cereal production, ranging from intensifying production to agricultural area expansion. We also assessed different nutrient management variants in the intensification. Our analysis revealed that irrespective of intensification or extensification, GHG emissions of the 10 countries jointly are at least 50% higher in 2050 than in 2015. Intensification will come, depending on the nutrient use efficiency achieved, with large increases in nutrient inputs and associated GHG emissions. However, matching food demand through conversion of forest and grasslands to cereal area likely results in much higher GHG emissions. Moreover, many countries lack enough suitable land for cereal expansion to match food demand. In addition, we analysed the uncertainty in our GHG estimates and found that it is caused primarily by uncertainty in the IPCC Tier 1 coefficient for direct N2O emissions, and by the agronomic nitrogen use efficiency (N‐AE). In conclusion, intensification scenarios are clearly superior to expansion scenarios in terms of climate change mitigation, but only if current N‐AE is increased to levels commonly achieved in, for example, the United States, and which have been demonstrated to be feasible in some locations in SSA. As such, intensifying cereal production with good agronomy and nutrient management is essential to moderate inevitable increases in GHG emissions. Sustainably increasing crop production in SSA is therefore a daunting challenge in the coming decades.

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Section: Methodological Considerations and Uncertaintiesmentioning

confidence: 99%

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Loon¹,

Hijbeek²,

Berge³

et al. 2019

Global Change Biology

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“…Increased productivity of maize after a grain legume relative to maize after maize has been widely reported in the Guinea savanna of West Africa (Sauerborn et al, 2000;Sanginga et al, 2002;Franke et al, 2018). The N contributed to the soil by grain legumes and non-N benefits of rotating grain legumes with maize (pests and diseases suppression, improved soil properties, soil microbial biomass and activity) have been reported to account for the increased productivity of maize after grain legumes (Stevenson and van Kessel, 1996;Giller, 2001;Yusuf et al, 2009b).…”

Section: Cropping System Diversification With Grain Legumesmentioning

confidence: 97%

“…This suggests that the increased maize grain yield after soybean in the HF field in the NGS was largely due to non-N benefits (e.g. increased soil microbial biomass and functioning, improved soil structure, improved N mineralisation) (Giller, 2001, Sanginga et al, 2002Yusuf et al, 2009b;Franke et al, 2018). Residual effects of fixed N2 on maize performance are likely to be more important in LF fields than in HF fields, but the results from the current trial do not provide clear evidence for this.…”

Section: N2-fixation and Net N Contribution To The Soil For A Subsequmentioning

confidence: 99%

“…Legume-cereal rotations are well known for increasing yields of cereals that succeed the legumes even without applying N fertiliser to maize. A systematic review of literature on this system by Franke et al (2018) revealed a mean of 0.49 t ha -1 increase in yield of cereals rotated with legumes relative to continuous cropping of cereals in sub-Saharan Africa. In the Guinea savanna of West Africa, research attention has focused largely on this system owing to the opportunity of increasing yields of the main food security crops without additional N fertiliser cost to farmers (e.g.…”

Section: Legume-cereal Rotation: Sustainable Intensification Pathway mentioning

confidence: 99%

“…The increased yields of maize following legumes are partly due to N contributed by the legumes through biological N2 fixation to improve soil fertility (Giller, 2001;Yusuf et al, 2009a). Non-N benefits, such as reduced pests and diseases incidence, increased soil microbial biomass and activity, and improved soil properties may also contribute to the increased yield of maize in rotation with legumes (Giller, 2001;Yusuf et al, 2009b;Franke et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Sustainable intensification and diversification options with grain legumes for smallholder farming systems in the Guinea savanna of Ghana

Kermah

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at 4 p.m. in the Aula. iv Michael Kermah (2020) Sustainable intensification and diversification options with grain legumes for smallholder farming systems in the Guinea savanna of Ghana. 157 pages. PhD Thesis, Wageningen University, Wageningen, NL (2020). With references and summary in English ISBN: 978-94-6395-228-6 DOI: https://doi.org/10.18174/507853v To my late beloved big sister, Janet Ebah Kermah, your toil to ensure the family succeeds will never be in vain, you will forever live in my heart, our hearts. vi vii AbstractFood security is a critical issue in the Guinea savanna of Ghana where about 60% of the rural population, mostly smallholder farmers are food insecure. Food insecurity results from poor crop yields due to low soil fertility compounded by erratic unimodal rainfall and the inability of households to purchase required supplemental food. Rapid population growth means that the numbers of food insecure people are likely to increase, necessitating sustainable intensification and diversification to increase crop production per unit area of land. This thesis focused on testing spatial and temporal intensification and diversification options suitable for the variable biophysical and socio-economic conditions of smallholder farming systems in the Guinea savanna to increase productivity, mitigate the risk of crop failure, and thus to increase food selfsufficiency. One site in the southern Guinea savanna and one in the northern Guinea savanna were selected which differed in biophysical and socio-economic resources. In each site, field experiments were conducted on three fields differing in soil fertility (fertile, medium fertile, poorly fertile) to quantify: N2-fixation and N contribution to soil fertility by grain legumes in sole and intercropping; impact of replacement intercropping on increasing resource use efficiency and crop productivity; and productivity of relay (additive) intercropping and rotation of grain legumes with maize. Scenario analysis was performed with data from the N2AfricaGhana project supplemented with data from the on-farm experiments and literature to test the impacts of intensification and diversification options on household food self-sufficiency. Sole legumes fixed larger amounts of N2 than under intercropping. The soil N balance was generally positive and similar between intercrops and sole crops suggesting that both systems could be sustainable intensification and diversification options. Poor fields stimulated grain legumes to rely on atmospheric N2 for growth leading to more positive soil N balances than in fertile fields. Consequently, legumes in poor fields were more competitive with maize and led to greater intercrop yield advantage than in fertile fields. Across all fields and sites, intercropping enhanced the efficiency in resource use resulting in a 26% to 46% yield advantage over sole cropping. Intercrops were more efficient and productive in the drier northern Guinea savanna than in the wetter southern Guinea savanna. Yet the absolute larger grain yields achieved i...

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Evaluating pearl millet and mungbean intercropping in the semi‐arid regions of Senegal

et al. 2020

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Pearl millet [Pennisetum glaucum (L.) R. Br.] yields in Senegal are constrained by rainfall variability, persistent drought, and low soil fertility. Mungbean [Vigna radiata (L.) Wilczek], a short-duration and relatively drought-tolerant legume crop, is capable of improving soil fertility and productivity of associated crops. Our study evaluated the effects of pearl millet and mungbean intercropping on crop yields in the semi-arid regions of Senegal. Field experiments were conducted during the 2017 and 2018 growing seasons at Bambey and Nioro sites located within Senegal's west-central and Saloum agricultural regions, respectively. Experimental treatments: monocropped millet (T 1), monocropped mungbean (T 2 , 100%), and 23% (T 3), 43% (T 4), 47% (T 5), 62% (T 6), 125% (T 7), and 164% (T 8) of mungbean intercropped with millet were laid out in a randomized complete block design and replicated four times. In addition to yield, canopy cover and normalized difference vegetation index (NDVI) were measured and yield advantage was assessed with the land equivalent ratio (LER). Combined millet and mungbean seed yields were up to 60 and 85% higher under intercropping systems compared to millet monocropping at Bambey and Nioro, respectively. Similarly, LER was always greater than unity (> 1) under millet-mungbean intercropping compared to millet monocropping. Mean canopy cover estimates and NDVI values increased by up to 60 and 30% in millet-mungbean intercropping over millet grown alone, respectively. These combined yield gains obtained without fertilizer applications suggested that optimizing mungbean density (62-125%) in pearl millet-based systems can increase the combined yields in a low-input and/or high-risk environment in Senegal.

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Sustainable intensification through rotations with grain legumes in Sub-Saharan Africa: A review

Cited by 180 publications

References 136 publications

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Sustainable intensification and diversification options with grain legumes for smallholder farming systems in the Guinea savanna of Ghana

Evaluating pearl millet and mungbean intercropping in the semi‐arid regions of Senegal

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