Crop Production In sub-Saharan Africa Research Articles

Integrated Soil Fertility and Water Management Practices for Enhanced Agricultural Productivity

Declining agricultural productivity has been a challenge worldwide and especially in Sub-Saharan Africa (SSA). Low agricultural productivity has been attributed to factors such as poor farm management practices, soil moisture stress, soil infertility, and soil degradation, among others. The nations in the SSA are prone to insufficient crop yields due to their inadequate capacity to adapt to good agricultural practices that support crop productivity such as integrated soil fertility and water management (ISFWM) practices. This lowers the farmers’ capacity to improve crop productivity, thus contributing in jeopardizing the food and nutritional security in SSA. Past research has shown that ISFWM strategies have not been properly adopted probably due to the lack of adequate awareness among the farmers about them. In addition, there is limited documentation on the importance of ISFWM in enhancement of soil fertility, water use efficiency, and sustainable crop production in SSA. This paper discusses some of the key ISFWM options that have the potential to enhance soil fertility, improve water use efficiency, and consequently increase agricultural productivity. The practices include intercropping, use of tied ridges, minimum tillage, mulching, and combined use of organic and inorganic fertilizers.

Genetic resources and breeding of maize for Striga resistance: a review.

The potential yield of maize (Zea mays L.) and other major crops is curtailed by several biotic, abiotic, and socio-economic constraints. Parasitic weeds, Striga spp., are major constraints to cereal and legume crop production in sub-Saharan Africa (SSA). Yield losses reaching 100% are reported in maize under severe Striga infestation. Breeding for Striga resistance has been shown to be the most economical, feasible, and sustainable approach for resource-poor farmers and for being environmentally friendly. Knowledge of the genetic and genomic resources and components of Striga resistance is vital to guide genetic analysis and precision breeding of maize varieties with desirable product profiles under Striga infestation. This review aims to present the genetic and genomic resources, research progress, and opportunities in the genetic analysis of Striga resistance and yield components in maize for breeding. The paper outlines the vital genetic resources of maize for Striga resistance, including landraces, wild relatives, mutants, and synthetic varieties, followed by breeding technologies and genomic resources. Integrating conventional breeding, mutation breeding, and genomic-assisted breeding [i.e., marker-assisted selection, quantitative trait loci (QTL) analysis, next-generation sequencing, and genome editing] will enhance genetic gains in Striga resistance breeding programs. This review may guide new variety designs for Striga-resistance and desirable product profiles in maize.

A meta‐analysis of the effects of Striga control methods on maize, sorghum, and major millets production in sub‐Saharan Africa

AbstractParasitic Striga weeds severely damage cereal crops in sub‐Saharan Africa (SSA), leading to yield losses in susceptible varieties. A range of Striga control methods are commonly recommended, including cultural practices, chemical herbicides, biological control agents, and host resistance, either as solo treatments or in combinations of these approaches (i.e., integrated Striga management [ISM]). A limited number of studies compared the relative efficacy of the recommended Striga control methods, or their combinations for ISM, in cereal crop production in SSA. The objective of this paper was to undertake a meta‐analysis and provide a detailed comparison of the Striga control methods in the production of maize, sorghum, and the major millets, as a guide to effective Striga management. The study was conducted as a meta‐analysis of 66 research articles that reported on various control measures. The following agronomic data were collected: grain yield (GY) response of the assessed crops and Striga parameters such as damage rating score (SDR) and emergence count (SEC). Maize varieties possessing Striga‐resistant genes displayed high mean yield values at 2053.00 kg ha−1, varying from 281.00 to 6260.00 kg ha−1, and a mean SDR of 4.70, ranging from 2.00 to 7.00. Likewise, sorghum varieties with Striga resistance genes achieved greater GY with a mean yield response of 1738.00 kg ha−1, ranging from 850.00 to 2162.00 kg ha−1. A relatively low GY was achieved in maize and sorghum production when deploying ISM (e.g., cultural control + host resistance and host resistance + chemical herbicides) and chemical Striga control. Effective ISM and pre‐ and post‐emergent herbicides have not yet been identified for Striga control and yield gains. Striga damage negatively affected GY in maize, as revealed by the significant correlation (r = −0.36, P < 0.001) between GY and SDR. A relatively weak correlation was detected in maize between GY and SEC (r = 0.003, P = 0.96). Sorghum GY was negatively correlated with SEC, although nonsignificantly (r = −0.30, P = 0.36). Few studies have evaluated Striga control methods in pearl millet and finger millet, limiting the opportunity for an effective comparison. The study recommends SDR as the best selection criterion for improving GY performance in maize, while SEC and SDR are the parameters of choice in sorghum selection programs for better GY under Striga infestation. Overall, the meta‐analysis indicates that host resistance is the most effective method for controlling Striga infestation and boosting GY in maize and sorghum. There is an ongoing need for research into the best combinations of the reported control methods as a sound basis for the recommendation of an ISM package across target production environments of common cereals in Africa.

Biological control interventions reduce pest abundance and crop damage while maintaining natural enemies in sub-Saharan Africa: a meta-analysis.

Insect pests are a major challenge to smallholder crop production in sub-Saharan Africa (SSA), where access to synthetic pesticides, which are linked to environmental and health risks, is often limited. Biological control interventions could offer a sustainable solution, yet an understanding of their effectiveness is lacking. We used a meta-analysis approach to investigate the effectiveness of commonly used biocontrol interventions and botanical pesticides on pest abundance (PA), crop damage (CD), crop yield (Y) and natural enemy abundance (NEA) when compared with controls with no biocontrol and with synthetic pesticides. We also evaluated whether the magnitude of biocontrol effectiveness was affected by type of biocontrol intervention, crop type, pest taxon, farm type and landscape configuration. Overall, from 99 studies on 31 crops, we found that compared to no biocontrol, biocontrol interventions reduced PA by 63%, CD by over 50% and increased Y by over 60%. Compared to synthetic pesticides, biocontrol resulted in comparable PA and Y, while NEA was 43% greater. Our results also highlighted that the potential for biocontrol to be modulated by landscape configuration is a critical knowledge gap in SSA. We show that biocontrol represents an effective tool for smallholder farmers, which can maintain yields without associated negative pesticide effects. Furthermore, the evidence presented here advocates strongly for including biocontrol practices in national and regional agricultural policies.

Amendment with Burkina Faso phosphate rock-enriched composts alters soil chemical properties and microbial structure, and enhances sorghum agronomic performance

Low soil available phosphorus (P) severely limits crop production in sub-Saharan Africa. The present study evaluated phosphate rock-enriched composts as locally available low-cost fertilizers for sorghum production. The treatments consisted of sorghum straw, compost (COMP), phosphate rock (BPR), BPR-enriched compost (P-COMP), BPR-rhizosphere soil-enriched compost (P-COMP-SOIL), nitrogen-phosphorus-potassium treatment (NPK, 60–39–25), and control (NK, 60–25). Sorghum straw and compost were applied at 1.34 tons ha−1. N, P, and K in all treatments, excluding the control, were adjusted to 60, 39, and 25 kg ha−1, with urea, BPR, and KCl, respectively. Sorghum vr. kapelga was cultivated and soil samples were collected at the S5, S8, and S9 growth stages. P-COMP-SOIL and NPK yielded better sorghum yields than the other treatments. The rhizosphere soil of P-COMP-SOIL had high abundance of soil bacteria and AMF, and genes involved in P solubilization, such as: acid phosphatase (aphA), phosphonatase (phnX), glucose dehydrogenase (gcd), pyrroloquinoline quinone (pqqE), phosphate-specific transporter (pstS). The superior performance of the P-COMP-SOIL was associated with its higher available P content and microbial abundance. Multivariate analysis also revealed vital contributions of N, carbon, and exchangeable cations to sorghum growth. Soils could be amended with phosphate rock-rhizosphere soil-enriched composts, as an alternative to chemical fertilizers.

Improving Physic Nut (Jatropha curcas) – a Bio-fuel and Multipurpose Crop Production in Sub-Saharan Africa through Appropriate Nursery Media

Physic nut (Jatropha curcas) is a bio-fuel and multipurpose crop that can be used to produce biodiesel, biogas and latex. The toxic substances – curcin and diterpenoids in raw Jatropha leaves and seeds can scare grazing animals away and this suggests the possibility of using the plant as live fence to curb cattle menace which is one of the major constraints facing crop production in Sub-Saharan Africa especially in Nigeria. Despite its nutritive, medicinal and economic values, Jatropha is one of the most neglected crops in Nigeria and in sub-Sahara Africa at large. There is often loss of vigour of Jatropha seedlings due to high seed oil content which results in rancidity and weak seedling growth. An experiment was conducted at Enugu State Polytechnic, Iwollo, Enugu state, Nigeria to determine the appropriate nursery media towards improving the production of Jatropha curcas in sub-Saharan Africa. Four nursery media viz: 3:2:1; 1:2:1; 0:0:1 and; 1:0:0 of top soil, organic manure and river sand respectively, were evaluated. The experiment was laid out in Completely Randomized Design (CRD) with three replications. Data on emergence percentage, seedling height, number of leaves per seedling and seedling girth were collected and analyzed using Analysis of variance (ANOVA) for CRD. The treatment means with significant differences were separated using least significant difference at 0.05 probability level. The results showed that there was no significant difference (p>0.05) among the treatments in emergence percentage of Jatropha curcas. However, there were significant differences (p<0.05) among the treatments in seedling height and stem girth with the highest values obtained in 1:2:1 of top soil, poultry droppings and river sand, respectively and the least in 0:0:1 of top soil, poultry droppings and river sand, respectively. It could be concluded that the use of 1:2:1 of top soil, organic manure and river sand, respectively significantly improved seedling growth of Jatropha curcas compared to the other treatments and could therefore be recommended for Jatropha curcas nursery for improved production of the crop in sub-Sahara Africa.

Plant parasitic nematodes and disease severity of common bean lines evaluated for reaction to root knot nematodes infestation

Plant parasitic nematodes are important pests in crop production in sub-Saharan Africa. The objective of this study was to identify the occurrence of nematodes associated with common bean (Phaseolus vulgaris L.) and evaluate breeding lines for their reaction to Meloidogyne spp. in Ghana. Common bean rhizosphere soil was sampled and processed using Modified Baermann Tray method. Five nematode genera, namely Meloidogyne, Pratylenchus, Rotylenchulus, Helicotylenchus and Trichodorus were extracted. The first four genera listed above were prevalent across locations, with Trichodorus present in 30% of the fields sampled. The highest nematode population density of 319 juveniles per 200 cubic centimeter of soil was recorded for Meloidogyne spp. compared to 45 juveniles per 200 cubic centimeter, for Trichodorus. Twelve breeding lines were evaluated by inoculating roots of two-weeks-old plants with 2000 infective-stage juveniles of Meloidogyne sp. Reactions of test lines to Meldogyne sp. infection were assessed by determining the number of egg masses and galling index (GI) on roots. Reproduction index (RI) was used to classify test lines as resistant or susceptible. Significant differences (P < 0.05) were observed in the number of eggs, GI and RI among lines tested. No resistant line was identified; however, lines SEF 47, BFS 35 and BFS 60 were moderately resistant, with RI of 13.1, 17.4 and 23.7%, respectively. Line SEF 60, although classified as slightly resistant, recorded a 100 seed weight of 26.0 g, which was 60% higher than line SEF 53 with seed weight of 16.2 g. Moderately resistant common bean lines identified could be used in common bean improvement programmes to develop elite cultivars tolerant to root knot nematodes.

Can Tanzania\u2019s adaptation measures prevent future maize yield decline? A simulation study from Singida region

Cereal crop production in sub-Saharan Africa has not achieved the much-needed increase in yields to foster economic development and food security. Maize yields in the region’s semi-arid agroecosystems are constrained by highly variable rainfall, which may be worsened by climate change. Thus, the Tanzanian government has prioritized agriculture as an adaptation sector in its intended nationally determined contribution, and crop management adjustments as a key investment area in its Agricultural Sector Development Programme. In this study, we investigated how future changes in maize yields under different climate scenarios can be countered by regional adjusted crop management and cultivar adaptation strategies. A crop model was used to simulate maize yields in the Singida region of Tanzania for the baseline period 1980–2012 and under three future climate projections for 2020–2060 and 2061–2099. Adaptation strategies to improve yields were full irrigation, deficit irrigation, mulch and nitrogen addition and another cultivar. According to our model results, increase in temperature is the main driver of future maize yield decline. Increased respiration and phenological development were associated with lower maize yields of 16% in 2020–2060 and 20% in 2061–2099 compared to the 1980–2012 baseline. Surprisingly, none of the management strategies significantly improved yields; however, a different maize variety that was tested as an alternative coping strategy performed better. This study suggests that investment in accessibility of improved varieties and investigation of maize traits that have the potential to perform well in a warmer future are better suited for sustaining maize production in the semi-arid region than adjustments in crop management.

Site-specific responses of lowland rice to acidulated and calcined phosphate rock fertilizers in the Center-West region of Burkina Faso.

Soil phosphorus (P) deficiency is a major constraint of crop production in Sub-Saharan Africa. In particular, in the Sudano-Sahelian zone of Burkina Faso, P is rarely replenished as fertilizer supplies are limited in rural areas and because of the socio-economic situation of farmers. There is however, an abundance of local phosphate rock resource in the country. The development of local inorganic P fertilizers to improve crop production and replace the nutrients removed after harvesting, as well as to promote to sustainable agriculture, is desired. This study evaluated the efficiency of low-grade Burkina Faso phosphate rock (BPR)-based P fertilizers, produced by acidulation and calcination-the major fertilizer processing methods, on lowland rice production and the soil factors influencing their effectiveness. The results showed that the acidulated P fertilizers were as effective as conventional commercial P fertilizers on various soil types, textures, and fertility. Calcined P fertilizers were consistently effective on fine-textured soils with high basic fertility. It was found that fine soil texture and basic fertility of the initial soils were important factors in agronomic efficiency of BPR-based fertilizers and the resilience of rice production to climatic variability. It is recommended that soil type, with respect to soil texture, soil properties, inherent fertility, and water availability, should be considered when using BPR-based fertilizers for rice cultivation.

Population and breeding patterns of the pest rodent: Mastomys natalensis in a maize dominated agroecosystem in Lake Victoria crescent zone, Eastern Uganda

Multimammate mice (Mastomys natalensis) are a key rodent pest species to cereal crop production in Sub-Saharan Africa. This study aimed at generating information on the population fluctuation and breeding patterns of M. natalensis in a maize dominated agro-ecosystem in the Mayuge district, Eastern Uganda. The area is characterised by a bimodal rainfall pattern with rains in the periods March to May and August to November. A Capture–Mark–Recapture study was established in cultivated and fallow field habitats with, in each habitat, two plots of 60 m by 60 m with 49 evenly spaced trapping points. Trapping was conducted monthly for three consecutive nights, and the study extended from January 2016 to June 2018. A Generalised Linear Mixed Model analysis showed significantly higher population density estimates (β = 0.69, p < 0.0001) in fallow land compared to cultivated fields, and also significantly higher density estimates( β = 0.75, p = 0.006) in the first wet season and lowest in the first dry season. The percentage breeding females differed significantly across months (χ 2 = 27.05, df = 11, p = 0.003) and seasons (χ 2 = 17.64, p = 0.0003). Breeding females occurred throughout all the months of trapping, but with significantly higher percentages in the months of March to July (i.e. first wet season extending to second dry season) and generally lowest in the first dry months (i.e. January and February in 2017, and February 2018). The results of this study have important consequences for the timing of control efforts, and recommends that control should be initiated during the dry seasons prior to wet seasons to counteract potential damaging population build up in later wet seasons when crop planting is expected.

Maize production under combined Conservation Agriculture and Integrated Soil Fertility Management in the sub-humid and semi-arid regions of Kenya

Abstract Crop production in Sub-Saharan Africa (SSA) is constrained by rainfall variability and declining soil fertility. This has over time led to a decrease in crop yield, among them also maize. This decrease is also experienced in the sub-humid and semi-arid locations of Kenya. Among the commonly used soil and water management practices in SSA are Conservation Agriculture (CA) and integrated soil fertility management (ISFM). Crop response to these management practices is influenced by the existence of soil fertility gradients which are common among smallholder farmers. This paper presents results from a study done in the sub-humid and semi-arid location of Kenya, focusing on the effects of CA- and/or ISFM-based practices on maize yield. Trials were set out on farms within the two locations using a one farm one replicate randomized design. In each farm, CA-based treatment, no tillage with residue retention (NTR), ISFM-based treatment, conventional tillage with use of manure (CTM), a combination of CA + ISFM, no tillage with residue retention and use of manure (NTRM) and a control, (C) were laid down on fields representing high and low fertility soils. The trials started in the long rains of 2017 (LR2017) running for four seasons i.e., LR2017, short rains 2017 (SR2017), long rains 2018 (LR2018) and short rains 2018 (SR2018). Soil water content (SWC) and nitrogen use efficiency (NUE) were also monitored and evaluated. In either high or low fertility fields, maize grain yield was significantly different between the control and both NTR, CTM and NTRM with no significant differences between NTR, CTM and NTRM. Maize grain yield increase compared to the control was highest under ISFM in the low fertility fields in both locations and all seasons. For example, during the last season, SR2018, NTR, CTM and NTRM significantly increased maize grain yield by 136 %, 297 %, and 208 %, respectively, compared to the control, in the low fertility fields of sub-humid Kibugu. In the semi-arid Machang’a, the increase by NTR, CTM and NTRM, respectively, in the low fertility fields was 146 %, 379 % and 183 % for SR2018. This was linked to the tendency of ISFM to improve crop yield in the short run. For both locations, SWC and NUE were highest under NTR. In the sub-humid Kibugu, during SR2018, at the grain filling stage, 78 days after sowing, SWC under NTR, CTM and NTRM was higher by 16 %, 9 % and 20 %, respectively, compared to the control. Also at 78 days after sowing, in the semi-arid Machang’a, SWC was 18 %, 7 % and 15 % significantly higher under NTR, CTM and NTRM, respectively, compared to the control. The higher SWC observed under NTR and NTRM was related to no tillage with residue retention while under CTM it was related to improved soil organic matter through manure addition. NUE, on the other hand, was 26 % and 23 % in Kibugu and Machang’a, respectively, and lowest under the combined practice (NTRM), i.e., 19 % and 15 % in Kibugu and Machang’a, respectively. The high NUE under CA was attributed to the placement of urea in the planting holes while maintaining residue on the soil surface. The low NUE under NTRM was linked to fertilizer N immobilization. Lastly, from the biomass yield, our study showed that monocrop maize under NTR requires a kick-starting by an ISFM-based practice in the low fertility fields of the semi-arid region.

Birds and bats contribute to natural regulation of the millet head miner in tree-crop agroforestry systems

A better understanding of environmental factors driving natural pest regulation is a major challenge for designing sustainable cropping systems. The objective of the present study was to assess the association between vegetation openness in traditional tree-crop agroforestry systems in Senegal, richness and abundance of vertebrates including insectivorous birds and bats, and their contribution to the natural regulation of crop pests. The millet head miner (MHM), Heliocheilus albipunctella (Lepidoptera, Noctuidae), a major constraint to increasing millet crop productivity in sub-Saharan Africa, was selected as a model system. Ten sites separated by at least one km from each other were selected in a 100 km2 study area in the Peanut basin in Senegal. In each site, a pair of millet fields distant from at least 100 m each was selected according to a gradient of vegetation openness within a 100-m radius buffer with sampling plot (5 × 5 m) at the center. Nine insectivorous bird and bat species were recorded in millet fields over the 2017 cropping season and their predator status was confirmed by direct observation or DNA detection in fecal samples. Grain losses were reduced when panicles were accessible to birds and bats, confirming their net contribution to pest regulation. At a local scale, tree diversity and vegetation openness were important predictors of the abundance of insectivorous village weaver birds and grey-headed sparrows, respectively. Some tree species (soapberry trees and neems) indirectly contributed to natural regulation of the MHM likely by providing refuges to insectivorous vertebrates whereas other tree species (baobabs) provided disservices as possible refuges for the MHM moths. Further research is needed to better understand relationships between tree cover, food web interactions and natural pest suppression, so that specific conservation measures such as habitat management can be designed to improve pest control.

Striga resistance and compatibility of maize genotypes to a biocontrol agent, Fusarium oxysporum f.sp.strigea

ABSTRACTStriga presents a major threat to cereal crop production in sub-Saharan Africa. A combined use of host resistance and biological control agents holds promise as a key strategy for sustainable, integrated Striga management in maize (Zea mays L.) production. The objective of this study was to determine resistance against Striga asiatica (L.) Kuntze and compatibility of selected maize genotypes to a biocontrol agent, Fusarium oxysporum f.sp. strigae (FOS), for integrated Striga management. Eighteen maize genotypes were evaluated under glasshouse and field conditions using three treatments: 1) maize genotypes sown without Striga infestation and FOS treatment (control), 2) maize genotypes grown under Striga infestation and; 3) FOS-treated maize genotypes grown under Striga infestation. The results showed that genotype-by-FOS interaction significantly (P < 0.05) affected all traits, except anthesis-to-silking interval, ear aspect score and Striga emergence count at 8 weeks after planting. All maize and Striga traits were significantly affected by FOS treatment (P < 0.001), although the efficacy of FOS seemed to be maize genotype dependent. Mean grain yield was 4.2 t ha−1 for the control, 2.63 t ha−1 for the FOS-treated and 2.17 t ha−1 for the untreated genotypes. Overall, the combined effect of host resistance and inoculation of seed with FOS reduced parasitic infestations and Striga damage symptoms, resulting in improved agronomic performance. Five genotypes (ZM1523, ZM 1423, ZM 1421, NC QPM and Colorado) showed resistance to S. asiatica and compatibility to FOS. The study demonstrated the efficacy of host resistance and biological control in integrated management of S. asiatica in maize.

Long-term effects of integrated soil fertility management practices on soil chemical properties in the Sahel

Joint application of mineral and organic fertilizers and incorporation of legumes into cropping systems, known as integrated soil fertility management (ISFM), has improved short-term crop productivity in sub-Saharan Africa. Little research exists, however, on the effectiveness of long-term ISFM in improving soil quality and productivity. This study determined the long-term effects of different ISFM treatments on soil chemical properties and OM dynamics up to 20 cm soil depth at a long-term research site at Saria, Burkina Faso. The ISFM treatments applied from 1960 to 2008 included broadcasted fertilizer (100 kg ha−1 14-23-14 (NPK) with 50 kg ha−1 urea; and NPK with an additional 50 kg ha−1 urea and 50 kg ha−1 KCl) supplemented with crop residue retention, and with manure application at 5000 or 40000 kg ha−1. In addition, continuous cropping of Sorghum bicolor (sorghum) was compared to yearly rotation between sorghum and Vigna unguiculata (cowpea). The large manure rate (40,000 kg ha−1) supplement was most effective in buffering fertilizer-application-induced pH decline and increasing grain yield, soil carbon (C), nitrogen (N), and phosphorus (P) concentrations (p < 0.05). Manure application also enhanced the microbial cycling and retention of C and N microbial byproducts compared to other fertilizer treatments, as indicated by C and N X-ray Absorption Near Edge Structure (XANES) spectroscopies. Legume-cereal cropping led to increased abundance of C and N functional groups indicative of reduced OM breakdown compared to the continuous cropping system. Supplemental application of manure with mineral fertilizers under mixed cereal-legume cropping was found to be most effective in improving long-term soil fertility and crop productivity in the Sahel.

Roles of eco-friendly low input technologies in crop production in sub-Saharan Africa

The global population doubled in the past decades and the situation is more serious in sub-Saharan African Countries. This also resulted in increased demand for biofuels, land, water, and increased...

Food security impacts of industrial crop production in sub-Saharan Africa: a systematic review of the impact mechanisms

A number of industrial crops have been promoted in sub-Saharan Africa (SSA) to meet a range of policy objectives including economic growth, rural development, agricultural modernization and energy security. The food security impacts of industrial crop production have received extensive policyattention and have been widely discussed in the academic literature. There is, however, an overall lack of a clear understanding of these impacts due to thelarge diversity of industrial crops, and their varied modes of production, expansion areas, and impact mechanisms. This systematic review synthesizes theavailable knowledge on the interface of industrial crops and food security in SSA. In particular we identify key patterns with how different industrial cropsand impact mechanisms are represented and studied in the current literature, and how they intersect to affect food security. The current literature isfragmented, as most studies focus on single or small subsets of crops and impact mechanisms. Most studies capture mechanisms related to food access andavailability, rather than to food utilization and stability. A clustering analysis identified the main literature clusters that combine mechanisms related to foodavailability, access to food, and environmental impact. The overall analysis presented in this systematic review allowed us to identify priority policy andpractice domains that need to be targeted in order to improve the food security outcomes of industrial crop production in SSA.

Fertiliser adoption and sustainable rural livelihood improvement in Nigeria

Poor soil fertility emanating from land degradation is one of the causes of low crop productivity in Sub-Saharan Africa. Therefore, the issues of food insecurity and poverty have become prevalent in these countries. It is however imperative to explore agricultural innovations such as mineral fertiliser to improve soil fertility of the arable lands in Africa including Nigeria. In this study, we analyse the adoption of mineral fertiliser and its economic impacts on the livelihoods of 400 rural farmers in Nigeria. We apply the endogenous switching regression and propensity score matching approaches in the empirical analyses. We find that the adoption of mineral fertiliser increases cassava yields and net revenues of rural farmers. The enhanced cassava yields and net revenues have implications on the transformation of rural economy by reducing food insecurity, minimising poverty, and improving the overall well-being of rural farmers. The results also show that farmer age and leasing negatively influence the adoption of fertiliser whereas farmer education, experience in cassava farming, household size, keeping of farm record, location differential, access to credit, membership of farmer association, and herbicides show positive effects. To achieve higher adoption of fertiliser among rural farmers, we recommend that agricultural policies could target the aforementioned key factors.

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

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 N2 O 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.

Long-term application of low C:N residues enhances maize yield and soil nutrient pools across Kenya

Declines in soil fertility and limited access to inorganic nitrogen (N) fertilizer constrain crop production in Sub-Saharan Africa. The incorporation of organic residues could increase nutrient mineralization and replenish soil carbon (C), however, the effect that long-term residue management (10+ years) has on maize (Zea mays L.) yields and soil nutrient pools (C and N) is largely unknown. In four identical long-term trials in Kenya that differ by soil type and climate, we compared maize yield and soil C (0–0.15 m) across four treatments comparing organic inputs of contrasting C:N ratios: tithonia [Tithonia diversifolia (Hemsl.) A. Gray] + N (120 kg N ha−1); tithonia − N (0 kg N ha−1); maize stover + N (120 kg N ha−1); maize stover − N (0 kg N ha−1). On average, maize yields were 92% greater under tithonia compared to maize stover at the sandy sites and in general followed this trend: tithonia + N > tithonia − N = stover + N > stover − N. The continuous application of tithonia also increased soil C and N pools; for instance, mineralizable C was up to 57% greater than that of maize stover at the sandy sites. Increases in yield and nutrient pools under tithonia were less apparent at the clay sites. When exploring the relationship between soil C and maize yield, we found that both mineralizable and processed pools were related to agronomic performance. Our findings demonstrate that low C:N residues could significantly benefit crop production and enhance soil organic matter at sandy sites across Kenya.

Maize crop nutrient input requirements for food security in sub-Saharan Africa

Nutrient limitation is a major constraint in crop production in sub-Saharan Africa (SSA). Here, we propose a generic and simple equilibrium model to estimate minimum input requirements of nitrogen, phosphorus and potassium for target yields in cereal crops under highly efficient management. The model was combined with Global Yield Gap Atlas data to explore minimum input requirements for self-sufficiency in 2050 for maize in nine countries in SSA. We estimate that yields have to increase from the current ca. 20% of water-limited yield potential to approximately 50–75% of the potential depending on the scenario investigated. Minimum nutrient input requirements must rise disproportionately more, with N input increasing 9-fold or 15-fold, because current production largely relies on soil nutrient mining, which cannot be sustained into the future.