Options for sustainable agricultural intensification in maize mixed farming systems : explorative ex-ante assessment using multi-agent system simulation

Nutrient depletion is a major limiting factor to agricultural sustainability in cereal dominated smallholder farming systems in Africa where over 80% of arable land is unsuitable to support primary productivity. This constrains food and nutritional security of rural communities. For appropriate design of interventions, there is need for empirical evidence on drivers of change. A common sampling frame is used to integrate social-ecological data from farm surveys of soil, biomass and crop yield, nutrient inputs and outputs, and their determinants. The nutrient distributions are predicted using randomForest machine learning algorithm in R with remotely sensed reflectance for topography (30 m STRM-DEM), vegetation and soil (10 m Sentinel2 imagery) as co-variates. We use behavioural economics to unravel farm-type specific drivers of human induced nutrient inputs and a mixed model for crop yield function for outputs. Further, existing nutrient stoichiometry and transfer functions based on NUTMON, FarmDESIGN models with parameters from the study region are used to capture dynamic stocks and flows. Lastly, we build a multi-agent system for simulating sustainable agricultural intensification (MASSAI) in NetLogo and piloted to explore, ex ante, the agentic behaviours of farmers when faced with ambiguity in fertilizer subsidy regimes and its implications on nutrient budgets, human decision making and land productivity. Though soil management in smallholder farming systems aims at addressing the most critical nutrient(s), the results from this study show that the soils are deficient in all three major nutrients (NPK) and structurally unstable due to low soil organic carbon (SOC). Farmers strive to utilise the commonly available soil fertility management: nine in every ten households used inorganic fertilizers, a third integrated legumes and almost half applied manures of various forms. From the empirical and simulated results, it is indicative that the maize mixed smallholder farming system in Malawi has become inelastic to changes in input policies. Much as improvement in contribution of women in decision-making widens the scope for legume cropping, it negatively affects manuring. Therefore, addressing challenges that women face in manuring could offer greater opportunities for integrated soil fertility management. After 15 years of fertilizer subsidy program, farmers have internalized it in their expenditure plan: some exclusively relying on subsidy while others source increasing amounts from the market and are becoming self-reliant. Those that rely on limited fertilizer acquired through subsidy proactively reduce the nutrient gap by increasing manuring. These behaviors have implications on nutrient management and sustainability of the farming systems. Although subsidy alone might not significantly shift the nutrient and productivity trajectories for the next 20 simulated years, increased subsidy could relatively accelerate nitrogen and phosphorus losses.Optionen für eine nachhaltige landwirtschaftliche Intensivierung in gemischten Maisanbausystemen : explorative ex-ante-Bewertung mit einer multi-agenten-Systemsimulation Nährstoffverarmung ist ein wesentlicher limitierender Faktor für die landwirtschaftliche Nachhaltigkeit in Getreide-dominierten kleinbäuerlichen Anbausystemen in Afrika, wo mehr als 80% des Ackerlandes für die Primärproduktion ungeeignet ist. Dies schränkt die Nahrungsmittel- und Ernährungssicherheit der ländlichen Gemeinden ein. Um dem gezielt durch Interventionen entgegenwirken zu können, sind empirische Studien über Einflussfaktoren, die zu Veränderung beitragen können, nötig. Eine integrierte Stichprobenstrategie wird verwendet, um sozio-ökologische Daten aus Betriebserhebungen zu Boden, Biomasse und Ernteerträgen, Nährstoffein- und -austrägen und deren Bestimmungsfaktoren zu integrieren. Nährstoffverteilungen werden unter Verwendung des ‚randomForest- machine learning algorithm‘ in R, mit aus Fernerkundung stammenden Daten, für die Co-Variablen Topographie (30 m STRM-DEM), Vegetation und Boden (10 m Sentinel2-Bilder) simuliert. Verhaltensökonomische Ansätze geben Aufschluss über die betriebstypspezifischen Faktoren, die eine Rolle spielen, wenn es um gezielte Nährstoffeinträge durch den Menschen geht. Ein gemischtes Modell wird für die Ermittlung einer Ernteertragsfunktion verwendet, um die Erträge zu ermitteln. Darüber hinaus werden vorhandene Nährstoffstöchiometrie- und Transferfunktionen basierend auf den NUTMON und FarmDESIGN Modellen mit Parametern aus der Untersuchungsregion verwendet, um dynamische Nährstoffbestände und -Flüsse zu erfassen. Schließlich bauen wir in NetLogo ein Multi-Agenten-System zur Simulation einer nachhaltigen Intensivierung der Landwirtschaft (MASSAI) auf und untersuchen, ex ante, das Verhalten von Landwirten, die aufgrund eines Düngemittelsubventionssystems mit Unklarheiten konfrontiert werden und dessen Auswirkungen auf Entscheidungsprozesse, Nährstoffbudgets und Landproduktivität. Wenngleich Bodenbewirtschaftung in kleinbäuerlichen Anbausystemen darauf abzielt, Defizite in den kritischsten Nährstoffen auszugleichen, zeigen die Ergebnisse dieser Studie, dass die Böden in allen drei Hauptnährstoffen (NPK) mangelhaft und aufgrund niedriger organischer Kohlenstoffgehalte im Boden strukturell instabil sind. Landwirte streben an, allgemein verfügbare Methoden für Bodenfruchtbarkeitsmanagement zu nutzen: neun von zehn Haushalten verwendeten anorganische Düngemittel, ein Drittel integrierte Leguminosen und fast die Hälfte brachten Mist verschiedenster Art aus. Die empirischen und simulierten Ergebnisse deuten darauf hin, dass das gemischte kleinbäuerliche Maisanbausystem in Malawi gegenüber Veränderungen in politischen Richtlinien, die den Einsatz von Betriebsmitteln betreffen, unelastisch geworden ist. Die verbesserte Einbindung von Frauen in Entscheidungsprozesse macht zwar den Anbau von Leguminosen wahrscheinlicher, wirkt sich jedoch negativ auf den Einsatz von Mist aus. Daher könnte sich die Bewältigung von Herausforderungen, denen Frauen beim Düngen ausgesetzt sind, positiv auf ein integriertes Bodenfruchtbarkeitsmanagement auswirken. Nach 15 Jahren Düngersubventionen haben die Landwirte diese fest in ihre Budgetplanung integriert, wobei sich einige ausschließlich auf Subventionen verlassen, während andere mit eigenen Einkäufen mischen und nicht-Subventionsempfänger zunehmend Dünger über den Markt beziehen. Diejenigen die auf begrenzten, durch Subventionen erworbenen Dünger angewiesen sind, verringern proaktiv die Nährstofflücke durch Mistgaben. Diese Verhaltensweisen haben Auswirkungen auf das Nährstoffmanagement und die Nachhaltigkeit der landwirtschaftlichen Systeme. Obwohl Subventionen allein die Nährstoff- und Produktivitätsverläufe für die simulierten nächsten 20 Jahre möglicherweise nicht wesentlich verändern, könnten erhöhte Subventionen die Stickstoff- und Phosphorverluste beschleunigen

The indirect impact of crop insurance on household food security in the Guinea savannah region of West Africa

Under high climatic, disease and market uncertainty, smallholder farmers make heuristic decisions on whether to manage risk and invest in profitable alternatives or, as a risk-averse mechanism, continue with the traditional low-risk low-return practices. The goal of this paper is to investigate the role of information, social capital, and resource endowments on farmers' decision to invest in insurance bundled with fertilizer and modern improved seeds and its impacts on food security indicators including surplus produce, marketing share, and produce storage. Results show that insurance induces a 113% increase in the proportion of maize sold and an increased probability to keep food reserves for the lean period by 42%. Impacts of insurance on marketing and storage are contingent on cropping system, agro-advisory and resource endowments with differentiated effects. These findings reveal that bundling crop insurance with high-cost productivity improving inorganic fertilizers and modern improved varieties bred for drought tolerance is a viable option for farmers to make risky productivity-enhancing investments and improve livelihoods that contribute economic development and food security

Soil structural degradation and nutrient limitations across land use categories and climatic zones in Southern Africa

Although soil degradation is a major threat to food security and carbon sequestration, our knowledge of the spatial extent of the problem and its drivers is very limited in Southern Africa. Therefore, this study aimed to quantify the risk of soil structural degradation and determine the variation in soil stoichiometry and nutrient limitations with land use categories (LUCs) and climatic zones. Using data on soil clay, silt, organic carbon (SOC), total nitrogen (N), available phosphorus (P), and sulfur (S) concentrations collected from 4,468 plots on 29 sites across Angola, Botswana, Malawi, Mozambique, Zambia and Zimbabwe, this study presents novel insights into the variations in soil structural degradation and nutrient limitations. The analysis revealed strikingly consistent stoichiometric coupling of total N, P, and S concentrations with SOC across LUCs. The only exception was on crop land where available P was decoupled from SOC. Across sample plots, the probability (φ) of severe soil structural degradation was 0.52. The probability of SOC concentrations falling below the critical value of 1.5% was 0.49. The probabilities of soil total N, available P, and S concentrations falling below their critical values were 0.95, 0.70, and 0.83, respectively. N limitation occurred with greater probability in woodland (φ = .99) and forestland (φ = .97) than in cropland (φ = .92) and grassland (φ = .90) soils. It is concluded that soil structural degradation, low SOC concentrations, and N and S limitations are widespread across Southern Africa. Therefore, significant changes in policies and practices in land management are needed to reverse the rate of soil structural degradation and increase soil carbon storage

Reducing smallholder farmers’ risk through agricultural advisories and climate smart agriculture in Northern Ghana

AICCRA baseline data was collected from target populations that were previously engaged in CCAFS and counterfactual communities from 6 regions of Ghana and 4 ecological zones namely: Transition, Coastal Savannah, Guinea Savannah, and Sudan Savannah (MAP). The counterfactual communities from 6 regions of Ghana included Greater Accra, Central, Upper East, Upper West, Bono East, and Northern Regions. Both Climate Information Services (CIS) and Climate Smart Agriculture (CSA) demands vary across different ecoregions with respect to variations in climatic suitability/limitations, farming systems, cultural norms, and livelihood strategies. The socio-ecological differences have strong bearing on men’s and women’s mitigation and adaptive responses

Spatial Variation in Tree Density and Estimated Aboveground Carbon Stocks in Southern Africa

Variability in woody plant species, vegetation assemblages and anthropogenic activities derails the efforts to have common approaches for estimating biomass and carbon stocks in Africa. In order to suggest management options, it is important to understand the vegetation dynamics and the major drivers governing the observed conditions. This study uses data from 29 sentinel landscapes (4640 plots) across the southern Africa. We used T-Square distance method to sample trees. Allometric models were used to estimate aboveground tree biomass from which aboveground biomass carbon stock (AGBCS) was derived for each site. Results show average tree density of 502 trees·ha−1 with semi-arid areas having the highest (682 trees·ha−1) and arid regions the lowest (393 trees·ha−1). The overall AGBCS was 56.4 Mg·ha−1. However, significant site to site variability existed across the region. Over 60 fold differences were noted between the lowest AGBCS (2.2 Mg·ha−1) in the Musungwa plains of Zambia and the highest (138.1 Mg·ha−1) in the scrublands of Kenilworth in Zimbabwe. Semi-arid and humid sites had higher carbon stocks than sites in sub-humid and arid regions. Anthropogenic activities also influenced the observed carbon stocks. Repeated measurements would reveal future trends in tree cover and carbon stocks across different systems

Ghana planning and implementation progress report for the CGIAR Initiative on Sustainable Intensification of Mixed Farming Systems

This report captures key outputs, and follow-up actions since the Ghana Country Planning and Inception Meeting for the Sustainable Intensification of Mixed farming Systems Initiative was held in Accra, Ghana, on 12 July 2022. Various partners have been engaged in the Initiative in Ghana so far, including the National Agricultural Research and Extension Systems (NARES), Universities, and National governments/ agricultural administrations (See participants list in Annex)

Divergent climate smartness priority setting by practitioners vis-à-vis advisors: implications on inclusivity, one-health achievement, and enabling environment

By capturing the prioritization of 22 innovations by 71 farmers against those of advisors, this paper examines the level of awareness and contextualized conceptualization of 31 indicators of Climate Smartness Plus (equity, one health and enabling environment). Concordance analysis reveals differences in prioritization among farmers and agricultural advisors: with advisors giving relatively higher ratings as they set broader goals than farmers. We find that farmers give equal priority to productivity, adaptation, and mitigation while advisors overly prioritise productivit

The impact of participatory action research and endogenous integrated soil fertility management on farm-gate dietary outputs in Northern Tanzania

In most developing countries, although agricultural extension and research devolved since 1980s to promote relevance, cost-effectiveness, ownership, and sustainability, participatory action research (PAR) have been run, albeit with limited empirical evidence on their impacts on farmers livelihoods. The study use a three-stage extended regression model (ERM) to estimate the effect PAR and the promoted agronomic practices on crop produce dietary outputs considering potential endogenous engagement, omitted variable bias, reverse causality, endogenous covariates, and factor simultaneity. Using a sample of 607 small family farms with varying levels of research engagement in the Northern Highlands of Tanzania, the study found that PAR was associated with increased farm-gate dietary outcomes: per-capita calories, proteins, and minerals produced by 139, 216, and 143 %, respectively, and consumption of farm-produced minerals by 74–200 %. The organic manure application was associated with increased the dietary outputs by 62–113 % while the application of inorganic fertilizer with increased protein and mineral outputs by 68 and 105 %, respectively. The crop diversification was associated with increased dietary outputs by 11–25 % while pest and diseases control with increased dietary outputs by 12–17 % but with reduced consumption by 13–14 %. Soil and water conservation measures including terracing were associated with decreased dietary outputs. These findings indicate that PAR contributes to nutritional outcomes of smallholder farmers contingent on the promotion of low-cost input sources and crop diversification which can be leveraged to inform upscaling of participatory policies, strategies, and technologies