International Fertilizer Development Center

Soil fertility depletion, spatially variable nutrient limitations, and increasing climate variability are major constraints to crop productivity and resource conservation in Sub‑Saharan Africa (SSA). Sustainable nutrient management strategies that simultaneously improve crop yields, enhance soil health, and reduce nutrient losses are urgently needed to strengthen agricultural resilience. This study presents an integrated modelling framework for quantifying gaps in nitrogen (N), phosphorus (P), and potassium (K) fertilization under water‑limited conditions. The aim is to support site‑specific nutrient recommendations that improve fertilizer use efficiency while contributing to soil and water conservation.The framework combines three complementary models. INITIATOR simulates soil nutrient stocks and flows, providing a spatially explicit assessment of nutrient availability and potential depletion risks. WOFOST estimates water‑limited maize yield potential, capturing the influence of rainfall variability and soil moisture dynamics on attainable production. QUEFTS then models nutrient uptake and yield responses, enabling calculation of nutrient requirements that match crop demand without excess application. Together, these components enable a holistic evaluation of nutrient management in soil–crop–water systems on different management levels.The approach was applied to Uganda, a country characterized by strong agro‑ecological diversity, high interannual rainfall variability, and widespread soil degradation. Using 1 km resolution SoilGrids data and climate records from 2001–2024, spatially explicit water‑limited yield potentials were simulated for maize across the country. Fertilizer requirements were calculated based on median attainable yields for the period . Results reveal substantial geographic variation in nutrient availability, nutrient use efficiency, and fertilizer needs. In many areas, low soil nutrient stocks combined with high potential yield estimates lead to large fertilization gaps, while in other regions the gap is smaller due to relatively higher soil fertility or lower potential yields due to moisture constraints.These findings demonstrate that uniform fertilizer recommendations are unlikely to be effective under the diverse soil and climatic conditions of SSA. The proposed modelling framework provides a robust decision‑support tool for developing precision nutrient management strategies that align nutrient inputs with both crop demand and water availability. Such targeted approaches can help reduce nutrient losses to the environment, maintain soil fertility, and support sustainable intensification efforts across smallholder farming systems. This work highlights the potential of integrated soil–crop–climate modelling to guide context‑appropriate nutrient management solutions that enhance productivity while promoting soil and water conservation.

Phosphate rock (PR) is the key raw material in phosphatic fertilizers. However, the phosphorus (P) in PR is generally unavailable for crop nutrition. Currently, direct application of PR (DAPR) to crops accounts for less than 1% of the global annual P consumption of 21.4 million metric tons (Mt) of P equivalent. This paper reviews the International Fertilizer Development Center’s (IFDC) fifty years of research on DAPR as an alternative or supplement to water-soluble phosphate (WSP) fertilizers in acidic soils of the sub-humid and humid tropics. It highlights the significant advancements IFDC made in identifying basic principles determining the effectiveness of PR fertilizers including mineralogy, chemical reactivity, surface area and influential soil and crop factors. It also summarizes agronomic outcomes and identified economic factors impacting PR use. Examples of the use of the PR decision support system (PRDSS) developed by IFDC to integrate soil, crop, PR source and site factors to predict the relative agronomic effectiveness (RAE) and economic feasibility of the PR source are presented. Finally, the paper summarizes specific farming strategies and ongoing research that will influence the direct application of PR in the future.

Rescue in vitro maturation (rescue-IVM) refers to the post-retrieval culture of immature oocytes - typically at the germinal vesicle (GV) or metaphase I (MI) stage - under laboratory conditions, allowing them to complete maturation to metaphase II (MII) and become suitable for fertilization.This case report presents a successful pregnancy following rescue-IVM and preimplantation genetic testing for aneuploidy (PGT-A) in a 35-year-old woman with unexplained infertility and a history of ectopic pregnancy.Immature GV-stage oocytes retrieved during in vitro fertilization (IVF) were cultured using standard protocols, and several progressed to MII without pharmacologic stimulation. Following delayed intracytoplasmic sperm injection (ICSI), two euploid blastocysts were obtained, one of which led to a viable singleton pregnancy.This case underscores the clinical relevance of rescue-IVM in IVF cycles with high proportions of immature oocytes, particularly in patients with diminished ovarian reserve or tubal factor infertility. It highlights the importance of individualized assisted reproductive technology (ART) strategies, and the potential of advanced embryology techniques - such as time-lapse monitoring and optimized ICSI timing - to improve outcomes in poor-prognosis cases.

Using household consumption data collected in 2017/18, this paper analyzes patterns of urban and rural food consumption in Senegal. We adopt two methodological approaches: an in-depth (spatial) profiling of current diets and corresponding nutrient intakes and an application of the Quadratic Almost Ideal Demand System (QUAIDS). Our findings indicate that Senegal is a typical case of micronutrient deficiency, especially regarding calcium, iron, and vitamin B12. Due to their higher income status and better food access, urban dwellers on average have a more diversified diet with higher nutrient intakes compared to their rural counterparts, especially regarding calcium, vitamin B12, and vitamin A. While the country’s food system in general is unable to assure a nutritious diet for all, the most remote rural departments in Senegal, such as Saraya and Podor, display the highest nutrient deficiencies and therefore should be targeted with priority. Apart from geographical targeting and given their higher responsiveness to price and income changes, policies based on food pricing and income transfers should be implemented to ensure a minimal nutrient intake among the most food-insecure households. These policies could be further complemented with behavioral change campaigns to promote an alternative set of nutrient-rich and cost-effective food items.

The coastal zone of The Gambia, which contributes 36% to the country’s GDP, has experienced considerable transformation due to increased socioeconomic development and urbanisation. This growth has significantly altered the coastal landscape, intensifying pressure on the environment and increasing vulnerability to climate hazards. A study used cloud-free Landsat imagery from 1990, 2000, 2010, and 2020 for assessing land use and land cover (LULC) changes and population growth. The analysis classified LULC into five categories: barren land, built-up areas, vegetation cover, water bodies, and wetlands. The findings highlighted dramatic changes in LULC over the past three decades. Barren land increased by 46%, and built-up areas surged by 680%. In contrast, vegetation cover decreased by 35%, water bodies by 31%, and wetlands by 14%. These transformations correlate with rising population densities along the coastline, particularly within 10–25 km of the shore. The substantial growth in built-up areas and reduction in vegetation are directly linked to urbanisation and population pressure. This rapid change exacerbates the vulnerability of coastal communities to extreme weather events such as flooding and tropical windstorms. To address these challenges, it is crucial for the government and stakeholders to implement policies that manage coastal congestion and encourage development in inland regions. Such measures should consider the impacts of population growth on coastal environments and aim to ensure the long-term sustainability of The Gambia’s coastal ecosystems by mitigating risks associated with climate change.

Food insecurity in sub-Saharan Africa is partly due to low staple crop yields, resulting from poor soil fertility and low nutrient inputs. Integrated soil fertility management (ISFM), which includes the combined use of mineral and organic fertilizers, can contribute to increasing yields and sustaining soil organic carbon (SOC) in the long term. Soil-crop simulation models can help assess the performance and trade-offs of a range of crop management practices including ISFM, under current and future climate. Yet, uncertainty in model simulations can be high, resulting from poor model calibration and/or inadequate model structure. Multi-model simulations have been shown to be more robust than those with single models and help understand and reduce modelling uncertainty. In this study, we aim to perform the first multi-model comparison for long-term simulations of crop yield and SOC and their feedbacks in SSA. We evaluated the performance of 16 soil-crop models using data from four long-term maize experiments at sites in SSA with contrasting climates and soils. Each experiment had four treatments: i) no exogenous inputs, ii) addition of mineral nitrogen (N) fertilizer, iii) use of organic amendments, and iv) combined use of mineral and organic inputs. We assessed model performance in two steps: through blind calibration involving a minimum level of experimental data provided to the modeling teams, and subsequently through full calibration, which included a more extensive set of observational data. Model ensemble accuracy was greater with full calibration than blind calibration. Improvement in model accuracy was larger for maize yields (nRMSE 48 vs 18%) than for topsoil SOC (nRMSE 22 vs 14%). Model ensemble uncertainty (defined as the coefficient of variation across the 16 models) increased over the duration of the long-term experiments. Uncertainty of SOC simulations increased when organic amendments were used, whilst uncertainty of yield predictions was largest when no inputs were applied. Our study revealed large discrepancies among the models in simulating i) crop-to-soil feedbacks due to uncertainties in simulated carbon coming from roots, and ii) soil-to-crop feedbacks due to large uncertainties in simulated crop N supply from soil organic matter decomposition. These discrepancies were largest when organic amendments were applied. The results highlight the need for long-term experiments in which root and soil N dynamics are monitored. This will provide the corresponding data to improve and calibrate soil-crop models, which will lead to more robust and reliable simulations of SOC and crop productivity, and their interactions.

Management of nitrogen (N) fertilizer and irrigation can play a critical role to increase nitrogen use efficiency (NUE). However, the impacts of N application at the root zone via urea briquette deep placement (UDP) and water-saving irrigation alternate wetting and drying (AWD) on N2O emissions are not well-understood. A greenhouse study was conducted to investigate the impacts of UDP on N2O emissions, NUE, and grain yields of rice and wheat compared with broadcast prilled urea (PU). For rice, the effect of UDP was evaluated under continuous flooding (CF) and AWD, while the control (no N) and PU were tested only under CF. In rice, UDP under CF irrigation produced similar emissions to PU-CF, but UDP under AWD irrigation increased emissions by 4.5-fold compared with UDP under CF. UDP under CF irrigation increased (p < 0.05) rice grain yields and N recovery efficiency (RE) by 26% and 124% compared with PU-CF, respectively. In wheat, UDP had no effects (p > 0.05) on emissions compared with PU. However, it produced higher wheat grain yields (9%) and RE (35%) over PU. In conclusion, UDP under CF irrigation increases the RE and grain yields of rice without increasing N2O emissions, but the yield may reduce and N2O emissions may increase under AWD.