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Browsing Project Reports by Author "Anselme K. K. Kouame"
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- ItemEvaluation and Geospatial Analysis of Variability in Maize Yield Response to Fertilizer (NPK) Using Modeling in Ghana(2021) Anselme K. K. Kouame; Bindraban, Prem S.; Isaac N. Kissiedu; Khalil El Mejahed; Williams K. AtakoraMaize is the main cereal crop in Ghana. However, yields are very low (around 1-1.5 mona), and despite the increase in fertilizer application per hectare (21-22 kg/ha), there are large differences in yields in on-farm and on-station trials. Maize production is hampered by several biotic and abiotic factors that negatively impact its yield response to fertilizer application. Therefore, we sought to understand why, despite fertilizer application, maize yields do not increase consistently over space and time and what major factors explain this variability. To answer this question, we chose a yield-modeling approach based on yield data from on-farm and on-station trials. Quantitative Evaluation of Fertility of Tropical Soils (QUEFTS) and Multiple Linear Regression-Akaike Information Criterion (MLR-AIC) models were used to evaluate observed yield variability, while random forest for spatial predictions framework modeling was used for geospatial analysis and mapping of yield predicted. The QUEFTS model cannot significantly explain yield variability at the station and farm level (R-12% and R-24.6%, respectively). MLR showed that soil physical properties explained more of the yield variability (R-24%) at the station level than environmental parameters (R²=8%), with chemical soil properties explaining the highest fraction (R-41%). At the farm level, environmental covariates (R2-26%) explained more variability in yield response than physical (R-21%) and soil chemical (R-16%) variables. Detailed regression analysis revealed that high temperature and high rainfall combined with shallow rooting depth (<50 cm) were determinants that reduced the effectiveness of fertilizer application. Understanding the yield variability observed in Ghana for better fertilizer recommendations must be done comprehensively because yield variability is the result of the interaction and combination of several covariates. Other covariates, such as management, pest and diseases, and solar radiation, must be considered in further modeling analysis
- ItemFerari Research Demonstrates Addition of Sulphur to NPK Increases Maize Yields in Ghana(2023-07) Bindraban, Prem S.; Williams K. Atakora; William Adzawla; Anselme K. K. Kouame; Michael Asante; Vincent Kodjo Avornyo; Mohamed El Gharous ; Raphael Adu-Gyamfi ; Akua Foriwaa Kwarteng; Patrick Ofori; Hulda SakyiThis study, conducted by FERARI examines the impact of sulfur addition to NPK (Nitrogen, Phosphorus, and Potassium) fertilizers on maize yields in Ghana. Over a span of three years, from 2020 to 2022, FERARI conducted more than 400 experiments on maize, soybean, and rice, collaborating with Ghanaian universities and research institutions while simultaneously providing training to students. In 2023, FERARI is in the process of validating its preliminary fertilizer recommendations based on three years of field data and legacy data from national research institutes and universities, which include over 1,000 experimental observations on maize. The experiments conducted in 2020 aimed to verify recommended NPK rates and assess the impact of additional nutrients such as zinc (Zn), sulfur (S), and iron (Fe) on crop yields. In 2021, FERARI introduced briquette technology alongside the 2020 experimental designs. Experimental sites in 2020 and 2021 were selected based on recommendations from researchers of partner institutions, encompassing on-station, on-farm, and farmer-managed experiments. In contrast, the site selection for experiments in 2022 and 2023 was based on a combination of soil properties, including organic matter content, soil depth, pH levels, and slope of the land. This approach allowed FERARI to establish experiments that accounted for the heterogeneity in soil properties and to understand the impact of fertilizer formulations on crop yields in the Guinea Savannah and Transitional zones of Ghana. The study findings indicate that optimal maize yields of around 5-7 tons per hectare can be achieved with NPK application rates somewhat below the current national recommendations. The application of sulfur in addition to NPK demonstrated a positive impact on maize yields, particularly in the Transitional Zone and Guinea Savannah. FERARI's research underscores the potential to improve maize production in Ghana, especially in the northern regions, by optimizing fertilizer application, enhancing soil quality, and addressing yield gaps. The program's efforts hold the promise of increasing maize production, improving smallholder farmer income, and advancing food security in the region
- ItemIdentifying factors that drive Yield Response of Maize to NPK Fertilization(2021-08) Anselme K. K. Kouame; Bindraban, Prem S.; Isaac N. Kissiedu; Khalil El Mejahed; Williams K. AtakoraThe yield response of maize to NPK fertilizer application in Ghana exhibits significant variability across different agroecological zones. This study, conducted by FERARI, utilizes advanced modeling and statistical methods to investigate the factors influencing these diverse yield responses. The analysis draws upon a comprehensive dataset comprising nearly 1,700 data points from both on-farm and on-station trials. Despite the substantial increase in fertilizer use in recent decades, maize yields have only seen modest improvements. This research builds upon a previous study by Buah et al. (2020) and seeks to address the critical question of why maize yield responses to fertilizer applications vary significantly. To understand this variability, two modeling approaches, Quantitative Evaluation of Fertility of Tropical Soil (QUEFTS) and Akaike Information Criterion in Multiple Linear Regression (AIC-MLR), were employed. QUEFTS, which focuses on soil fertility characteristics, explained 24.6% of yield variability in on-farm trials and 12% in on-station trials. AIC-MLR, which considers a broader range of factors including soil physical characteristics and climatic variables, provided a more comprehensive understanding, explaining 50% of yield variability. Soil physical factors accounted for 25% of variability, environmental factors 10%, and chemical soil fertility characteristics 33% in on-station trials, while environmental factors were more influential than physical and chemical factors in on-farm trials. Interestingly, the study revealed that fertilizer application increased both maize yield and yield stability. This information is particularly valuable for improving farming practices and increasing agricultural productivity in Ghana. In conclusion, this research highlights the need to consider not only soil fertility but also soil physical characteristics, climatic factors, and other variables when studying the impact of fertilizers on maize yield. The findings also underscore the potential impact of climate change on maize production in Ghana, emphasizing the importance of addressing these factors in agricultural planning and policy development.