Evaluation of Suitability of Some Soils in the Forest-Savanna Transition and the Guinea Savanna Zones of Ghana for Maize Production

Suitability of four soils located in the Forest-Transition zone and four others located in the Guinea Savanna zone of Ghana were evaluated for maize production using Soil Quality Index (SQI), Decision Support System for Agrotechnology Transfer (DSSAT) yield simulations and the Multi-Criteria Analysis (MCA).  Wenchi (Ferric Dystric Leptosol), Ejura (Haplic Lixisol), Damongo (Dystric Nitisol) and Lima series (Eutric Gleysol) were located in the Forest-Savanna Transition agro-ecological zone whereas Kpelesawgu (Eutric Plinthosol), Varempere (Ferric Luvisol), Mimi (Haplic Lixisol) and Kupela (Eutric Gleysol) series were located in the Guinea Savanna agro-ecological zone. The study sites in the Forest-Savanna zone were located in the Brong-Ahafo region whereas those in the Guinea Savanna zone were in the Northern region of Ghana. Properties used for the SQI rating included bulk density, pH, organic carbon, total nitrogen, available phosphorus, texture and water holding capacity. For the DSSAT, 1980 – 2010 weather variability impacts in addition to soil and management effects were used. The MCA evaluation included factors such as price, input and labour costs, distance to market, soil erosion and conservation factors. The three approaches gave different rankings of the soils for maize production. The SQI results rated the soils in the order: Wenchi > Damongo > Mimi > Ejura > Kupela > Lima > Varempere > Kpelesawgu. From the DSSAT simulations, the order was Varempere > Kpelesawgu > Damongo > Ejura > Kupela > Mimi > Lima > Wenchi. From the MCA, the rankings under different soil management options was in the order: Damongo > Mimi > Ejura > Wenchi > Lima > Varempere > Kupela > Kpelesawgu. Whereas both the SQI and the MCA ranked Kpelesawgu series as the least suitable for maize production, the DSSAT ranked it as the second most suitable. From the results, soils in the Forest-Savanna Transition zone were more suitable for maize production than those in the Guinea Savannah zone. Soils with negligible gravel content could generally be considered as more suitable for intensive maize production. Although the SQI and the DSSAT yield simulations gave less desirable outcomes than the MCA simulations, they should be considered as useful basis for evaluating and designing the MCA criteria

Using CERES-maize and ENSO as decision support tools to evaluate climate-sensitive farm management practices for maize production in the northern regions of Ghana

Open Access JournalMaize (Zea mays) has traditionally been a major cereal staple in southern Ghana. Through breeding and other crop improvement efforts, the zone of cultivation of maize has now extended to the northern regions of Ghana which, hitherto, were the home to sorghum and millet as the major cereals. Maize yield in the northern Ghana is hampered by three major biophysical constraints, namely, poor soil fertility, low soil water storage capacity and climate variability. In this study we used the DSSAT crop model to assess integrated water and soil management strategies that combined the pre-season El-Niño-Southern Oscillation (ENSO)-based weather forecasting in selecting optimal planting time, at four locations in the northern regions of Ghana. It could be shown that the optimum planting date for a given year was predictable based on February-to-April (FMA) Sea Surface Temperature (SST) anomaly for the locations with R2 ranging from 0.52 to 0.71. For three out of four locations, the ENSO-predicted optimum planting dates resulted in significantly higher maize yields than the conventional farmer selected planting dates. In Wa for instance, early optimum planting dates were associated with La Nina and El Niño (Julian Days 130-150; early May to late May) whereas late planting (mid June to early July) was associated with the Neutral ENSO phase. It was also observed that the addition of manure and fertilizer improved soil water and nitrogen use efficiency, respectively, and minimized yield variability, especially when combined with weather forecast. The use of ENSO-based targeted planting date choice together with modest fertilizer and manure application has the potential to improve maize yields and also ensure sustainable maize production in parts of northern Ghana

Mode of Biochar Application to Vertisols Influences Water Balance Components and Water Use Efficiency of Maize (Zea mays L.)

Vertisols belong to a group of soils with high fertility but poor physical properties of swelling when wet and shrinking and cracking when dry. The swelling inhibits infiltration, resulting in flooding, limiting the production of upland crops. Biochar (<BC) application has been shown to reduce the shrink-swell behaviour of Vertisols. However, the mode of biochar application to these soils may affect the effectiveness of the amendment. This study investigated the water relations and maize (Zea mays L.) growth under two BC application modes: (i) biochar applied into cracks that develop with drying, C, and (ii) biochar that was surface broadcast and incorporated into the topsoil, FM. A control treatment did not receive any BC amendment. Maize was grown on the BC-amended Vertisols using the two modes of application in a greenhouse under two seasonal water regimes of 610 and 450 mm. The results showed that the proportion of total water application lost to runoff was 37%, 49% and 53% for C, FM and control treatments, respectively. Both maize yield and Water Use Efficiency (WUE), for the C treatments were significantly (p < 0.05) higher than those for FM treatments. The maize yield under the C treatments was 19% over the control. Similarly, the WUE for the C treatments was 28% above the control treatment. It is concluded that the application of biochar into cracks is a more effective way of improving the water relations and upland crop productivity and WUE in Vertisols than the traditional surface incorporation

Influence of Method of Residue Application and Moisture Content on Water Soluble Nitrogen in a RhodicKandiustalf Amended with Different Fallow Plant Materials

Use of plant residues as nutrient sources presents a viable option to resource poor farmers who sparsely use mineral fertilizer in crop production. A study was conducted to gain an insight into how different application methods of residues from different fallow management systems under two moisture regimes would affect soluble N release in a Rhodic Kandiustalf. Three residue types viz, elephant grass from a natural fallow (T1) and another as a fallow following a previously fertilized maize (T2) and a fallow legume (T3) were surface applied and incorporated in a Rhodic Kandiustalf at both field capacity (FC) and 60% field capacity over a sixteen-week period. Incorporation of mucuna residues and elephant grass from previously fertilized maize fallow released similar soluble N levels which were higher than levels from the natural elephant grass amendments. At 60% FC, both mucuna and elephant grass from the fertilized maize fields that were surface applied had slower N releases than the grass from the natural fallow, suggesting the elephant grass from the natural fallow field could be used as an N source amidst light watering to avoid leaching in the dry season

Weather-index based crop insurance as a social adaptation to climate change and variability in the Upper West Region of Ghana: Developing a participatory approach

Climate change and variability are major challenges to rain-fed crop production in Africa. This paper presents a report on a pilot project to test a concept for operationalizing weatherindex crop insurance as a social adaptation to the climate change and variability problem in the Upper West Region of Ghana. An analysis of long-term weather variables showed rising temperature of 1.7 oC over a period of 53 years as well as major shifts in rainfall patterns. Farmers face a new reality that cannot be addressed with their indigenous knowledge alone. The weather-index based crop insurance concept discussed herein was developed by combined effort of University of Ghana, the German International Cooperation (GIZ) and the Ghana National Insurance Commission (NIC) since 2010. This development was carried out via their filial, the Ghana Agricultural Insurance Pool (GAIP). The proposed concept sought to link various agricultural stakeholders such weather technical persons, farmers, agricultural extension officer, input dealers and other aggregators, and financial institutions as well as the insurance industry and focused on a participatory farmer led approach. The piloting of the concept was supported by the Climate Change and Food Security (CCAFs) project and was tested in the years 2012 and 2013 using a theatrical drama sketch in two districts in the Upper West Region of Ghana: Jirapa and Lawra. It was observed that training of farmers in the basic principles of weather (data collection, interpretation, etc.) facilitated the discussions on drought insurance, adding to the body of evidence supporting participatory design tools. The aim of this paper is to record this process and to put the results into recent context, through discussing them through the lens of insurance operations and research in Ghana. Ensuing discussions showed that although all stakeholders considered the participatory design tools to be meritorious, a number of logistical challenges were identified that need to be addressed for effective scaling. The study also highlighted the high spatial variability of rainfall in the Upper West region of Ghana, showing the necessity of satellite-derived rainfall products. Finally, the framework suggested in this report highlights the complexity and the institutional structures required to implement an effective insurance. In effect, our simple study has exposed the complexities and intricacies that must be overcome in establishing a sustainable insurance scheme in Ghana

Location and Land use effects on Soil Carbon Accretion and Productivity in the Coastal Savanna Agro-ecological Zone of Ghana

Land use type, climate and soil properties are major determinants of soil carbon storage and productivity, especially in low-input agriculture. In this study, we investigated the interactions among these factors at four (4) locations, namely Accra Metropolis, Ga West, Ga East and Shai Osudoku, within the Coastal-Savannah agro-ecological zone of Ghana. The land use types were maize-based cropping, cassava-based cropping, woodlot/plantations and natural forests. The impact of these on soil productivity at a given location was assessed in terms of soil carbon stocks and a Soil Productivity Index (SPI). The SPI is a composite value derived from routine soil properties such as: soil texture, available water capacity, pH, cation exchange capacity, soil organic carbon, available P, exchangeable K, potentially mineralizable nitrogen, and basic cations, among others. Principal component analysis was used to select soil properties that were used to estimate SPI. The results showed that the locations differed with respect to rainfall regimes and soil types. Locations with slightly heavier soil texture and relatively higher rainfall regimes (Ga East and Shai Osudoku) had significantly higher soil carbon storage and SPI values than the lighter soil textured locations (Accra Metropolis and Ga West). With regards to land use, forest had significantly higher soil carbon storage and SPI than all the other land use types, irrespective of location. The order of soil carbon storage and SPI were: forest > woodlot/plantation > cassava > maize. It was observed that though the Accra Metropolis location hosted the oldest forest, soil carbon was still low, apparently due to the lighter soil texture. We concluded that the soil productivity restorative ability is an interactive effect of carbon management (land use), soil texture and other properties. This interaction hitherto has not been adequately investigated, especially in low-input agriculture

Evaluating maize yield variability and gaps in two agroecologies in northern Ghana using a crop simulation model

Article purchased; Published online: 19 Oct 2017The yield gap and variability in maize under smallholder systems in two agroecologies in northern Ghana were evaluated using a decision support system for agrotechnology transfer (DSSAT). The model was used to assess (1) the potential yield of maize (YPOT), (2) water-limited exploitable maize yield (YWEX), (3) nitrogen-limited yield (YNI), (4) farmer practice maize yield (YCFP) and (5) proposed enhanced nutrient use yield (enhanced farmer practice; YEFP). Effect of supplementary irrigation was also assessed on YCFP and YEFP conditions. Yield gaps were determined as the difference between YPOT and YCFP or YEFP on the one hand, and between YWEX and YCFP or YEFP on the other hand. The yield gap based on potential yield ranged from 59% to 75% under CFP and narrowed to between 29% and 59% under EFP. With water-limited exploitable yields, the yield gap ranged from 53% to 65% under CFP, reducing to between 22% and 42% under EFP. The use of supplementary irrigation further reduced the yield gap. Improved fertiliser use and supplementary irrigation have the potential to increase yield and hence reduce the yield gap if effective policies and institutional structures are in place to provide farmers with credit facilities and farm inputs

Productivity of Soybean under Projected Climate Change in a Semi-Arid Region of West Africa: Sensitivity of Current Production System

The production of soybean is gaining more attention in West Africa. In light of projected changes in climate, there is a need to assess the potential impacts on yield productivity and variability among farmers. An evaluated GROPGRO module of the Decision Support System for Agro-technological Transfer (DSSAT) was used to simulate soybean productivity under both historical (1980–2009) and projected climate scenarios from multiple general circulation models (GCMs) under two representative concentration pathways (RCPs): 4.5 and 8.5. Agronomic data from 90 farms, as well as multiple soil profile data, were also used for the impact assessment. Climate change leads to a reduction (3% to 13.5% across GCMs and RCPs) in the productivity of soybean in Northern Ghana. However, elevated atmospheric carbon dioxide has the potential to offset the negative impact, resulting in increased (14.8% to 31.3% across GCMs and RCPs) productivity. The impact of climate change on yield varied widely amongst farms (with relative standard deviation (RSD) ranging between 17% and 35%) and across years (RSD of between 10% and 15%). Diversity in management practices, as well as differences in soils, explained the heterogeneity in impact among farms. Variability among farms was higher than that among years. The strategic management of cultural practices provides an option to enhance the resilience of soybean productivity among smallholder

Auswirkungen von Biokohle, Abwasserbewässerung und Düngung auf Bodeneigenschaften unter urbaner Landwirtschaft in Westafrika

Die zunehmende nachfrageorientierte Intensivierung der Agrarproduktion im semiariden Westafrika wird aus bodenkundlicher Sicht durch geringe Bodenfruchtbarkeit und hohen Bodendegradationsraten limitiert. Als vielversprechende Möglichkeit zur Bodenverbesserung wird seit einiger Zeit Biokohle vorgeschlagen. Zudem wird im städtischen Umfeld ungeklärtes Abwasser zur Bewässerung eingesetzt. Denn Abwasser wird nicht nur als ganzjährige Wasserquelle, sondern auch als Nährstoffquelle für Böden und Pflanzen betrachtet, trotz des hohen Kontaminationsrisikos durch Pathogene und Schwermetalle. Wissenslücken bestehen vor allem bezüglich der Wechselwirkungen zwischen Biokohle, Düngung und Abwasserbewässerung und Bodeneigenschaften. Das Ziel dieser Studie war daher die Untersuchung der Auswirkungen von Biokohle (hergestellt aus Ernterückständen des Mais- und Reisanbaus), organischer und anorganischer Düngung, Bewässerungsqualität und Bewässerungsquantität auf die Bodeneigenschaften von zwei sandigen, humus- und nährstoffarmen Böden unter Gemüseanbau im urbanen Raum von Tamale (Nordghana) und Ouagadougou (Burkina Faso) über einen Zeitraum von zwei Jahren. Die Applikation von Biokohle bewirkte eine Verdoppelung der C-Vorräte auf beiden Standorten, allerdings wurden anschließend C-Verluste in Höhe von 35 % in Ouagadougou und 46 % in Tamale beobachtet. Korrigiert durch die Auswirkungen der Landnutzungsänderungen verringern sich die C-Verluste in Tamale auf ebenfalls 35 %. Beide Biokohlen hatten keine Auswirkungen auf den pH-Wert, die KAK und das verfügbare P. Die Applikation von Reishülsenbiokohle führte zur N-Retention (18 % höhere N-Vorräte im Vergleich zur Kontrolle), wohingegen die Maisspindelkohle keine Auswirkung auf den N-Haushalt hatte. In Tamale führte die NPK Düngung zur Erhöhung des verfügbaren P sowie zur Versauerung (0.65 pH-Einheiten) und zur Verringerung der effektiven Basensättigung (von nahezu 100% auf 93%) aufgrund der geringen Pufferkapazität des Bodens. In Ouagadougou führte die regelmäßige organische Düngung mit Rindermist zur Erhöhung der C- und N-Vorräte und der KAK. Die einzigen Auswirkungen der Abwasserbewässerung waren ein Anstieg des austauschbaren Natriums und des pH Wertes. Die Ergebnisse der Untersuchungen an beiden Standorten zeigen, dass die Auswirkungen von Biokohle, die aus Ernterückständen hergestellt wurde, und Abwasserbewässerung auf die Bodeneigenschaften geringer sind als in früheren Studien beschrieben wurde