Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Decision Support System for Site-Specific Fertilizer Recommendations in Cassava Production in Southern Togo
    Ezui, Kodjovi Senam ; Leffelaar, Peter A. ; Franke, Angelinus C. ; Mando, Abdoulaye ; Giller, Ken E. - \ 2018
    In: Improving the Profitability, Sustainability and Efficiency of Nutrients Through Site Specific Fertilizer Recommendations in West Africa Agro-Ecosystems / Bationo, Andre, Ngaradoum, Djimasbé, Youl, Sansan, Lompo, Francois, Fening, Joseph Opoku, Springer International Publishing - ISBN 9783319587912 - p. 125 - 138.
    The Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model recommended as a decision support tool for deriving optimal site-specific fertilizer rates for cassava has limited ability to estimate water-limited yields. We assessed potential and water-limited yields based on the light interception and utilization (LINTUL) modelling approach in order to enhance the determination of fertilizer requirements for cassava production in Southern Togo. Data collected in 2 years field experiments in Sevekpota and Djakakope were used. Potential ranged from 12.2 to 17.6 Mg ha−1, and water-limited yields from 10.4 to 14.5 Mg ha−1. The simulated average fertilizer requirements were 121 kg N, 2 kg P and no K ha−1 for a target yield of 9.3 Mg ha−1 at Sevekpota, and 103 kg N, 6 kg P and 175 kg K ha−1 for a target yield of 9.7 Mg ha−1 at Djakakope. The variability of fertilizer requirements was attributed to differences in indigenous soil fertility and water-limited yields. The latter correlated well with rainfall variability over years and sites. Integrating LINTUL output with QUEFTS helped account for location-specific weather seasonal variability and enhanced assessment of fertilizer requirement for cassava production in Southern Togo.
    Grazing lands in Sub-Saharan Africa and their potential role in climate change mitigation: What we do and don't know
    Milne, E. ; Aynekulu, E. ; Bationo, A. ; Batjes, N.H. ; Boone, R. ; Conant, R. ; Davies, J. ; Hanan, N. ; Hoag, D. ; Herrick, J.E. ; Knausenberger, W. ; Neely, C. ; Njoka, J. ; Ngugi, M. ; Parton, B. ; Paustian, K. ; Reid, K. ; Said, M. ; Shepherd, K. ; Swift, D. ; Thornton, P. ; Williams, S. ; Miller, S. ; Nkonya, Ephraim - \ 2016
    Environmental Development 19 (2016). - ISSN 2211-4645 - p. 70 - 74.
    In 2014, the USAID project ‘Grazing lands, livestock and climate resilient mitigation in Sub-Saharan Africa’ held two workshops, hosted by the Colorado State University, which brought together experts from around the world. Two reports resulted from these workshops, one an assessment of the state of the science, and the other an inventory of related activities in the region to date.. In this short communication we summarize the main points of the first report – The state of the science (Milne and Williams, 2015). A second report is in preparation.
    Map-based estimates of present carbon stocks of grazing lands in Sub-Sahara Africa
    Batjes, N.H. ; Milne, E. ; Williams, S. - \ 2015
    In: Grazing Lands, Livestock and Climate Resilient Mitigation in Sub-Saharan Africa: The State of the Science United States Agency for International Development (USAID) - p. 31 - 33, 97-100.
    This report is a detailed review, synthesis, and analysis of the current “state of the science” concerning the potential for carbon sequestration in grazing lands through improved land management practices in Sub-Saharan Africa (SSA). It aims to provide an up-to-date assessment of the science of C sequestration from improved land management, including the current levels of uncertainty, major gaps in knowledge and data, areas for near term research and development, major determinants of sequestration potential, and current and potential scientific monitoring tools. The report firstly gives an overview of current grazing lands in SSA (Chapter 1) and explores the major determinants of C sequestration in grass/rangeland systems (Chapter 2). It then considers current research work on C impacts of grazing land management systems (Chapter 3). Available measurement techniques are summarized in Chapter 4 and a map based approach is then used in Chapter 5 to estimate present C stocks in grazing lands in SSA. This is followed by Chapter 6 which looks at available modeling techniques and Chapter 7 which presents a model based estimate of C sequestration potential in grass/rangelands in SSA. The final chapter (Chapter 8) provides a synthesis of the report’s findings. > Authors of the respective chapters: Eleanor Milne · Stephen Williams · Andre Bationo · Robin Reid · David Swift · Rich Conant · Niall Hanan · Constance Neely · Ermias Aynekulu · Keith D. Shepherd · Niels Batjes · Randall Boone
    Soil carbon, multiple benefits
    Milne, E. ; Banwart, S.A. ; Noellemeyer, E. ; Abson, D.J. ; Ballabio, C. ; Bampa, F. ; Bationo, A. ; Batjes, N.H. ; Bernoux, M. ; Bhattacharyya, T. - \ 2015
    Environmental Development 13 (2015). - ISSN 2211-4645 - p. 33 - 38.
    In March 2013, 40 leading experts from across the world gathered at a workshop, hosted by the European Commission, Directorate General Joint Research Centre, Italy, to discuss the multiple benefits of soil carbon as part of a Rapid Assessment Process (RAP) project commissioned by Scientific Committee on Problems of the Environment (SCOPE). This collaboration led to the publication of the SCOPE Series Volume 71 “Soil Carbon: Science, Management and Policy for Multiple Benefits”; which brings together the essential scientific evidence and policy opportunities regarding the global importance of soil carbon. This short communication summarises the key messages of the assessment including research and policy implications.
    Adoptability of sustainable intensification technologies in dryland smallholder farming systems of West Africa
    Woittiez, L.S. ; Descheemaeker, K.K.E. ; Giller, K.E. - \ 2015
    ICRISAT - 87
    Within the framework of CGIAR Research Program (CRP) 1.1: Dryland Systems, the compilation of a review of options, constraints and potential for agricultural intensification at a number of specific sites in West African dryland areas has been requested, using an integrated systems approach. CRP 1.1 aims to develop technology, policy and institutional innovations to improve livelihoods, for the poor and highly vulnerable populations of the dry areas (ICARDA 2011). In the introduction to Strategic Research Theme 3 of the project, it is stated that sustainable intensification aims at increasing input use to increase output, based on agroecological principles of sustainability. The program focuses on dryland systems in West Africa identified by two criteria: (i) those with the deepest endemic poverty and most vulnerable people and (ii) those with the greatest potential to impact on food security and poverty in the short and medium term. These areas have been sampled and 10 research locations have been selected and characterized. The first output of the Strategic Research Theme 3 is defined as: Sustainable intensification options designed and developed. A range of potential options for sustainable intensification has been described previously, and multiple reviews of successful and less successful innovations for and by smallholders in Africa have been published in scientific and grey literature (Dudal, 2001; Haggblade, 2004; Aune and Bationo, 2008; FAO, 2008; Reij and Smaling, 2008; Tenywa and Bekunda, 2009; Bayala et al., 2011 Pretty et al., 2011). This report provides an overview of the current technologies, and describes four of them in detail. The potential of the technologies for increasing productivity is assessed, and an attempt is made to perform an ex ante analysis of their fit, or in other words their ‘adoptability’, within four research sites. Through this exercise, we explored the way forward, to go from ‘best bet’ to ‘best fit’ options for sustainable intensification in West African drylands.
    Model validation through long-term promising sustainable maize/pigeon pea residue management in Malawi
    Mwale, C.D. ; Kabambe, V.H. ; Sakale, W.D. ; Giller, K.E. ; Kauwa, A.A. ; Ligowe, I. ; Kamalongo, D. - \ 2013
    In: Innovations as key to the Green Revolution in Africa - Vol. 1 / Bationo, A., Waswa, B., Okeyo, J.M., Maina, F., Kihara, J., Springer - ISBN 9789048125418 - p. 325 - 333.
    In the 2005/2006 season, the Model Validation Through Long-Term Promising Sustainable Maize/Pigeon Pea Residue Management experiment was in the 11th year at Chitedze and Chitala, and in the 8th year at Makoka and Zombwe. The experiment was a split-plot design with cropping system as the main plot and residue management as the subplot. All treatments were subjected to two fertilizer regimes. In the first regime, there was no addition of inorganic fertilizer and in the second, there was addition of inorganic fertilizer at area-specific fertilizer recommendation rate. The evaluation was done at Chitala, Chitedze, Makoka and Zombwe. Significant differences (P = 0.05) were observed in maize grain yield among sites and cropping systems. Highest grain yields were recorded at Chitedze (5,342 kg/ha). However, the response trend in grain yield to different cropping systems remained the same in all sites. Best yields were recorded in maize grown following pigeon pea in rotation system followed by maize intercropped with pigeon pea. The addition of inorganic fertilizer increased maize yield significantly. Removal or retention of crop residue in the field did not contribute any significant yield increase of maize across sites. For resource-poor smallholder farmers, growing maize/pigeon pea in rotation and maize intercropped with pigeon pea seems to be more profitable in terms of resource utilization and soil fertility improvements
    Tailoring conservation agriculture technologies to West Africa semi-arid zones: Building on traditional local practices for soil restoration
    Lahmar, R. ; Bationo, B.A. ; Lamso, N.D. ; Guéro, Y. ; Tittonell, P.A. - \ 2012
    Field Crops Research 132 (2012). - ISSN 0378-4290 - p. 158 - 167.
    senegal peanut basin - sub-saharan africa - native shrub communities - acid sandy soil - pearl-millet - fertility management - crop residue - piliostigma-reticulatum - guiera-senegalensis - carbon dynamics
    Low inherent fertility of tropical soils and degradation, nutrient deficiency and water stress are the key factors that hamper rainfed agriculture in semi-arid West Africa. Conservation Agriculture (CA) is currently promoted in the region as a technology to reduce soil degradation, mitigate the effect of droughts and increase crop productivity while reducing production costs. CA relies on the simultaneous use of three practices: (1) minimum or zero-tillage; (2) maintenance of a permanent soil cover and; (3) diversified profitable crop rotation. The most prominent aspect of CA for degraded lands in the semi-arid tropics would be the organic soil cover that impacts on the soil water balance, biological activity, soil organic matter build-up and fertility replenishment. Yet, the organic resources are the most limiting factor in Sahelian agroecosystems due to low biomass productivity and the multiple uses of crop residues, chiefly to feed the livestock. Hence, CA as such may hardly succeed in the current Sahelian context unless alternative sources of biomass are identified. Alternatively, we propose: (1) to gradually rehabilitate the biomass production function of the soil through increased nutrient input and traditional water harvesting measures that have been promoted as “soil and water conservation” technologies in the Sahel, e.g. zaï, in order to restore soil hydrological properties as prerequisite to boosting biomass production; (2) to encourage during this restorative phase the regeneration of native evergreen multipurpose woody shrubs (NEWS) traditionally and deliberately associated to crops and managed the year around and; (3) to shift to classical, less labour intensive CA practices once appropriate levels of soil fertility and water capture are enough to allow increased agroecosystem primary productivity (i.e., an active ‘aggradation’ phase followed by one of conservation). The CA systems we propose for the Sahelian context are based on intercropping cereal crops and NEWS building on traditional technologies practiced by local farmers. Traditionally, NEWS are allowed to grow in croplands during the dry season; they reduce wind erosion, trap organic residues and capture the Harmattan dust, influence the soil hydraulics and favour soil biological activity under their canopies. They are coppiced at the end of the dry season, leaves and twigs remain as mulch while branches are collected for domestic fuel and other uses. Shoots re-sprouting during the rainy season are suppressed as weeds. Such CA systems have limited competition with livestock due to the poor palatability of the shrub green biomass, which may increase their acceptance by smallholders. Such aggradation–conservation strategy is not free of challenges, as it may imply initial soil disturbance that entail important labour investments, substantially change the structure and management of the cropping system (annual crop-perennial plant), and lead to emerging tradeoffs in the use of resources at different scales. This paper offers a state of the art around NEWS and their integration in relay intercropping CA systems, discusses the above mentioned challenges and the main research needs to address them
    Simulation of potential yields of new rice varieties in the Senegal River Valley
    Vries, M.E. de; Sow, A. ; Bado, V.B. ; Sakane, N.S. - \ 2012
    In: Improving soil Fertility Recommendations in Africa using the Decision Support System for Agrotechnology Transfer (DSSAT) / Kihara, J., Fatondji, D., Jones, J.W., Hoogenboom, G., Tabo, R., Bationo, A., Dordrecht : Springer Science + Business Media - ISBN 9789400729599 - p. 141 - 155.
    Irrigated rice in the Sahel has a high yield potential, due to favorable climatic conditions. Simulation models are excellent tools to predict the potential yield of rice varieties under known climatic conditions. This study aimed to (1) evaluate new rice genotypes for the Sahel, and (2) calibrate simulation models to predict potential yield of irrigated rice in the Sahel. Two new inbred lines (ITA344 and IR32307) and one O. sativa × O. glaberrima line (WAS 161-B-9-2) were tested against IR64, an international check, and Sahel 108, locally the most popular rice cultivar. Field experiments were executed at two sites along the Senegal river, Ndiaye and Fanaye, differing in temperature regime and soil type. All cultivars were sown and transplanted at two sowing dates in February and March 2006. Observed grain yields varied from 7 to 10 t ha-1 and from 6 to 12 t ha-1 at Ndiaye and Fanaye, respectively. The number of days until maturity ranged from 119 to 158, depending on cultivar, sowing date and site. Experimental data of one sowing date was used to calibrate both the DSSAT and ORYZA2000 models. According to ORYZA2000, the same cultivars needed 400°Cd more in Fanaye than in Ndiaye to complete their cycle. ORYZA2000 simulated phenology well, but yield was underestimated. After calibrating DSSAT, different sets of genetic coefficients gave similar results. Genetic coefficients that reflected the observed phenology well resulted in lower than observed yields. Crop growth simulation is a powerful tool to predict yields, but local calibration at the same sowing date is needed to obtain useful results
    Effect of Farmer resource endowment and management strategies on spatial variability of soil fertility in contrasting agro-ecological zones in Zimbabwe
    Masvaya, E.N. ; Nyamangara, J. ; Nyawasha, R.W. ; Zingore, S. ; Delve, R.J. ; Giller, K.E. - \ 2011
    In: Innovations as key to the Green Revolution in Africa, Vol. 2 / Bationo, A., Waswa, B., Okeyo, J.M., Maina, F., Kihara, J., Springer - ISBN 9789048125418 - p. 1221 - 1229.
    Variability of soil fertility within and across farms poses a major challenge for increasing crop productivity in smallholder systems of sub-Saharan Africa (SSA). This study assessed the effect of farmers’ resource endowment and nutrient management strategies on variability in soil fertility and plant nutrient uptake between different fields in Gokwe South (average rainfall ~650 mm yr–1; 16.3 persons km–2) and Murewa (average rainfall ~850 mm yr–1; 44.1 persons km–2) districts, Zimbabwe. In Murewa, resource-endowed farmers applied manure (>3.5 t ha–1 yr–1) on fields closest to their homesteads (homefields) and none to fields further away (outfields). In Gokwe the manure was not targeted to any particular field, and farmers quickly abandoned outfields and opened up new fields further away from the homestead once fertility had declined, but homefields were continually cultivated. Soil-available phosphorus (P) was more concentrated in homefields (8–13 mg kg–1) of resource-endowed farmers than on outfields and all fields of poor resource farms (2–6 mg kg–1) in Murewa. Soil fertility decreased with increasing distance from the homestead in Murewa, while the reverse trend occurred in Gokwe South, indicating the impact of different soil fertility management strategies on spatial soil fertility gradients. In both districts, maize nutrient uptake showed deficiency in nitrogen (N) and P, implying that these were the most limiting nutrients. It was concluded that besides farmers’ access to resources, the direction of soil fertility gradients also depends on agro-ecological conditions, which influence resource management strategies.
    Targeting resources within diverse, heterogeneous and dynamic farming systems: Towards a ‘uniquely African green revolution’
    Tittonell, P.A. ; Vanlauwe, B. ; Misiko, M. ; Giller, K.E. - \ 2011
    In: Innovations as key to the Green Revolution in Africa - Vol. 1 / Bationo, A., Waswa, B., Okeyo, J.M., Maina, F., Kihara, J., Springer - ISBN 9789048125418 - p. 747 - 758.
    Smallholder farms in sub-Saharan Africa (SSA) are highly diverse and heterogeneous, often operating in complex socio-ecological environments. Much of the heterogeneity within the farming systems is caused by spatial soil variability, which results in its turn from the interaction between inherent soil/landscape variability and human agency through the history of management of different fields. Technologies and resources designed to improve crop productivity often generate weak responses in the poorest fields of smallholder farms. Thus, options for soil fertility improvement must be targeted strategically within heterogeneous farming systems to ensure their effectiveness and propensity to enhance the efficiency of resource (e.g. land, labour and nutrients) use at farm scale. Key issues in design of approaches for strategic targeting of resources include (1) inherent soil variability across agroecological gradients; (2) social diversity, farmers’ production orientations and livelihood strategies; (3) farmer-induced gradients of soil fertility, their causes and consequences of efficient allocation of scarce resources; (4) competing objectives and trade-offs that farmers face between immediate production goals and long-term sustainability and (5) the complexity of farmers’ own indicators of success. We used an analytical framework in which systems analysis is aided by survey, experiments and simulation modelling to analyse farming futures in the highlands of East Africa. Our work contributes to the development of ‘best-fit’ or tailor-made technologies, using combinations of mineral fertilizers and organic matter management from N2-fixing legumes and animal manures. Thus, we hope to contribute to the design of a ‘uniquely African green revolution’ called for by UN Director General Kofi Annan, which fits technology interventions to the diverse and heterogeneous smallholder farming systems of sub-Saharan Africa.
    Integrated Management of Fertilizers, Weed and Rice Genotypes Can Improve Rice Productivity
    Bado, B.V. ; Traore, B. ; Vries, M.E. de; Sow, A. ; Gaye, S. - \ 2011
    In: Innovations as Key to the Green Revolution in Africa / Bationo, A., Waswa, B., Okeyo, J.M., Maina, F., Kihara, J., Springer - ISBN 9789048125432 - p. 175 - 182.
    The influence of weed control on fertilizer nitrogen use efficiencies (NUEs) by rice genotypes was studied in the Senegal River valley of West Africa with a field experiment during four rice growing seasons. It was hypothesized that integrated management of technologies could improve rice productivity. The objective was to develop integrated high-return technologies that improve irrigated rice-based systems productivity and profitability. Data indicated that rice grain yields were affected by N fertilizer, genotypes and plant densities. In good weed control conditions, optimum doses of recommended N fertilizer varied from 80 to 180 kg N ha–1. Fertilizer N use efficiencies by genotypes were affected by weed control. Profitable management options of genotypes and N fertilizer recommendations have been identified. With a good control of weed, varieties and N fertilizer recommendations were suggested as integrated management options for farmers. But poor control of weed increased N lost, decreased grain yields and profitability. Two genotypes (WAS 55-B-B-2-1-2-5 and WAS 191-1-1-7 FKR) were found to be most competitive against weeds. However, no more than 60 kg N ha–1 should ever be recommended when weeds are poorly controlled. It was concluded that productivity and profitability of irrigated rice-based systems could be improved with integrated management options of genotypes, fertilizers and weed.
    Integrated soil fertility management: Operational definition and consequences for implementation and dissemination
    Vanlauwe, B. ; Bationo, A. ; Chianu, J. ; Giller, K.E. ; Merckx, R. ; Mokwunye, U. ; Ohiokpehai, O. ; Pypers, P. ; Tabo, R. ; Shepherd, K.D. ; Smaling, E.M.A. ; Woomer, P.L. ; Sanginga, N. - \ 2010
    Outlook on Agriculture 39 (2010)1. - ISSN 0030-7270 - p. 17 - 24.
    smallholder farms - western kenya - exploring diversity - resource-allocation - nutrient flows - variability - tropics - maize
    Traditional farming systems in Sub-Saharan Africa depend primarily on mining soil nutrients. The African green revolution aims to intensify agriculture through the dissemination of integrated soil fertility management (ISFM). This paper develops a robust and operational definition of ISFM based on detailed knowledge of African farming systems and their inherent variability and of the optimal use of nutrients. The authors define ISFM as a set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs and improved germplasm, combined with the knowledge on how to adapt these practices to local conditions, aimed at maximizing agronomic use efficiency of the applied nutrients and improving crop productivity. All inputs need to be managed in accordance with sound agronomic principles. The integration of ISFM practices into farming systems is illustrated with the dual-purpose grain legume-maize rotations in the savannas and fertilizer micro-dosing in the Sahel. Finally, the dissemination of ISFM practices is discussed
    Nutrient balances for different farm types in Southern Mali
    Kanté, S. ; Smaling, E.M.A. ; Keulen, H. van - \ 2008
    In: Advances in Integrated Soil Fertility Management in Sub-Saharan Africa: Challenges and Opportunities / Bationo, A., Dordrecht : Springer - ISBN 9781402057595 - p. 557 - 566.
    Soil science, population growth and food production: some historical developments
    Hartemink, A.E. - \ 2007
    In: Advances in integrated Soil Fertility Management in sub-Saharan Africa: Challenges and Opportunities / Bationo, A., Berlin-Heidelberg : Springer - ISBN 9781402057595 - p. 85 - 97.
    The world¿s population has doubled since 1960. Currently, the developing world accounts for about 95% of the population growth with Africa as the world¿s fastest growing continent. The growing population has many implications but most of all it requires an increase in agricultural production to meet food demand. Soil science has a long tradition of considering the growth in food production in relation to the increasing human population. This paper reviews some of the major developments in these subjects from a soil scientist¿s perspective. It starts with the work of Thomas Malthus and various subsequent studies relating population growth and food production. Population growth and projections up to the year 2050 are discussed. The main soil studies since the 1920s are reviewed with a focus on those conducted in the Dutch East Indies and the UK. The productivity of soil science measured by the number of publications and soil scientists has kept pace with the increasing population. Although the number of undernourished people in the world is on the decline, it is concluded that continued efforts from soil scientists remains needed particularly now the focus of attention in the USA and Western Europe moves from population growth per se to population ageing and obesity.
    Nutrient dynamics on smallholder farms in Teghane, Northern Highlands of Ethiopia
    Abegaz Yimer, A. ; Keulen, H. van; Haile, M. ; Oosting, S.J. - \ 2007
    In: Advances in Integrated Soil Fertility Management in Sub-Saharan Africa: Challenges and Opportunities / Bationo, A., Springer - ISBN 9781402057595 - p. 365 - 378.
    African soils: their productivity and profitability of fertilizer use : background paper for the African Fertilizer Summit 9-13th June 2006, Abuja, Nigeria
    Bationo, A. ; Hartemink, A.E. ; Lungo, O. ; Naimi, M. ; Okoth, P. ; Smaling, E.M.A. ; Thiombiano, L. - \ 2006
    Togo : IFDC (Background papers )
    bodemvruchtbaarheid - afrika - kunstmeststoffen - landdegradatie - soil fertility - africa - fertilizers - land degradation
    Partial balance of nitrogen in a maize cropping system in humic nitisol of Central Kenya
    Kimetu, J.M. ; Mugendi, D.N. ; Bationo, A. ; Palm, C.A. ; Mutuo, P.K. ; Kihara, J. ; Nandwa, S. ; Giller, K.E. - \ 2006
    Nutrient Cycling in Agroecosystems 76 (2006)2-3. - ISSN 1385-1314 - p. 261 - 270.
    green manure - volatilization losses - subhumid highlands - semiarid tropics - fertilizers - recovery - mineralization - agroforestry - management - leucaena
    The application of nitrogen in a soil under agricultural production is subject to several pathways including de-nitrification, leaching and recovery by an annual crop. This is as well greatly influenced by the management practices, nitrogen source and soil conditions. The main objective of this study was to investigate the loss of nitrogen (N) through nitrous oxide (N2O) emissions and mineral N leaching and uptake by annual crop as influenced by the N source. The study was carried out at Kabete in Central Kenya. Measurements were taken during the second season after two seasons of repeated application of N as urea and Tithonia diversifolia (tithonia) leaves. Results obtained indicated that nitrous oxide (N2O) emissions at 4 weeks after planting were as high as 12.3 -g N m -2 h-1 for tithonia treatment and 2.9 -g N m-2 h-1 for urea treatment. Tithonia green biomass treatment was found to emit N2O at relatively higher rate compared to urea treatment. This was only evident during the fourth week after treatment application.Soil mineral N content at the end of the season increased down the profile. This was evident in the three treatments (urea, tithonia and control) investigated in the study. Urea treatment exhibited significantly higher mineral N content down the soil profile (9% of the applied N) compared to tithonia (0.6% of the applied N). This was attributed to the washing down of the nitrate-N from the topsoil accumulating in the lower layers of the soil profile. However, there was no significant difference in N content down the soil profile between tithonia treatment and the control. It could be concluded that there was no nitrate leaching in the tithonia treatment. Nitrogen recovery by the maize crop was higher in the urea treatment (76% of the applied N) as compared to tithonia treatment (55.5% of the applied N). This was also true for the residual mineral N in the soil at the end of the season which was about 7.8% of the applied N in the urea treatment and 5.2% in the tithonia treatment.From this study, it was therefore evident that although there is relatively lower N recovery by maize supplied with tithonia green biomass compared to maize supplied with urea, more nitrogen is being lost (through leaching) from the soil¿plant system in the urea applied plots than in tithonia applied plots. However, a greater percentage (37.8%) of the tithonia-applied N could not be accounted for and might have been entrapped in the soil organic matter unlike urea-applied N whose greater percentage (92%) could be accounted for.
    Soil fertility research in tropical and temperate regions - achievements and differences
    Hartemink, A.E. - \ 2004
    In: Improving human welfare and environmental conservation by empowering farmers to combat soil fertility degradation, Yaoundé, Cameroon, May 17-21, 2004 / Bationo, A., Kimetu, J., Kihara, J., Nairobi : TSBF - p. 6 - 7.
    Agro-ecological characterization as a tool for sustainable use of inland valley
    Windmeijer, P.N. ; Duivenbooden, N. van - \ 1996
    In: Gestion durable des sols et environnement en Afrique intertropicale / Thiombiano, L., de Blic, P., Bationo, A., - p. 29 - 40.
    Inland valleys cover some 22-52 million hectares in West Africa. In spite of their agricultural potential, they are used marginally. The large physical and biotic complexity and heterogeneity of inland valleys explain why little progress has been madein their systematic characterization. Building on a method for multi-scale agro-ecological characterization, this paper proposes a method for characterization at semi-detailed level (scales between 1 : 25 000 and 1 : 50 000), and provides examples and interpretations for two sites in different agro-ecological zones in Ivory Coast.
    Nutrient stocks and flows in West African soils
    Rhodes, E. ; Bationo, A. ; Smaling, E.M.A. ; Visker, C. - \ 1996
    In: Restoring and maintaining the productivity of West African soils: key to sustainable development / Mokwunye, A.U., de Jager, A., Smaling, E.M.A., - p. 22 - 32.
    A literature review is given of nutrient stocks and flows in West Africa. The issue is addressed on different spatial scales, viz. agro-ecological zones, catchment areas and farms, fields and niches. Only few areas have positive nutrient balances, mainly as a result of site-specific farm management. Most areas have both low nutrient stocks and negative nutrient balances, painting a gloomy future for crop and livestock production.
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