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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    Understanding Landscape Multifunctionality in a Post-forest Frontier: Supply and Demand of Ecosystem Services in Eastern Amazonia
    Pinillos, Daniel ; Bianchi, Felix J.J.A. ; Poccard-Chapuis, Rene ; Corbeels, Marc ; Tittonell, Pablo ; Schulte, Rogier P.O. - \ 2020
    Frontiers in Environmental Science 7 (2020). - ISSN 2296-665X
    ecosystem services - land use - land-use pathways - landscape multi-functionality - pedo-morphology - policy targets

    Sustainable food production requires approaches that reconcile agricultural production with the conservation and sustainable use of natural resources, biodiversity and associated ecosystem services. While the contribution of agriculture to the provision of individual ecosystem services has received considerable scientific attention, little is known about the extent to which tropical landscapes can meet societal expectations related to food production and environmental sustainability simultaneously. We assessed how the spatial configuration of pedo-morphology and land uses influences the provision of three soil-based ecosystem services in eastern Amazonia: carbon storage (CS), habitat for biodiversity (HB), and agricultural commodity production (CP). We use the Functional Land Management framework to assess the supply and demand of these ecosystem services in a spatially explicit manner to identify areas of (mis)matches and trade-offs in the municipality of Paragominas, Brazil. The supply of ecosystem services was informed by a literature review for the various combinations of pedo-morphological characteristics and land uses in the region. The demand for ecosystem services was mapped based on federal and state policy targets. Mapping the supply and demand of CS indicated that half of the carbon in the region is stored in remnants of undisturbed forest which cover only a third of the municipality. Demand for HB in terms of forested area is met but it does not guarantee safeguarding biodiversity. Roughly a third of the territory shows scarce quality of HB even when compliant with legislation. Concerning CP, we identified areas where both supply and the demand to increase production are relative high due to road access and lower intensification costs. The demand for agricultural production can eventually incentivize the expansion of agriculture on fertile soils, which could compromise environmental targets. Our results suggest that the simultaneous delivery of multiple ecosystem services may require land-use pathways that combine land sparing and sharing approaches. Our analysis can inform integrated land-use planning initiatives where, historically, the supply and demand for CP have been the single dominant driver for the current landscape configuration.

    Does Size Matter? A Critical Assessment of Meta-Analyses in Contested Agronomy
    Krupnik, Timothy J. ; Andersson, J.A. ; Rusinamhodzi,, L. ; Corbeels, M. ; Shennan, C. ; Gerard, B. - \ 2019
    Experimental Agriculture 55 (2019)2. - ISSN 0014-4797 - p. 200 - 229.
    Intended to test broad hypotheses and arrive at unifying conclusions, meta-analysis is the process of extracting, assembling, and analyzing large quantities of data from multiple publications to increase statistical power and uncover explanatory patterns. This paper describes the ways in which meta-analysis has been applied to support claims and counter-claims regarding two topics widely debated in agricultural research, namely organic agriculture (OA) and conservation agriculture (CA). We describe the origins of debate for each topic and assess prominent meta-analyses considering data-selection criteria, research question framing, and the interpretation and extrapolation of meta-analytical results. Meta-analyses of OA and CA are also examined in the context of the political economy of development-oriented agricultural research. Does size matter? We suggest that it does, although somewhat ironically. While meta-analysis aims to pool all relevant studies and generate comprehensive databases from which broad insights can be drawn, our case studies suggest that the organization of many meta-analyses may affect the generalizability and usefulness of research results. The politicized nature of debates over OA and CA also appear to affect the divergent ways in which meta-analytical results may be interpreted and extrapolated in struggles over the legitimacy of both practices. Rather than resolving scientific contestation, these factors appear to contribute to the ongoing debate. Meta-analysis is nonetheless becoming increasingly popular with agricultural researchers attracted by the power for the statistical inference offered by large datasets. This paper consequently offers three suggestions for how scientists and readers of scientific literature can more carefully evaluate meta-analyses. First, the ways in which papers and data are collected should be critically assessed. Second, the justification of research questions, framing of farming systems, and the scales at which research results are extrapolated and discussed should be carefully evaluated. Third, when applied to strongly politicized topics situated in an arena of scientific debate, as is the case with OA and CA, more conservative interpretations of meta-analytical results that recognize the socially and politically embedded nature of agricultural research is are needed.
    The science base of a strategic research agenda - Executive Summary
    Bray, A.W. ; Kim, J.H. ; Schrumpf, M. ; Peacock, C. ; Banwart, S. ; Schipper, L. ; Angers, D. ; Chirinda, N. ; Lopes Zinn, Y. ; Albrecht, A. ; Kuikman, P.J. ; Jouquet, P. ; Demenois, J. ; Farrell, M. ; Fontaine, S. ; Soussana, J.F. ; Kuhnert, M. ; Milne, E. ; Taghizadeh-Toosi, A. ; Cerri, C.E.P. ; Corbeels, M. ; Cardinael, R. ; Alcántara Cervantes, V. ; Olesen, J.E. ; Batjes, N.H. ; Heuvelink, G.B.M. ; Maia, S.M.F. ; Keesstra, S.D. ; Claessens, L.F.G. ; Madari, B.E. ; Verchot, L. ; Nie, W. - \ 2019
    EU - 16 p.
    A summary presenting the challenges for soil carbon sequestration research, hypotheis to be further tested and key research (and innvation) products.
    Grazing management for more resilient mixed livestock farming systems on native grasslands of southern South America
    Modernel, Pablo ; Picasso, Valentin ; Carmo, Martin Do; Rossing, Walter A.H. ; Corbeels, Marc ; Soca, Pablo ; Dogliotti, Santiago ; Tittonell, Pablo - \ 2019
    Grass and Forage Science 74 (2019)4. - ISSN 0142-5242 - p. 636 - 649.
    drought - grazing management - livestock farming systems - native grasslands - resilience - Rio de la Plata grasslands

    Droughts in southern South America affect grazing systems in many ways. They reduce biomass productivity; decrease livestock feed intake, weight and reproductive performance; increase farmers’ costs; and reduce farm income. It was hypothesized that simple grazing management variables affect the resilience of grazing systems to droughts at the paddock and farm scales. The effects of grazing management on herbage and animal production were assessed at paddock level, and how technological and structural variables relate to the production and economic performances at farm level. Results of a grazing experiment controlling herbage allowance at paddock level showed that resistance of herbage accumulation and animal live weight to drought was significantly higher for paddocks with higher pre-drought herbage allowance than for those managed to low herbage allowance treatments. A strong positive linear relationship was found between pre-drought herbage height and resistance of herbage accumulation rate (p <.01). In a longitudinal study of nine farms in Uruguay, resistance of cow pregnancy rate to drought was positively correlated with cow pregnancy rate (r =.72, p =.02) and farm net income (r =.78, p =.02), and negatively correlated with sheep-to-cattle ratio (r = −.80, p =.01). These correlations suggest that farms with higher incomes and low proportions of sheep in the herd withstand drought better (in terms of pregnancy rate). Four common regional production strategies were identified that react differently when farmers face drought, and these results can aid farmers in those regions to design more resilient mixed livestock farming systems and can inform policymakers about effective strategies for mitigating drought impacts in the region.

    Livestock farming systems on South American native grasslands: when production meets conservation
    Modernel, Pablo - \ 2018
    Wageningen University. Promotor(en): P.A. Tittonell, co-promotor(en): M. Corbeels; W.A.H. Rossing; S. Dogliotti Moro. - Wageningen : Wageningen University - ISBN 9789463435291 - 237

    The livestock industry faces the double challenge of coping with the increasing demand for animal protein and reducing its high load on the environment. On the one hand, livestock has been recognized for its contribution to the economy, providing 40% of global agricultural GDP, ensuring a living for farmers, maintaining rural heritage and traditional farming landscapes, providing draft power, fuel, and sources of nutrients, particularly proteins. On the other hand, the livestock industry emits 13-18% of global greenhouse gas emissions, occupies 33% of total arable land and is responsible for 8% of global water use.

    South American Río de la Plata grasslands comprise more than 500,000 km2, including all of Uruguay, north-eastern Argentina and southern Brazil. These grasslands provide feed for 43 million heads of cattle and 14 million sheep. The biome is habitat of 4000 native plant species, 300 species of birds, 29 species of mammals, 49 species of reptiles and 35 species of amphibians. They store 5% of the total soil organic carbon stock of Latin America on 3% of the area, and they protect soils from erosion. Cropping areas and livestock herds have shifted spatially. Regions that used to integrate crop-livestock systems have specialized in cropping, decreasing stocks but increasing beef confined systems (feedlots). Regions with historical predominance of cattle due to low-potential productive have been increasing in stocking rates which could aggravate overgrazing problems. Land-use change very likely increased provisioning services while very likely decreased supporting and regulating services. Overgrazing regimes with low forage allowances were predominantly associated with negative effects on provisioning and supporting and regulating ecosystem services. The most documented impacts of land use-change and overgrazing include: reducing soil organic carbon stocks and the diversity of plants, birds and mammals, and increasing soil erosion.

    In order to identify the diversity in farming systems, the first biome-wide beef farm typology of the Rio de la Plata grasslands was constructed. While seven farm types were identified, most of the farms belonged to the family farms, with cow-calf operations using native grasslands. We identified positive deviant farms, which performed excellently in economic and environmental terms when compared to the other farms in the region, and, more generally, to farms from OECD countries. These positive deviant farmers achieved 192 kg LW ha-1 yr-1 or 201 US$ ha-1 year-1 with negligible fossil energy consumption and phosphorus surplus, low carbon footprint (13 kg CO2 eq kg LW-1) and having over 95% of their land under native grassland. This means that the native grassland-based farming systems of the Río de la Plata grasslands region have the potential to produce high-quality beef with low use of inputs and preserve biodiversity, thus constituting one of the most sustainable livestock farming system models. However, the greenhouse gas emissions per unit of product may be high when compared to other forms of protein production as a consequence of the digestive system of the ruminant.

    Droughts may affect grazing systems at multiple levels: they reduce plant growth and biomass production, decrease intake, weight, and reproductive performance of livestock, increase costs and reduce income for farmers, and affect rural communities and even countries’ economies. The relationship between management and resilience to drought at paddock and farm level was studied. At paddock level, higher herbage allowance increased the resistance of herbage accumulation rate and animal weight. A positive relationship was found between pre-drought herbage height and resistance of herbage accumulation to drought, which means that herbage height can be used as a guideline for grassland management. The sheep to cow ratio was negatively correlated with pregnancy rate of cows, a key variable defining meat production and farm income.

    The economic and environmental issues with livestock production systems discussed above demand local actions by stakeholders. One such action is to actively work on the redesign of individual farms, to improve farmer livelihoods and ecosystem service provision. To aid this process we present and evaluate a dynamic whole-farm simulation model (PASpALuM). The model elucidates the relations between grazing management, productivity and environmental impact. The herbage dynamics module was evaluated against experimental data, showing acceptable simulation of the seasonal dynamics of herbage height and mass. A simulation exercise explored the effect of grazing management on enteric methane emissions and soil organic carbon from 2007 to 2009.

    Maintaining this example of nature inclusive agriculture and improving it to the level of agriculture-inclusive nature, seems possible by changing grassland management strategies. Contributions to greenhouse gas emissions by livestock will remain, but this should be seen as the price to be paid for maintaining a unique and priceless biome that cannot be maintained in another way than through low-intensity grazing by ruminants. The contribution of greenhouse gas emissions from livestock systems on native grasslands is determined by the carrying capacity of the grasslands and will remain much lower per hectare than that of intensive pastures. Solutions for global meat production should be considered within social and ecological boundaries. Such quest is not advanced by unilateral reliance on one size fits all efficiency measures.

    Identification of beef production farms in the Pampas and Campos area that stand out in economic and environmental performance
    Modernel, P. ; Dogliotti, S. ; Alvarez, S. ; Corbeels, M. ; Picasso, V. ; Tittonell, P. ; Rossing, W.A.H. - \ 2018
    Ecological Indicators 89 (2018). - ISSN 1470-160X - p. 755 - 770.
    Carbon footprint - Grazing - Livestock - Multivariate analysis - Nutrient balance - South America - Sustainability
    Worldwide, native grasslands are being converted to non-native pastures and cropland. This process threatens local grassland biomes as well as the livelihoods of farm families that utilize these grasslands. In the Río de la Plata grasslands region meat production and multispecies native grasslands have coexisted for more than 400 years. Low levels of meat productivity and farm income, however, trigger replacement of native grasslands by crops and leys and threaten the survival of local beef farming systems. We studied the economic and environmental performance of beef farming in the region based on interviews and field measurements on 280 case study farms with the following aims: (a) to identify the multi-functional economic and environmental performance of beef farms across the Rio de la Plata grasslands biome; (b) to identify farms with ‘outstanding’ multi-functional performance; (c) to compare performance levels with those found in other regions; and (d) to discuss the implications of the outstanding farms for the development of new systems of meat production. The representativeness of the case study farms was ascertained by comparing them with a farm typology constructed from survey data of 15,448 beef farms situated predominantly on native grasslands in Argentina, Brazil and Uruguay. We identified seven farm types on the basis of farm size, labour, farm specialization, land use and stocking rate. We identified positive deviant farms based on Pareto-ranking and compared these with a classification based on threshold values provided by experts. Out of the 280 farms, 41 were ranked as Pareto-optimal, i.e. outperformed other farms in one or more indicators without being outperformed in other indicators. Out of these, 5 were positive deviants, achieving on average 192 kg LW ha−1 yr−1 of livestock productivity and 201 US$ ha−1 year−1 farm income, having most favourable values for fossil energy consumption, phosphorus balance, carbon footprint and having over 95% of their land under native grassland as a proxy for biodiversity conservation value. Four of these farms belonged to farm types that together represented 55% of the population, suggesting scope for widescale improvement. Compared to the values reported for the OECD countries the beef farming systems of the Río de la Plata grasslands region consume less energy and positive deviant farms demonstrated approximately average livestock productivity and carbon footprint. Increasing livestock productivity in the Rio de la Plata grasslands region resulted in a stronger decline of the carbon footprint without compromising the current negligible levels of fossil fuel energy use. Further elucidation of management practices that lead to positive deviant performance will require modelling of the interaction of pasture and herd dynamics at farm level and is needed to support targeted policy support for sustainable natural grassland-based beef production in the region.
    Modelling cereal crops to assess future climate risk for family food self-sufficiency in southern Mali
    Traore, Bouba ; Descheemaeker, Katrien ; Wijk, Mark T. van; Corbeels, Marc ; Supit, Iwan ; Giller, Ken E. - \ 2017
    Field Crops Research 201 (2017). - ISSN 0378-4290 - p. 133 - 145.
    APSIM - Climate change - Crop simulation modelling - Fertilizer use - Planting date - Sub-Saharan Africa

    Future climate change will have far reaching consequences for smallholder farmers in sub-Saharan Africa, the majority of whom depend on agriculture for their livelihoods. Here we assessed the farm-level impact of climate change on family food self-sufficiency and evaluated potential adaptation options of crop management. Using three years of experimental data on maize and millet from an area in southern Mali representing the Sudano-Sahelian zone of West Africa we calibrated and tested the Agricultural Production Systems sIMulator (APSIM) model. Changes in future rainfall, maximum and minimum temperature and their simulated effects on maize and millet yield were analysed for climate change predictions of five Global Circulation Models (GCMs) for the 4.5 Wm−2 and 8.5 Wm−2 radiative forcing scenario (rcp4.5 and rcp8.5). In southern Mali, annual maximum and minimum temperatures will increase by 2.9 °C and 3.3 °C by the mid-century (2040–2069) as compared with the baseline (1980–2009) under the rcp4.5 and rcp8.5 scenario respectively. Predicted changes in the total seasonal rainfall differed between the GCMs, but on average, seasonal rainfall was predicted not to change. By mid-century maize grain yields were predicted to decrease by 51% and 57% under current farmer's fertilizer practices in the rcp4.5 and rcp8.5 scenarios respectively. APSIM model predictions indicated that the use of mineral fertilizer at recommended rates cannot fully offset the impact of climate change but can buffer the losses in maize yield up to 46% and 51% of the baseline yield. Millet yield losses were predicted to be less severe under current farmer's fertilizer practices by mid-century i.e. 7% and 12% in the rcp4.5 and rcp8.5 scenario respectively. Use of mineral fertilizer on millet can offset the predicted yield losses resulting in yield increases under both emission scenarios. Under future climate and current cropping practices, food availability is expected to reduce for all farm types in southern Mali. However, large and medium-sized farms can still achieve food self–sufficiency if early planting and recommended rates of fertilizer are applied. Small farms, which are already food insecure, will experience a further decrease in food self-sufficiency, with adaptive measures of early planting and fertilizer use unable to help them achieve food self-sufficiency. By taking into account the diversity in farm households that is typical for the region, we illustrated that crop management strategies must be tailored to the capacity and resource endowment of local farmers. Our place-based findings can support decision making by extension and development agents and policy makers in the Sudano-Sahelian zone of West Africa.

    Economic assessment of conservation agriculture options in mixed crop-livestock systems in Brazil using farm modelling
    Alary, V. ; Corbeels, M. ; Affholder, F. ; Alvarez, S. ; Soria, A. ; Valadares Xavier, J.H. ; Silva, F.A.M. Da; Scopel, E. - \ 2016
    Agricultural Systems 144 (2016). - ISSN 0308-521X - p. 33 - 45.
    Direct seeding mulch-based cropping (DMC) systems are often considered as an efficient way of combining ecological sustainability and economic viability while maintaining or increasing agricultural productivity. This paper describes a modelling analysis of the functioning of family farms in rural settlements of the agrarian reform in the Cerrados of Brazil. The aim was to assess the impact of the introduction of DMC systems with and without cover crops on crop-livestock management and net household income. A bio-economic farm model based on optimization of a utility function under multiple constraints was developed, capturing the interactions between livestock activities and the introduction of DMC systems. The model was run for six farms representing three farm types in the study area: 1) subsistence-oriented mixed crop-livestock farms; 2) market-oriented dairy farms; and 3) mixed crop-livestock farms, oriented to meat marketing. The following maize-based DMC systems were evaluated: a DMC system with mulch from residues of the previous maize crop and no cover crop, and two DMC systems with a fodder species, Brachiaria brizanta or Cajanus cajan, as cover crop. The simulated adoptability of DMC systems by farmers of the assentamentos depended to a large extent on the yields and feed quality of the fodder species. The modelling results suggested that DMC with C. cajan as cover crop was the best suitable option for all simulated farm types. This was mainly explained by its high feed value (expressed in crude protein content). Furthermore, in the process of intensification and specialization in dairy production, farmers were likely to shift from using maize for pig husbandry to feeding it to the dairy cows. The introduction of cover crops in the farm systems was a source of additional animal feed during the dry season that was cheaper than the purchase of feed concentrates, when the size of the dairy herd did not exceed a certain threshold.
    Land Use Change and Intensification, and Family Farmers in Uruguay : The Crop/Cattle Dilemma
    Modernel Hristoff, P.D. ; Dogliotti, Santiago ; Picasso, V. ; Rossing, W.A.H. ; Corbeels, Marc ; Tittonell, P.A. - \ 2016
    Land use change and ecosystem service provision in Pampas and Campos grasslands of southern South America
    Modernel Hristoff, Pablo ; Rossing, W.A.H. ; Corbeels, M. ; Dogliotti, S. ; Picasso, V. ; Tittonell, P. - \ 2016
    Environmental Research Letters 11 (2016)11. - ISSN 1748-9326 - 21 p.
    New livestock production models need to simultaneously meet the increasing global demand for meat and preserve biodiversity and ecosystem services. Since the 16th century beef cattle has been produced on the Pampas and Campos native grasslands in southern South America, with only small amounts of external inputs. We synthesised 242 references from peer-reviewed and grey literature published between 1945 and mid-2015 and analysed secondary data to examine the evidence on the ecosystem services provided by this grassland biodiversity hotspot and the way they are affected by land use changes and their drivers. The analysis followed the requirements of systematic review from the PRISMA statement (Moher et al 2009 Acad. Clin. Ann. Intern. Med. 151 264–9). The Pampas and Campos provide feed for 43 million heads of cattle and 14 million sheep. The biome is habitat of 4000 native plant species, 300 species of birds, 29 species of mammals, 49 species of reptiles and 35 species of amphibians. The soils of the region stock 5% of the soil organic carbon of Latin America on 3% of its area. Driven by high prices of soybean, the soybean area increased by 210% between 2000 and 2010, at the expense of 2 million ha (5%) of native grassland, mostly in the Pampas. Intensification of livestock production was apparent in two spatially distinct forms. In subregions where cropping increased, intensification of livestock production was reflected in an increased use of grains for feed as part of feedlots. In subregions dominated by native grasslands, stocking rates increased. The review showed that land use change and grazing regimes with low forage allowances were predominantly associated with negative effects on ecosystem service provision by reducing soil organic carbon stocks and the diversity of plants, birds and mammals, and by increasing soil erosion. We found little quantitative information on changes in the ecosystem services water provision, nutrient cycling and erosion control. We discuss how changing grazing regimes to higher forage allowance can contribute to greater meat production and enhancing ecosystem services from native grasslands. This would require working with farmers on changing their management strategies and creating enabling economic conditions.
    Use of crop modelling to assess climate risk management for family food self-sufficiency in southern Mali
    Traore, B. ; Descheemaeker, K.K.E. ; Wijk, M.T. van; Corbeels, Marc ; Supit, I. ; Giller, K.E. - \ 2016
    - p. 412 - 413.
    Diversity in crop residue management across an intensification gradient in southern Africa : System dynamics and crop productivity
    Rusinamhodzi, Leonard ; Corbeels, Marc ; Giller, Ken E. - \ 2016
    Field Crops Research 185 (2016). - ISSN 0378-4290 - p. 79 - 88.
    Crop-livestock systems - Extensification - Farm diversity - Maize production - Smallholder farms

    Crop residues are important for livestock feed and nutrient cycling among many other functions on smallholder farming systems of sub-Saharan Africa. The objective of this study was to assess differences in resource endowment, crop productivity and crop residue management in selected sites in southern Africa. Three sites were selected along a gradient of intensification of crop production; Murehwa, Zimbabwe and Ruaca and Gorongosa, central Mozambique. Murehwa and Ruaca have mixed crop-livestock systems with more intensive crop production in Murehwa. Gorongosa is predominantly crop based with small livestock that do not impact on crop production. A combination of land size and cattle ownership was the major attribute that defined wealth status among farmers in mixed crop-livestock systems whereas land size and labor availability were important under crop-based extensification systems. Farm systems were more diverse where livestock was more important. The wealthiest farmers (resource group-RG1) in Murehwa produced an average of 2.2 t ha-1 maize crop residues, and productivity decreased with decrease in resource ownership with the poorest (RG4) achieving only 0.8 t ha-1. In Ruaca 1.3 and 0.5 t ha-1 was produced by RG1 and RG4 respectively, whereas in Gorongosa 0.4 and 0.2 t ha-1 was produced by RG1 and RG4. These crop residues are insufficient to achieve the minimum threshold of soil cover (30%) required for the practice of conservation agriculture. However, they can provide sufficient feed to sustain livestock of RG1 farmers in Murehwa for 63 days and 54 days for RG2 farmers. In Ruaca, they can feed cattle for 37 days for RG1 and 17 days for RG2 farmers. The product of livestock × population density determined the extent and manner in which crop residues are used. The population density limited the extent of the grazing area, increased grazing frequency and reduced the grazing quality leading to the need to supplement animal feed with crop residues. Farmers preferentially allocate crop residues to livestock where labor is available. The crop residues fed to animals allow farmers to increase manure quantity and quality which explains the major differences in crop productivity between the different resource groups. In the absence of cattle, crop residues are burned before the cropping season to facilitate land clearance. In conclusion, land size, cattle ownership and labor availability largely define the intensity of crop production and the fate of crop residues on smallholder farms in southern Africa.

    Soil variability and crop yield gaps in two village landscapes of Burkina Faso
    Diarisso, Tidiane ; Corbeels, Marc ; Andrieu, Nadine ; Djamen, Patrice ; Douzet, Jean Marie ; Tittonell, Pablo - \ 2016
    Nutrient Cycling in Agroecosystems 105 (2016)3. - ISSN 1385-1314 - p. 199 - 216.
    Farm typology - Nutrient balances - Resource use efficiency - Soil fertility gradients - West Africa

    Low crop yields in the savannah zones of West Africa are commonly attributed to rainfall deficits and poor soil fertility. In this study, an assessment was made on how the position of fields belonging to different farm types can explain soil variability and related crop yield gaps in two villages in Burkina Faso, Yilou and Koumbia, located, respectively, in the Sudano-Sahelian and Sudanian agro-ecological zones. In each village, four farm types were identified. Soil fertility was generally poor and use of nutrient inputs low in most of the farmer’s fields . As a consequence, yields for most crops were low, but differences among farm types were found, which can be linked to their socioeconomic characteristics that influence the amount of inputs used. Application of fertilizers differed also between fields within farms and tended to be greater on the fields near the homesteads in the village of Yilou, especially for organic fertilizers. At both villages, the rates of N and K inputs were insufficient to compensate for their respective output rates, leading to negative partial nutrient balances . The existence of patchworks of soil fertility gives rise to a wide variation in crop responses to fertilizers. Exploitable yield gaps were substantial and to a large extent related to the low fertility status of soils and sub-optimal fertilizer applications.

    Beyond conservation agriculture
    Giller, K.E. ; Andersson, J.A. ; Corbeels, Marc ; Kirkegaard, John ; Mortensen, David ; Erenstein, Olaf ; Vanlauwe, Bernard - \ 2015
    Frontiers in Plant Science 6 (2015)OCTOBER. - ISSN 1664-462X - 14 p.
    Climate smart agriculture - Legumes - Mulch - Soil erosion - Sustainable intensification - Systems agronomy

    Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption of CA, particularly on large farms in the Americas and Australia, where farmers harness the tools of modern science: highly-sophisticated machines, potent agrochemicals, and biotechnology. Over the past 10 years CA has been promoted among smallholder farmers in the (sub-) tropics, often with disappointing results. Growing evidence challenges the claims that CA increases crop yields and builds-up soil carbon although increased stability of crop yields in dry climates is evident. Our analyses suggest pragmatic adoption on larger mechanized farms, and limited uptake of CA by smallholder farmers in developing countries. We propose a rigorous, context-sensitive approach based on Systems Agronomy to analyze and explore sustainable intensification options, including the potential of CA. There is an urgent need to move beyond dogma and prescriptive approaches to provide soil and crop management options for farmers to enable the Sustainable Intensification of agriculture.

    Ecological intensification in Río de la Plata grasslands
    Modernel Hristoff, P.D. ; Rossing, W.A.H. ; Dogliotti, Santiago ; Corbeels, Marc ; Picasso, V. ; Tittonell, P.A. - \ 2015
    A statistical analysis of three ensembles of crop model responses to temperature and CO2 concentration
    Makowski, D. ; Asseng, S. ; Ewert, F. ; Bassu, S. ; Durand, J.L. ; Li, G. ; Martre, P. ; Adam, M.Y.O. ; Aggarwal, P.K. ; Angulo, C. ; Baron, C. ; Basso, B. ; Bertuzzi, P. ; Biernath, C. ; Boogaard, H.L. ; Boote, K.J. ; Bouman, B. ; Bregaglio, S. ; Brisson, N. ; Buis, S. ; Cammarano, D. ; Challinor, A.J. ; Confalonieri, R. ; Conijn, J.G. ; Corbeels, M. ; Deryng, D. ; Sanctis, G. De; Doltra, J. ; Fumoto, T. ; Gayler, S. ; Gaydon, D. ; Goldberg, R. ; Grant, R.F. ; Grassini, P. ; Hatfield, J.L. ; Hasegawa, T. ; Heng, L. ; Hoek, S.B. ; Hooker, J. ; Hunt, L.A. ; Ingwersen, J. ; Izaurralde, C. ; Jongschaap, R.E.E. ; Jones, J.W. ; Kemanian, R.A. ; Kersebaum, K.C. ; Kim, S.H. ; Lizaso, J. ; Marcaida III, M. ; Müller, C. ; Nakagawa, H. ; Naresh Kumar, S. ; Nendel, C. ; O'Leary, G.J. ; Olesen, J.E. ; Oriol, P. ; Osborne, T.M. ; Palosuo, T. ; Pravia, M.V. ; Priesack, E. ; Ripoche, D. ; Rosenzweig, C. ; Ruane, A.C. ; Ruget, F. ; Sau, F. ; Semenov, M.A. ; Shcherbak, I. ; Singh, B. ; Soo, A.K. ; Steduto, P. ; Stöckle, C.O. ; Stratonovitch, P. ; Streck, T. ; Supit, I. ; Tang, L. ; Tao, F. ; Teixeira, E. ; Thorburn, P. ; Timlin, D. ; Travasso, M. ; Rötter, R.P. ; Waha, K. ; Wallach, D. ; White, J.W. ; Wilkens, P. ; Williams, J.R. ; Wolf, J. ; Ying, X. ; Yoshida, H. ; Zhang, Z. ; Zhu, Y. - \ 2015
    Agricultural and Forest Meteorology 214-215 (2015). - ISSN 0168-1923 - p. 483 - 493.
    Ensembles of process-based crop models are increasingly used to simulate crop growth for scenarios of temperature and/or precipitation changes corresponding to different projections of atmospheric CO2 concentrations. This approach generates large datasets with thousands of simulated crop yield data. Such datasets potentially provide new information but it is difficult to summarize them in a useful way due to their structural complexities. An associated issue is that it is not straightforward to compare crops and to interpolate the results to alternative climate scenarios not initially included in the simulation protocols. Here we demonstrate that statistical models based on random-coefficient regressions are able to emulate ensembles of process-based crop models. An important advantage of the proposed statistical models is that they can interpolate between temperature levels and between CO2 concentration levels, and can thus be used to calculate temperature and [CO2] thresholds leading to yield loss or yield gain, without re-running the original complex crop models. Our approach is illustrated with three yield datasets simulated by 19 maize models, 26 wheat models, and 13 rice models. Several statistical models are fitted to these datasets, and are then used to analyze the variability of the yield response to [CO2] and temperature. Based on our results, we show that, for wheat, a [CO2] increase is likely to outweigh the negative effect of a temperature increase of +2°C in the considered sites. Compared to wheat, required levels of [CO2] increase are much higher for maize, and intermediate for rice. For all crops, uncertainties in simulating climate change impacts increase more with temperature than with elevated [CO2].
    Climate variability and change in southern Mali : Learning from farmer perceptions and on-farm trials
    Traore, B. ; Wijk, M.T. van; Descheemaeker, K.K.E. ; Corbeels, M. ; Rufino, M.C. ; Giller, K.E. - \ 2015
    Experimental Agriculture 51 (2015)04. - ISSN 0014-4797 - p. 615 - 634.
    Agricultural production in the Sudano–Sahelian zone of west Africa is highly vulnerable to the impacts of climate variability and climate change. The present study aimed to understand farmers’ perceptions of climate variability and change and to evaluate adaptation options together with farmers, including tactical management of planting date in combination with the use of mineral fertilizer. Farmers perceived an increase in annual rainfall variability, an increase in the occurrence of dry spells during the rainy season, and an increase in temperature. Overall, this is in line with the observed meteorological data. Drought tolerant, short maturing crop varieties and appropriate planting dates were the commonly preferred adaptation strategies to deal with climate variability. On-farm trials confirmed that planting delays significantly reduce crop yields. The use of mineral fertilizer is often promoted, but risky for smallholders: although larger fertilizer applications increased the yield of maize (Zea mays) and millet (Pennisetum glaucum) significantly, a gross margin analysis indicated that it did not lead to more profit for all farmers. We conclude that integrating management of nutrients and planting time with improved farmer access to timely weather information, especially on the onset of the rains, is critical to enhancing adaptive capacity to increased climate variability and change.
    Maize crop residue uses and trade-offs on smallholder crop-livestock farms in Zimbabwe: Economic implications of intensification
    Rusinamhodzi, L. ; Wijk, M.T. van; Corbeels, M. ; Rufino, M.C. ; Giller, K.E. - \ 2015
    Agriculture, Ecosystems and Environment 214 (2015). - ISSN 0167-8809 - p. 31 - 45.
    Decisions to use crop residues as soil cover for conservation agriculture create trade-offs for farmers who own cattle in crop-livestock systems. Trade-offs among soil C, crop and animal and crop productivity were analysed using the NUANCES-FARMSIM (FArm-scale Resource Management SIMulator) dynamic model. Retention on the soil surface of 0, 25, 50, 75 and 100% of the maize stover yield produced per farm, and the use of the remainder as animal feed was quantified over a 12 year period for four farm types in Murehwa, Zimbabwe. Retaining 100% maize residues in the field led to an annual loss of on average 68 and 93 kg body weight per animal for cattle on farms of the relatively wealthiest farmers (Resource Group, RG1) who had most land and cattle and RG2 respectively), and is therefore unsustainable for livestock production. There was an increase in grain yield of 1.6 t farm-1 and 0.7 t farm-1 for RG1 and RG2 respectively. Farmers without cattle (RG3 and RG4) may have a greater incentive for retaining their crop residues but they have to invest labour to keep the residues during the dry season. However, improved crop productivity for these farmers is limited by lack of access to fertiliser. The current practice of allocating all crop residues to animals results in average gross margin of US$7429 and US$4037 for RG1 and RG2 farmers respectively. Our results showed that from an economic perspective, it is logical that farmers prioritise the sustenance of cattle with crop residues over soil fertility management. We conclude that at current productivity levels, farmers who own cattle have limited scope to allocate crop residues for soil cover as it leads to significant loss in animal production and economic value.
    Cotton as an entry point for soil fertility maintenance and food crop productivity in savannah agroecosystems - Evidence from a long-term experiment in southern Mali
    Ripoche, A. ; Crétenet, M. ; Corbeels, M. ; Affholder, F. ; Naudin, K. ; Sissoko, F. ; Douzet, J.M. ; Tittonell, P.A. - \ 2015
    Field Crops Research 177 (2015). - ISSN 0378-4290 - p. 37 - 48.
    organic-matter - nitrogen-fertilization - chemical-properties - nutrient dynamics - semiarid tropics - use efficiency - pearl-millet - burkina-faso - dry-matter - management
    Given the scarcity of manure and the limited land available for fallowing, cotton cultivation with its input credit schemes is often the main entry point for nutrients in cropping systems of West Africa. In an experiment carried out during 25 years in southern Mali, the crop and soil responses to organic fertilizer (=OF), inorganic fertilizer (=IF), and a combination of both (=OIF) were quantified and compared to a control treatment for a typical cotton-sorghum-groundnut rotation. From 1965 to 1979 (15 years, period 1), fertilizers were only applied on cotton and the control treatment was not fertilized. From 1980 to 1989 (10 years, period 2), the amount of manure applied was split between cotton and sorghum, and inorganic fertilizers were applied to the three crops. Inorganic fertilizers were also applied to plots with cotton and sorghum that were previously unfertilized control treatments. In favorable rainfall seasons maximum yields of fertilized treatments reached ca. 3.5 t ha-1 in the case of cotton and groundnuts, and ca. 2 t ha-1 in the case of sorghum. During period 1, cotton yields were steady (ca. 1 t ha-1) when no fertilizers were added. Cotton yields were 20% higher in the OF and OIF treatments than in the IF treatment. Sorghum and groundnut benefited from residual effects of fertilizer application on cotton leading to a 200% and 50% yield increase respectively compared to the control treatment. During period 2, yields of the three crops were similar across fertilized treatments. Groundnut yields in the OF treatment, and cotton yields in the OF and IF treatments were respectively 45%, 30% and 20% significantly higher than those in the respective control treatments. No added benefit on crop yields was observed from the combined use of inorganic and organic fertilizer. Soil nutrient contents (SOC, N, P, K) did not significantly change in any of the treatments after 25 years. Soil pH decreased in treatments receiving inorganic fertilizer. Despite low level of soil organic matter, crops responded to organic or inorganic fertilization and crop productivity over time was mostly influenced by the interaction between fertilization and rainfall variability. Our results highlight the role of cotton in West African landscapes as an entry point of nutrients via fertilization, which impacts positively on the productivity of the other crops in the rotation. Credit schemes by the cotton company for farmers to purchase fertilizer to which they would otherwise not have access are thus crucial for sustained crop productivity.
    Biomass transfers and nutrient budgets of the agro-pastoral systems in a village territory in south-western Burkina Faso
    Diarisso, T. ; Corbeels, M. ; Andrieu, N. ; Djamen, P. ; Tittonell, P.A. - \ 2015
    Nutrient Cycling in Agroecosystems 101 (2015)3. - ISSN 1385-1314 - p. 295 - 315.
    crop-livestock system - management strategies - northern nigeria - farming system - cover change - africa - sahel - vegetation - farmers - forage
    Privatisation of grazing resources is emerging in the agro-pastoral systems of West Africa, resulting in increased pressure on the remaining communal rangelands and greater competition between farmers for access to crop residues. Differential management strategies arise as determined by household diversity. This study quantified the flows of biomass and related nutrient budgets in relation to farm diversity in Koumbia, a representative village of south-western Burkina Faso. Four farm types were identified: subsistence-oriented and market oriented crop farmers, agro-pastoralists and pastoralists. Crop farmers collected about 30 % of their maize harvest residues for feeding during the dry hot season, while agro-pastoralists and pastoralists stocked about 50 % of their maize residues. Whilst the remaining crop residues on (agro)pastoralist farms were almost entirely grazed by their own cattle, about 90 % of the crop residues of crop farmers were consumed by cattle of (agro)pastoralists. On the other hand, available manure from cattle in the village was mainly used to fertilize the fields of the livestock owners. As a result, the cropped land of farmers with few livestock is continuously mined for nutrients. Calculated partial balances of N and K at farm level were negative for all farm types, except for N in the case of pastoralist farms. N and K balances of cropped fields were generally negative on all farm types. Partial balances of P were generally positive, which was to a large extent due to P fertilizer use. Better integration of crop and livestock production activities on farms and between farms offers a pathway to more efficient nutrient cycling with reduced nutrients losses.
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