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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Data from: The plastic fly: the effect of sustained fluctuations in adult food supply on life history traits
Heuvel, Joost van den; Zandveld, Jelle ; Mulder, M. ; Brakefield, P.M. ; Kirkwood, T.B.L. ; Shanley, D.P. ; Zwaan, Bas - \ 2014
Wageningen University & Research
ageing - resource allocation - lifespan - life history - phenotypic plasticity - weight - diet - drosophila melanogaster - reproduction
Many adult traits in Drosophila melanogaster show phenotypic plasticity, and the effects of diet on traits such as lifespan and reproduction are well explored. Although plasticity in response to food is still present in older flies, it is unknown how sustained environmental variation affects life-history traits. Here, we explore how such life-long fluctuations of food supply affect weight and survival in groups of flies and affect weight, survival and reproduction in individual flies. In both experiments, we kept adults on constant high or low food and compared these to flies that experienced fluctuations of food either once or twice a week. For these ‘yoyo’ groups, the initial food level and the duration of the dietary variation differed during adulthood, creating four ‘yoyo’ fly groups. In groups of flies, survival and weight were affected by adult food. However, for individuals, survival and reproduction, but not weight, were affected by adult food, indicating that single and group housing of female flies affects life-history trajectories. Remarkably, both the manner and extent to which life-history traits varied in relation to food depended on whether flies initially experienced high or low food after eclosion. We therefore conclude that the expression of life-history traits in adult life is affected not only by adult plasticity, but also by early adult life experiences. This is an important but often overlooked factor in studies of life-history evolution and may explain variation in life-history experiments.
The predictive adaptive response: modeling the life history evolution of the butterfly, Bicyclus anynana, in seasonal environments
Heuvel, J. van den; Saastamoinen, M. ; Brakefield, P.M. ; Kirkwood, T.B.L. ; Zwaan, B.J. - \ 2012
ecology - evolutionary - evolution - physiological - life history - modeling - individual based - stochastic spatial - phenotypic plasticy - polymorphism - resource allocation - theory - trade offs
A predictive adaptive response (PAR) is a type of developmental plasticity where the response to an environmental cue is not immediately advantageous but instead is later in life. The PAR is a way for organisms to maximize fitness in varying environments. Insects living in seasonal environments are valuable model systems for testing the existence and form of PAR. Previous manipulations of the larval and the adult environments of the butterfly Bicyclus anynana have shown that individuals that were food restricted during the larval stage coped better with forced flight during the adult stage compared to those with optimal conditions in the larval stage. Here, we describe a state-dependent energy allocation model, which we use to test whether such a response to food restriction could be adaptive in nature where this butterfly exhibits seasonal cycles. The results from the model confirm the responses obtained in our previous experimental work and show how such an outcome was facilitated by resource allocation patterns to the thorax during the pupal stage. We conclude that for B. anynana, early-stage cues can direct development toward a better adapted phenotype later in life and, therefore, that a PAR has evolved in this species.
Intrahousehold resource allocation and well-being : the case of rural households in Senegal
Dia, F. - \ 2010
Wageningen University. Promotor(en): Gerrit Antonides; Anke Niehof, co-promotor(en): Johan van Ophem. - [S.l.] : S.n. - ISBN 9789085856863 - 271
agricultural households - resource allocation - household income - time allocation - decision making - households - rural areas - farmers' income - non-farm income - women - men - household expenditure - senegal - gender - well-being - landbouwhuishoudens - middelentoewijzing - gezinsinkomen - tijdsbesteding - besluitvorming - huishoudens - platteland - inkomen van landbouwers - inkomsten van buiten het landbouwbedrijf - vrouwen - mannen - huishouduitgaven - senegal - geslacht (gender) - welzijn
In this last decade, poverty in developing countries remains the most important topic of debate at the international level. The main proposition was how to build policies and programs on a gender perspective approach taking into account gender differences in behavior between male and female at the level of the household. This study is undertaken in a context of two earner partners living in mixed farming systems in Senegal where earnings come primarily from crops and livestock. This book provides substantial research focused on household decision-making regarding resource allocation and consumption. Moreover, it attempts to show empirical findings on the analysis of welfare and well-being through an innovative combination of subjective and objective methods. The research shows how important socioeconomic and cultural factors are in determining earnings from agricultural activities. Important determinants of productivity are related to women’s land access, non-labor income (transfers from migrants), and the wife’s access to credit and health problems. The research illustrates also that women’s bargaining power may be strongly linked to their access to livestock resources, their mobility in purchasing food and medicine and their participation in the management of household finance. Analysis of decision-making regarding expenditures shows that women, more than men, value household goods (related to food, health and schooling expenditures) more than private goods. The results suggest that policies aimed at improving household livelihoods must understand gender differences, obligations and priorities.

Intrahousehold resource allocation and well-being : the case of rural households in Senegal
Dia, F. - \ 2010
Wageningen : Wageningen Academic Publishers (AWLAE series no. 10) - ISBN 9789086861583 - 257
landbouwhuishoudens - middelentoewijzing - gezinsinkomen - tijdsbesteding - besluitvorming - huishoudens - platteland - inkomen van landbouwers - inkomsten van buiten het landbouwbedrijf - vrouwen - mannen - huishouduitgaven - senegal - geslacht (gender) - welzijn - agricultural households - resource allocation - household income - time allocation - decision making - households - rural areas - farmers' income - non-farm income - women - men - household expenditure - gender - well-being
Economics of gender, risk and labour in horticultural households in Senegal
Ndoye, A.F. - \ 2010
Wageningen University. Promotor(en): Erwin Bulte, co-promotor(en): Kees Burger. - [S.l. : S.n. - ISBN 9789085856535 - 254
economie - risico - arbeid (werk) - landbouwhuishoudens - tuinbouw - senegal - ontwikkelingslanden - west-afrika - middelentoewijzing - prestatieniveau - ontwikkelingseconomie - geslacht (gender) - gedrag van huishoudens - economics - risk - labour - agricultural households - horticulture - senegal - developing countries - west africa - resource allocation - performance - development economics - gender - household behaviour
Women play an important role in agricultural production, particularly in Africa, by managing their own farm and by providing their labour to their husband’s fields. Regardless of the predominance of a gender bias with regard to their access to resource, women constitute a vital force in the development of agriculture. Throughout the world, gender issues in the development of agriculture and women’s role and contribution to agriculture continue to be a great subject of debate. Despite the wide range of literature available, the importance of agriculture to the economic development in Africa and the critical role that rural women play within this sector still constitute an attractive research agenda.
In Sub-Saharan African countries, where the majority of the population derives its food and livelihood from agriculture, a strong growth in agriculture is vital for the process of economic development. Agriculture must be the leading sector for overall growth, poverty alleviation, and the reduction of income disparities. In such a context, getting agriculture to move forward is crucial. Particularly with the drastic changes in the world food situation, which affect Africa more than any other region, much more attention should be paid to the supply side of agriculture, both for food crops and market-oriented crops. In fact, cash crops, with high added value products like horticultural products, offer opportunities to boost the agricultural growth in developing countries like Senegal, where horticulture is a key element of the agricultural sector.
Accordingly, with the recent world-wide food trouble, there is a need, more than ever, to examine the economic performance of the agricultural producers, and especially the efficiency of the use of scarce resources, to confront the challenges ahead. However, the key role of women in the agricultural sector in many parts of the world, and particularly in agriculture-based countries like African countries, calls for more gender-sensitive approaches and for policies that take people’s gender identity into account. Jointly, all these reasons widely justify the relevance of this research thesis, which aims to investigate the economic performance of horticultural households in Senegal, using efficiency and profitability as main indicators and adopting a gender perspective.
Efficiency is assessed in a specific social, cultural, economic, and institutional context, in which polygamy occurs and husband and wives usually manage their plots separately. In this context, next to household labour, the labour market offers possibilities to hire labour under two common forms of contract, based on sharecropping or wage. In addition, with the high volatility of the price of horticultural products, the market risk is challenging. Therefore, from this context emerge four main research questions addressed in this thesis, related to (i) the efficiency of the allocation of household resource over men and women, (ii) the efficiency of contracts with hired workers, either as wage labourers or as sharecroppers for household profit optimization, (iii) risk behaviour across gender, and (iv) its effects on the economic performance and the choice of labour contracts. Three chapters (Chapters 3, 4 and 5) provide theoretical and empirical evidence on these research questions, preceded by two chapters (Chapters 1 and 2) setting out the purpose and background of this research.
Chapter 2 describes horticultural households from a gender standpoint, using data collected from a survey of 203 horticultural households in the Niayes Zone in Senegal. We surveyed a total of 422 horticultural plots, managed by 279 producers, of which 190 are men and 89 are women. The households grow a diversity of horticultural crops during the three main seasons. We surveyed five of the most cultivated crops, such as onion, cabbage, tomato, green bean, and potato. All these crops are destined for the national and subregional market. Only green bean is exported to European countries, mainly to France.
This descriptive chapter shows that a household homes 3 to 26 members, with an average of 10. Horticultural households derive their income essentially from horticulture, with a share of 77% of men’s total annual income and 60% of women’s income. Women provide 15% of the household’s total annual income, estimated on average at fcfa 2.1 million. With a daily income per capita of fcfa 575, or 1.3 US dollars, horticultural household members are living slightly above the national poverty line of fcfa 497 and the new extreme poverty threshold of 1.25 US dollars in developing economies.
Household land ownership varies from 0 to 20 hectares, with a median of 3. A great gender gap occurs in particular with regard to the allocation of resource and assets, access to land, and irrigation equipment. Men are the main owners of land and irrigation equipment within the household. In 60% of the households, women are deeply involved in horticulture, managing their own piece of land that has usually been allocated to them by their husband. However, even when they manage their own plots, women and men often work on each other’s plots to carry out hard or time-consuming farming operations. With an average of 460 m2, women’s plots are 4.7 times smaller than men’s plots are. However, regarding the physical conditions of the plot, no major gender discrimination is noticed. With this small plot size, the intensity of the inputs used is higher on women’s plots than it is on men’s plots. As a result, women’s plots yield 17% more in terms of output in value per hectare and 40% more in terms of profit per hectare than men’s plots do.
Horticultural production is so labour-intensive that household labour is not always sufficient and some households take recourse to hired labour. However, while some households hire labour based on a sharecropping contract (31%), others hire labour based on a wage contract (7%). The return per season to sharecropping for a sharecropper is higher on average than the seasonal wage paid by the household to a wage worker. Moreover, the most time-consuming cropping operation is irrigation, which takes 75% and 85% of the total working time of household members on men’s plots and women’s plots, respectively. The time-share of irrigation is on average higher on women’s plots than it is on men’s plots, because women do not have access to improved irrigation equipment like a motor pump. The horticultural marketing context is characterized by a high variability of the output price, which is a major risk. For the same plot and crop, the selling price of the production varies greatly from one harvesting sequence to the next one, which takes just a few days. Altogether, the descriptive chapter brings to light the research issues addressed in the following chapters.
Chapter 3 replies to the first research question by examining the efficiency of household resource allocation. It furthermore deals with the appropriateness of using gender-specific models rather than a unitary model while investigating the economic performance of male and female managers of separate plots within horticultural households. Therefore, chapter 3 contributes to the gender and economics literature, providing empirical evidence regarding intra-household resource allocation in a polygamous context in which husband and wives manage their plots separately.
Both the unitary and gender-specific stochastic frontier production functions show that women plot managers are as technically efficient as men plot managers are, but neither the men nor the women are fully technically or allocatively efficient. The determinants of technical inefficiency effects present some similarities as well as some differences between men and women plot managers. Furthermore, based on gender-specific models, the value of the marginal product of land and irrigation equipment is higher on the women’s plots than it is on the men’s plots, while the value of the marginal product of inputs and labour is higher on the men’s plots than it is on the women’s plots within the same household.
We can conclude from the findings that optimality or allocative efficiency from a household perspective is far from being achieved for all the inputs. Some improvements can be made by shifting land and irrigation equipment from men to women and by shifting inputs and labour from women to men. However, given that both men and women are allocatively inefficient in the use of inputs, rather than to shift, it is better to scale up the inputs used in order to reduce the inefficiency. Since households are cropping on average 59% of their available land, there are some possibilities or potentialities to scale up the cropped area, but this is conditional on a better access to labour-saving irrigation equipment. This suggests some policy implications, which must be more gender-sensitive, to improve both men’s and women’s ability to manage their productive resource more efficiently. A better access of women to land and to improved irrigation equipment will be a lever to improve women’s economic performance and, consequently, both their own well-being and the whole household’s welfare.
The second research question is addressed in Chapter 4. In agriculture, the coexistence of different forms of land tenancy or labour contract have so far been explained by theories related to Marshallian inefficiency, incentives, risk sharing, and transaction costs, including the costs of supervision. These theories and the empirical evidence have greatly contributed to explain the reasons behind land tenancy or labour contract choice. This study goes a step further by focusing particularly on production technologies at plot level. This study provides theoretical and empirical evidence by designing and testing a model based on household profit optimization (i) to compare the optimum profit derived from plots under household labour, a sharecropping labour contract, or a wage labour contract, and (ii) to test the efficiency of the labour choice made, controlling for the irrigation equipment used on the plot. The model does not account for risk behaviour, but focuses mainly on the supervision costs of labour under a wage contract, and on opportunity wages ratios of the sharecropper and the wage worker, of the sharecropper and the landlord, and of the wage worker and the landlord. In order to test the efficiency of the labour contract choice, for each plot, simulations were made to see if another labour contract than presently applied would yield a higher profit to the household.
As expected, the results show that the production elasticity of labour decreases when improved irrigation equipment like a motor pump is used. The technology displays an increasing return to scale on plots without a motor pump and a constant return to scale on plots irrigated with a motor pump. While on plots without a motor pump a sharecropping contract is the efficient labour contract choice, leading to a higher optimum profit for household, on plots irrigated with a motor pump, a wage contract is the best labour contract choice. Consequently, we can conclude from this finding that the use of a motor pump drives out the sharecropping contract in favour of household labour and the wage labour contract. Unless the commonly applied sharing rules, 50-50 of the profit, change with a greater share for the landowner, with the increasing use of labour-saving technologies, households will be less and less willing to hire labour under a sharecropping contract.
Chapter 5 theoretically and empirically investigates the risk issues. Agricultural production is typically a risky business. Farm households have to tackle several risks. For this reason, farm households’ risk attitude is an important issue connected with decision making and greatly affects their economic performance. In Senegal, for horticultural households, the output market price is one of the foremost risks. Moreover, within the household, husband and wives may behave differently towards risk. This research provides theoretical and empirical evidence regarding the measures and effects of risk attitude on economic performance and on the choice of inputs across gender. More precisely, based on an experimental game implemented in the Senegalese Niayes Zone, this chapter investigates the gender dimension of risk attitude and the causal relationship between risk attitude, allocative inefficiency of the choice of inputs, and decisions regarding the choice of labour contract.
The results show that, on average, men and women producers display an absolute risk aversion towards the output market price, and that women are as risk averse as men. As expected, and in line with the theoretical model, the empirical evidence shows that allocative inefficiency in the use of inputs increases with risk aversion. Moreover, the empirical evidence confirms the theoretical model propounding that if producers are more risk averse, they prefer to hire labour based on a sharecropping contract rather than on a wage contract. We identify recommendations for policy decision makers in terms of strategies that may help to make men and women producers more risk-neutral towards the output market price and to dampen the repercussions of risk for efficiency.
All in all, this thesis innovatively provides theoretical and empirical evidence to add to the body of the literature of the economics of household resource allocation, with a special focus on gender, labour and risk. In addition to its scientific contribution, the thesis puts forward to decision makers a number of recommendations for a better economic performance of horticultural households with women playing a leading role, as this is in favour of household welfare. Although agricultural growth driven by horticulture is a challenge for economic growth and poverty alleviation, it is potentially achievable.
















Msimu wa Kupanda : targeting resources within diverse, heterogenous and dynamic farming systemes of East Africa
Tittonell, P.A. - \ 2008
Wageningen University. Promotor(en): Ken Giller, co-promotor(en): B. Vanlauwe; Mark van Wijk. - [S.l.] : s.n. - ISBN 9789085048077 - 320
bedrijfssystemen - bodemvruchtbaarheid - middelentoewijzing - systeemanalyse - simulatiemodellen - kringlopen - voedingsstoffen - stikstofkringloop - organisch bodemmateriaal - kenya - uganda - afrika ten zuiden van de sahara - bodemvruchtbaarheidsbeheer - farming systems - soil fertility - resource allocation - systems analysis - simulation models - cycling - nutrients - nitrogen cycle - soil organic matter - kenya - uganda - africa south of sahara - soil fertility management - cum laude
cum laude graduation (with distinction)
Optimising import phytosanitary inspection
Surkov, I. - \ 2007
Wageningen University. Promotor(en): Alfons Oude Lansink; Olaf van Kooten, co-promotor(en): Wopke van der Werf. - S.l. : s.n. - ISBN 9789080547018 - 169
plantenplagen - quarantaine - inspectie - optimalisatie - plagenbestrijding - import - middelentoewijzing - plant pests - quarantine - inspection - optimization - pest control - imports - resource allocation
Keywords: quarantine pest, plant health policy, optimization, import phytosanitary inspection, ‘reduced checks’, optimal allocation of resources, multinomial logistic regression, the Netherlands World trade is a major vector of spread of quarantine plant pests. Border phytosanitary inspection is a major barrier against introductions of quarantine pests through imported commodities, although the inspection resources are limited. This thesis provides conceptual and empirical insights that may help optimise import inspection under limited resources. The developed conceptual models analysed inspection policies under capacity constraints and in the absence of capacity constraints. The empirical models focused on finding the optimal inspection policies of propagating materials imported in the Netherlands. The results indicate that inspection effort should focus on commodities, whose inspection yields ceteris paribus greater marginal reduction in the expected costs of pest introduction. The results show that under binding capacity constraints, inspection of chrysanthemum cuttings in the Netherlands has a high marginal benefit, ranging from 8 to 49 euros for every marginal euro of inspection cost. The results further indicate that in the presence of fixed inspection costs, attaining the unconstrained allocation of inspection effort from the current, capacity constrained levels, is relatively inexpensive and greatly reduces costs to society. To expand current inspection capacities, the costs and likelihoods of pest introduction should be carefully estimated. Using the developed models for optimal allocation of inspection resources, the efficacy of the ‘reduced checks’ import inspection system in the EU was analysed. The results indicate that the expected costs of pest introduction in the EU under reduced checks could further be reduced if the economic impacts of pest introduction through various commodities are accounted for when calculating the frequencies of reduced checks. Finally, a multinomial logistic model was developed to analyse factors that determine the likelihoods of rejecting imported commodities due to phytosanitary and non-phytosanitary reasons. The results suggest that the geographical position of the exporting country, the characteristics of the importing company, the size of imported shipments, and the intended use of the commodity, among others, are significant factors based on which shipments of plant commodities can be targeted for inspection. Inspecting agencies can considerably facilitate the design of optimal inspection frameworks for the management of import phytosanitary risks by sound data-recording procedures that enable scientific analysis and provide a solid basis for reliable and applicable results.
Residual feed intake in young chickens : effects on energy partitioning and immunity
Eerden, E. van - \ 2007
Wageningen University. Promotor(en): Bas Kemp; Mart de Jong, co-promotor(en): Henry van den Brand. - [S.l.] : S.n. - ISBN 9789085045939 - 168
jonge kippen - voeropname - efficiëntie - middelentoewijzing - energiegebruik - experimentele infectie - immuniteitsreactie - immuniteit - pullets - feed intake - efficiency - resource allocation - energy consumption - experimental infection - immune response - immunity
Changing properties of property
Benda-Beckmann, F. von; Benda-Beckmann, K. von; Wiber, M. - \ 2006
London : Berghahn Books - ISBN 9781845451394 - 367
law - social anthropology - property rights - resource allocation - culture - common lands - common property resources - recht - sociale antropologie - eigendomsrechten - middelentoewijzing - cultuur - gemeenschappelijke weidegronden - gemeenschappelijk bezit
The allocation of scarce resources in miscellaneous cases
Hamsvoort, C.P.C.M. van der - \ 2006
Wageningen University. Promotor(en): Henk Folmer; L.C. Zachariasse. - [S.l. ] : S.n. - ISBN 9789086150526 - 126
middelentoewijzing - hulpbronnen - economische theorie - duurzaamheid (sustainability) - veilingen - landbouwgrond - grondmarkten - handelsonderhandelingen - milieu - landgebruiksplanning - schaarste - resource allocation - resources - economic theory - sustainability - auctions - agricultural land - land markets - trade negotiations - environment - land use planning - scarcity
Simulating the partitioning of biomass and nitrogen between roots and shoot in crop and grass plants
Yin, X. ; Schapendonk, A.H.C.M. - \ 2004
NJAS Wageningen Journal of Life Sciences 51 (2004)3-4. - ISSN 1573-5214 - p. 407 - 426.
grassen - tarwe - plantenfysiologie - biomassa - stikstof - wortel spruit ratio - middelentoewijzing - grasses - wheat - plant physiology - biomass - nitrogen - root shoot ratio - resource allocation - elevated carbon-dioxide - vegetative plants - leaf-area - dry mass - growth - model - co2 - allocation - ratios - water
Quantification of the assimilate partitioning between roots and shoot has been one of the components that need improvement in crop growth models. In this study we derived two equations for root-shoot partitioning of biomass and nitrogen (N) that hold for crops grown under steady-state conditions. The equations are based on the concept of the functional balance between N uptake by roots and carbon fixation by shoots, and incorporate the assumption that plants control their root-shoot partitioning in order to maximize relative growth rate. The equations do not have their own parameters but use several variables as inputs that can be calculated from sub-models for root N uptake and shoot carbon fixation in a general plant growth model. Given reports from the literature that the partitioning models – if expressed as a function of plant-N status – might be suitable for steady-state as well as non-steady-state conditions, our equations were deliberately applied to non-steady-state conditions. The predicted crop root-shoot partitioning and its responses to radiation, water and N agreed qualitatively with the expected trends. The predicted response to elevated carbon dioxide varied and depended on the timing and amount of N applied. Quantitative tests with data from root and shoot pruning experiments with grass plants carried out by others showed that model predictions also agreed with observed root-shoot ratios, suggesting that our equations provided a valuable semi-mechanistic approach to the prediction of rootshoot relationships under any growth conditions.
Spatial variability and farmer resource allocation in millet production in Niger
Gandah, M. - \ 1999
Agricultural University. Promotor(en): J. Bouma; J. Brouwer; A. Stein. - S.l. : S.n. - ISBN 9789058080790 - 115
parelgierst - pennisetum glaucum - bodemvariabiliteit - middelentoewijzing - bodembeheer - methodologie - niger - pearl millet - pennisetum glaucum - soil variability - resource allocation - soil management - methodology - niger

The Sahel of West Africa is the agro-ecological zone located between 12 oand 16 oN, with an annual rainfall of between 300 and 1000 mm. Crops are grown in a subsistence type of agriculture during the 75 to 125 days growing period between May and September. Major crops are millet, sorghum, cowpea, and groundnut, sown usually in mixed-cropping. Crop production suffers from frequent droughts and poor soil fertility, which cause low yields and repeated food shortages. Traditional farming, in the western part of Niger, relies on the use of livestock to combat soil nutrient deficiencies, and other risk minimizing strategies, to produce an average 350 kg ha -1year -1of millet grain. This is the context within which this research was conducted in four localities in western Niger in 1995, 1996, and 1997.

The overall aim was to investigate soil and crop variability at various scales and the rightness of traditional land management in millet cropping subject to extremely variable weather conditions. The main objectives were:

  1. to test and refine the hill scoring technique for characterizing within field soil and crop yield variability in 3 localities of western Niger
  2. to identify soil properties explaining yield variability in space and time
  3. to evaluate the effects on millet yield of site specific management of manure and fallow in a Fulani farmer's field
  4. to compare management systems used by farmers in four different landscape positions
  5. to describe farmers methods of land evaluation and management options, based on farmers' expert knowledge of the environment

Within-field soil and crop variability are discussed in chapters 2 and 3. Grain and straw yields varied considerably within-field at each of the three sites, and also between sites and between years. In 1996, grain yields varied from 8-383 kg ha -1, 2-1343 kg ha -1, and 7-815 kg ha -1at the three sites along a 400 km N-S gradient. The coefficient of variation at the three sites was 61, 55, and 53% respectively. Only 5 to 28% of the yield variability could be explained by soil chemical properties. Other factors such as micro-topography and water redistribution also made yields vary over short distances according to several studies in the region. A millet hill scoring method was tested and refined to obtain yield estimates before crop harvest. Scoring studies have remained at the row or plot level as opposed to the individual hill level. The method was simple and was able to explain up to 67% of the yield variation. Yield variation between years was least at the drier northern site with poorer soil and yields. Variation in yields among years was most closely correlated with soil pH and Al in the northern and central sites, whereas P was the best in explaining grain yield differences in the southern site.

Chapter 4 deals with land management at the individual household level. Soil and crop management were investigated in two fields owned by a Fulani household. Management practices created man-made variability in the fields. Soil nutrient contents were improved in patches through the use of field corralling of livestock and fallow. Quantities of manure applied at specific sites varied from 1500 to 17000 kg ha -1. Corralling increased yields from 500 to 1100 kg ha -1, but amounts of manure applied were too high in some spots and losses were likely to occur through leaching. Nutrients and pH changes in the soil profile were found to change appreciably over time following the application of manure or of fallow. Based on the results obtained, an improvement in the farmer's management can be achieved by spreading manure to an area 3 to 5 times larger than the area actually used.

Chapter 5 focuses on farmers' land management practices according to landscape position. Contrary to common belief, soils on the plateau were richer than soils on other landscape positions, which were cropped continuously and had a sandier texture. Plateaus, however, showed limitations such as low infiltration of rainfall and were located relatively far away from villages. Fields on undulating terraces and valleys had the highest number of different management practices, among which the use of livestock corralling and fallow were the most important.

Chapter 6 considers social aspects of soil management, through the use of ethno-pedology by farmers in ordinary cropping activities. Farmers' knowledge of the land, plants and weather is described as well as the use of this knowledge by farmers in millet production. Simple soil descriptors such as texture, color, surface condition and indicator plants have been used by farmers to evaluate the land. Management practices rely on local knowledge regarding variability in soil fertility and water availability as a guide to implement crop management decisions and to design risk reducing strategies. These compensate in part for the lack of external inputs. The value of ethno-pedology for modern research is that it can serve to better identify farmers' needs and, as a result, improve research quality and the effective communication of results obtained. However, limitations in the use of ethno-pedology exist and they include its inability to quantify factors and the confusion between causes and effects for processes not well understood by farmers.

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