Agroforestry Systems 59: 317–326, 2003.© 2003 Kluwer Academic Publishers. Printed in the Netherlands.

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Adoption of improved fallow technology for soil fertility management inZambia: Empirical studies and emerging issues

O.C. Ajayi1,∗, S. Franzel2, E. Kuntashula1 and F. Kwesiga3

1International Centre for Research in Agroforestry (ICRAF)–Government of Zambia Agroforestry Project, P.O.Box 510046, Chipata, Zambia; 2ICRAF, P.O. Box 30677, Nairobi, Kenya; 3ICRAF Southern Africa Re-gional Programme, P.O. Box MP 128, Mt. Pleasant, Harare, Zimbabwe; ∗Author for correspondence (e-mail:o.c.ajayi@cgiar.org; fax: +260-6-221404)

Key words: Natural resource management, Nutrient deficiency, Planted fallows, Southern Africa, Sesbania,Sustainable agriculture

Abstract

In the subsistence-agricultural region of eastern Zambia, less than 10% of the households have adequate supplyof maize (Zea mays L.), the staple food, throughout the year. A major constraint to increasing crop productionin the region is poor fertility status of the soil. In order to address this problem, improved fallow has beenintroduced as a technology for improving soil fertility within a short span of two to three years. Farmers havebeen testing the technology and a number of empirical studies have been undertaken over the years to identifythe factors influencing farmers’ decision to adopt the technology. This paper presents a synthesis of the resultsof adoption studies and highlights generic issues on the adoption of improved fallows in Zambia. The synthesisindicates that farmers’ decision on technology adoption does not have a simple directed relationship of some tech-nological characteristics only, but constitutes a matrix of factors including household characteristics, communitylevel factors, socioeconomic constraints and incentives that farmers face, access to information, local institutionalarrangements and macro policies on agriculture. The adoption of improved fallows is not strictly speaking a binarychoice problem but a continuous process in which farmers occupy a position along a continuum in the adoptionpath. Further, adoption of improved fallows may not take place in a policy vacuum but needs to be facilitated byappropriate and conducive policy and institutional incentives. Several questions and issues that require further studyemerge from the synthesis. These include determination of the relative importance of the factors in the adoptionmatrix, identification of the conditions under which farmers use a combination of inputs and their profitabilityunder changing price scenarios, exact definition to delineate between ‘non-adopters’, ‘testers’ and ‘adopters’ ofagroforestry technologies, and understanding the impact of cash crop farming in farmers’ adoption decisions ofimproved fallows (where off farm opportunities exist). Further, there is a need to determine the inter-relationshipbetween household poverty, labor availability and the adoption of improved fallows and, to evaluate a combinationof policy interventions at both national and local level to promote the adoption of agroforestry-based soil fertilitymanagement.

Introduction

One of the greatest biophysical constraints to in-creasing agricultural productivity in Africa is the lowfertility of the soils (Bekunda et al. 1997; Sanchezet al. 1999). The need to improve soil fertility man-agement in the continent has become a very importantissue in the development policy agenda (Scoones and

Toulmin 1999) because of the strong linkage betweensoil fertility and food insecurity on one hand andthe implications on the economic well being of thepopulation on the other. Eastern Zambia representsa case study where this linkage is particularly welldemonstrated. Peterson (1999a) reports that only 4%of the households in eastern Zambia had enough maize

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(the staple food) to feed their members throughoutthe year. Other farmers depended on food donations(commonly referred to as ‘relief maize’) or purchasedmaize. Among other factors, one of the major reasonsfor this situation is low crop productivity arising fromlow soil fertility base and degradation of soils overseveral years (Kwesiga et al. 1999). The degradationof soils is caused by two related factors: (i) breakdownof the traditional production systems resulting fromshortening of the fallow periods arising from popu-lation pressure and (ii) low adoption of sustainableresource management strategies.

In response to these challenges, researchers in-troduced improved fallow as a sustainable option toreplenish soil fertility within the shortest possibletime (Kwesiga et al. 1999). Improved fallow involvesplanting of fast growing plant species that are (usu-ally) nitrogen-fixing, produce easily decomposablebiomass, compatible with cereal crops in rotation andare adapted to the climatic and edaphic conditionsof the miombo woodland ecology of southern Africa(Kwesiga and Coe 1994). The major species that havebeen found to be suitable for improved fallows in east-ern Zambia are Sesbania sesban (L.) Merr., Gliricidiasepium (Jacq.)Walp., Tephrosia vogelii Hook. f. andCajanus cajan (L.) Millsp.. Following the confirm-ation of the biophysical feasibility and performanceof improved fallows after several years of research,the technology has been successfully tested in farm-ers’ fields and currently more than 25 000 farmers areusing the technology in Zambia (A. Boeringer, pers.comm.). In an effort to scale up the adoption of thetechnology to many more households who are poten-tial beneficiaries of the technology, several questionsregarding the adoption of the technology are beingasked by investors, development workers and partners.These questions include: which category of farmersadopt /do not adopt the technology?; what factors driveadoption of improved fallow technology? and, whydo some continue to adopt more than others? Fran-zel (1999) hypothesized the relationship of selectedfarm and household characteristics to the adoption ofimproved fallows but noted the lack of empirical stud-ies. More recently, a number of empirical studies havebeen carried out to understand farmers’ decision toadopt the technology or otherwise.

The objectives of this paper are: (1) to synthes-ize the findings of empirical studies on the adoptionof improved fallows in Zambia, (2) to highlight themain lessons learnt and (3) to identify generic issuesthat have emerged from the various studies. The paper

highlights areas for further research and also drawsimplications of the findings of the studies for policyand scaling up of improved fallow technology in theregion. Zambia was chosen as appropriate location tosynthesize the knowledge gained regarding farmers’adoption decision on improved fallows because moston-farm work on improved fallows took place there. Inaddition, the highest number of testers and adopters ofimproved fallow are located in the country and, mostof the empirical studies on adoption in the southernAfrica region took place in Zambia.

Overview of eastern Zambia

Eastern Zambia lies between latitude 10◦ to 15◦ S andlongitude 30◦ to 33◦ E bordering Malawi to the east,and Mozambique to the south. It covers 70 000 km2,or about 9% of the total territory of Zambia. The alti-tude in this area ranges from 900 to 1200 m above sealevel. Eastern Zambia has three distinct seasons: warmwet season or agricultural season from November toApril; cool and dry season from May to August andhot and dry season in September and October. The av-erage annual rainfall is 1000 mm and most of the rainsoccur between December and March. The length ofthe growing season varies from 139 to 155 days. Thevegetation is typical of the eastern and central plateaumiombo woodland. The main crops including maize,sunflower, peanuts, cotton and vegetables are cultiv-ated in small fields usually less than 2 ha. Farm sizesaverage about 4 ha with half of the farm under fallow(Peterson et al. 1999a). Some households also engagein agro-pastoral farming. The province is largely ruralwith about 91% of the population living in the ruralarea. The major ethnic groups are Ngonis, Chewas,Nsengas and Tumbukas.

Synthesis of empirical studies

Since the early nineties when on-farm trials and farm-ers’ testing of the improved fallows began, differentinvestigators have carried out a number of empiricalstudies to assess the adoption of the technology. Anoverview of the studies synthesized and their mainresults are presented in Table 1 while the synthesis isgiven below:

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Table 1. Factors affecting farmers’ decisions to plant and continue planting improved fallows in eastern Zambia.

Study Wealth Age Gender Educa- Labor/ Farm Uncul- Use of Off- Oxen Village

tion House size tivated fertili- farm owner- exposure

-hold land zer income ship to

size improved

fallows

Factors affecting decision to plant

Franzel (1999) N N

Phiri et al. (2003) + N +Kuntashula et al. (2002) + N N + N N +Ajayi et al. (2001) N +,N N +Peterson et al. + + +(1999b)

Factors affecting decision to continue to plant

Keil (2001) +/− N N N + +Place et al. (2002) + N N N N +

Notes: N: no association with planting improved fallows, +: positive association, –: negative association, +/−: positive or negativedepending on the value, Blank means the variable was not tested.

Factors influencing the establishment of improvedfallows

Using information collected at the early developmentstage of improved fallows, Franzel et al. (2002) re-viewed several surveys of farmers involved in on-farmtrials of improved fallows. For the 157 researcher-designed, farmer-managed trials begun in 1994–1995,four surveys were conducted over a two-year periodto determine farmers’ assessments and uptake of thetechnology. A study was also conducted of farmers in-volved in farmer-designed, farmer-managed trials, thatis, trials in which farmers experimented with improvedfallows on their own involving management practicesappropriate for farm conditions. Labor supply did notnecessarily prevent farmers from testing improved fal-lows but it posed an important limitation to the areathat a farmer allocates to the technology. The studyalso found that the technology was gender-neutral,i.e. women were planting them about as frequentlyas men. However, women were planting significantlysmaller plots than men. Despite having access to suf-ficient amounts of seed and seedlings similar to men,women planted smaller plots probably because of riskaversion or lack of labor.

Phiri et al. (2003) surveyed 218 households infour villages in 1998. The villages were selected tak-ing into cognizance their contrasting features thusproviding information regarding how farmers in dif-ferent village circumstances react to the testing ofimproved fallows. Farmers classified themselves into

wealth groups and the report focuses on the asso-ciation between wealth status, gender, and plantingof improved fallows. The influence of wealth status,gender, and village on planting of improved fallowswas assessed using a linear-logistic model for orderedcategory response data. The study found some evid-ence of association between planting improved fal-lows and farmers’ wealth. The use of fallows washigher among wealthier households, with 53% of thewell-off farmers using improved fallows comparedto 16% among the very poor households. The ana-lysis revealed little difference in the level of continuedadoption of improved fallows between men and wo-men (32% and 24% respectively). There were nosignificant differences between the proportions of wo-men and men planting improved fallows or betweensingle women and female heads of households whowere married. The study did not find any barrierpreventing low-income households from establishingimproved fallows. Rather, poor farmers appreciatedimproved fallow because it helped them to substituteland and labor (sourced ‘free’ from within the house-hold) for direct cash that was relatively scarcer in ruralhouseholds.

Kuntashula et al. (2002) examined factors influen-cing decisions to plant improved fallows among thesame 218 farmers sampled by Phiri et al. (2003). Us-ing chi-square and t-tests on data collected in 1998,the authors tested the existence of association betweenplanting improved fallows and several farm and house-hold characteristics. Ownership of oxen and size of

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available land holding were positively associated withthe establishment of improved fallow plots. Farmerswho did not plant improved fallow attributed their de-cision to inadequate labor resources, shortage of land,lack of exposure to the technology, non-membershipin farmer groups or that they belonged to cooperativegroups whose objectives were not related to soil fer-tility management. Factors such as age, marital status,formal education, hiring or selling of labor, possessionof iron roofed house, uncultivated land and regularoff-farm income were not significantly associated withplanting of improved fallows.

Peterson (1999a) conducted a baseline survey of320 randomly selected households, of which 230 weremale-headed and 90 female-headed. The survey wasconducted across five districts to assess farming prac-tices and other information that were hypothesizedto be affected by a new USAID-financed project.Approximately 23% of the farmers who planted an im-proved fallow adopted the technology. Peterson foundthat farmers would plant improved fallow if they havethe resources to do so. These ‘resources’ include pa-tience (ability to wait two years to reap the benefits),knowledge, seeds, strength, time, land, and authorityover important farm decisions. The main constraintsto planting an improved fallow were: lack of aware-ness, lack of technical knowledge of how and whento plant and lack of seeds/seedlings. Access to landand time to plant an improved fallow were not majorconstraints. However, the inability to wait two years tosee the benefits was a major constraint for some farm-ers. In contrast to Phiri et al. (2003), the study foundthat proportionately more men planted improved fal-low than women primarily because married womenneed the consent (authority) of their husbands be-fore planting trees but not vice versa. The differencesbetween the results obtained by Phiri et al. (2003)and Peterson (1999a) may indicate the importanceof dis-aggregating data analysis on adoption withinhouseholds by gender.

Using the data as that mentioned above by Peterson(1999a), Ajayi et al. (2001) followed up the analysisto delineate the typology and the characteristics of thefarmers who planted improved fallows, and to determ-ine in what ways they differed from farmers who didnot plant improved fallows. The analysis was basedon a binary analysis using general linear model. Theresults showed that contrary to theoretical expecta-tions, gender; household size and the size of maizefield do not significantly influence farmers’ decisionsto establish improved fallows. The non-significance of

household size indicates that the effective number ofhousehold members available to carry out farm workis more important than the nominal number of house-hold members. This is because households that havemore effective field workers are less constrained bythe extra labor required to work in improved fallowfields (in addition to their usual maize and other cropfields) and therefore tend to test improved fallows themore. Farmers who plant improved fallows are charac-terized by membership in farmers’ cooperative groups.They have all obtained information on how trees im-prove soil fertility prior to deciding to establish animproved fallow field and in addition, such farmerstypically have relatively abundant labor available tothem. In some cases there was a joint adoption demandfor agroforestry technology and ‘modern’ agriculturalinputs because farmers who used significantly higheramounts of modern farm inputs (e.g. improved seeds)also planted improved fallows. The use of moderninputs most probably measures the level of innovat-iveness or farmers’ desire to try out new technologies.The study did not find any evidence of conflicts in theadoption of improved fallow by farmers who used fer-tilizers and, in some cases there appeared to be a jointadoption demand between fertilizers and agroforestry-based soil fertility improvement practices. There wasa positive relationship between cotton cultivation, useof fertilizer and the adoption of improved fallows.

Peterson (1999b) used ethnographic decision treesto assess the decisions of 121 small-scale farmers(40 male and 81 female) who had planted improvedfallows. The study was conducted in four villages se-lected for their contrasting features, where farmershad access to information and germplasm for testingimproved fallows. The results indicated that farmerswere motivated to plant improved fallows because ofthe high price of fertilizer and lack of access to cashto purchase it, recognition of low soil fertility as animportant constraint to crop production, visual verific-ation of the benefits of the technology and an innatedesire to try out new things. The probability to es-tablish improved fallows was higher for farmers whowere wealthier (probably because they could affordto take greater risk to try an ‘unknown’ technology),who belonged to farmers’ clubs, had access to moreland and possessed oxen. Farmers who did not plantimproved fallow attributed their decision to labor con-straints, lack of access to land and unwillingness towait for two years before realizing the benefits of thetechnology.

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Factors influencing farmers’ decision to continueplanting improved fallows

Another group of adoption studies has focused onthe underlying decision of farmers to continue toplant improved fallows after initially establishing one.These studies defined adoption as the planting of asecond fallow after observing the performance of thefirst one. Keil (2001) examined the experiences of100 randomly selected farmers from four camps inChipata North and Chipata South districts, focusingon whether or not initial testers go on to adopt thepractice. The survey was conducted in 2000–01; onlyfarmers who had planted improved fallows during1996–97 or earlier were sampled, as these farmerswere most likely to have had sufficient experience todecide whether or not to adopt. The author used aprobit model to determine factors affecting the de-cision whether or not to adopt improved fallows andthen used a two-step least squares model to assessfactors affecting the adoption and area planted to im-proved fallows. The analysis indicated a non-linearrelationship between continued adoption of improvedfallows and wealth status of farmers. Adoption in-creased up to a certain wealth level, beyond whichit dropped sharply. Ninety-three percent of the fairlywell-off farmers adopted improved fallow, as opposedto only 76% of poor farmers, and 58% of very poorand well-off farmers. The well-off farmers adopted ata lower rate than the fairly well-off, probably becausethey had the financial resources necessary for buy-ing fertilizer. Further, belonging to the fairly well-offstratum positively influenced the intensity of adop-tion. However, personal characteristics including age,gender and education were not significantly associatedwith adoption of improved fallows. The intensity ofadoption (i.e., proportion of the total cultivated areaplanted to improved fallow) decreased with increasingage of the household head, probably due to higher riskaversion by older farmers.

In a separate study, Place et al. (2002) examinedfactors affecting the continued use of improved fal-lows as compared to two other soil fertility replenish-ment options, chemical fertilizer and animal manure.The sample was 101 farmers who first tested improvedfallows in 1994–1995, selected from a sample of 157farmers who volunteered to test the practice in thatyear. None of the household-specific variables wassignificantly related to continued use of the improvedfallows. The technology appeared also to be neutralwith respect to gender. However, two community level

variables, residence of household in pilot dissemina-tion villages and the location of the camp, significantlyaffected the continued adoption of improved fallows.These variables appeared to have similar impacts onall types of households within the communities. Themost important was whether the household residedin one of the pilot villages having access to greaterattention and technical advice from agroforestry insti-tutions. The second was higher adoption rate in onearea than the others due to unknown reasons. It is ex-pected that in the future, use of improved fallows willbe determined by variables that are reflective of farmerdemand rather than by farmers’ village location.

Institutional and policy factors affecting the decisionto plant improved fallows

The third set of adoption studies examined how in-stitutional and policy factors that are ‘external’ toindividual farmer and technological characteristics in-fluence the adoption of the technology. Using a com-bination of rapid rural appraisal technique, expertsurveys, village workshops and formal surveys, Ajayiet al. (2002) assessed the level of implementation andeffectiveness of the existing local bylaws on the insti-tutional constraints against the adoption of improvedfallow in eastern Zambia. Fire and grazing were thefocus of the study because these are the major con-straints that were addressed by the bylaws. The studyidentified the variation in the implementation of thelaws across the major geo-cultural blocs in easternZambia and examined the factors that explain the cur-rent level of the effectiveness of the bylaws amongthe farming communities. The results showed that theeffectiveness of the bylaws against fire and browsingvary depending on the type of cultural community in-volved and the level of agro-pastoral farming. Theeffectiveness of the bylaws was found to be gener-ally low due to several factors. These include lack ofunderstanding of the exact provisions of the bylawsby the various components of the community, lackof clearly defined roles and responsibilities to en-force the bylaws, conflicting economic interests ofthe different groups within the community especiallybetween farmers practicing improved fallows and live-stock rearing. The study recommends a formal doc-umentation of the laws, need for building consensusamong the different interest groups in the communitythrough policy dialogues among all stakeholders in-cluding livestock and other non-agroforestry farmers.The dialogue should provide continuous feedbacks to

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traditional authorities regarding the bylaws, and helpto improve the effectiveness of the bylaws.

Summary of the synthesis

The factors affecting the adoption of improved fal-lows can be grouped into four broad categories basedon the nature of their influence on farmers’ adoptiondecision: (1) factors exerting positive influence, (2)factors having negative impacts, (3) factors having am-biguous or no direct effect, and (4) factors that arecommunal in nature which exert significant impactson all types of households over wide spatial locations(Table 2).

The summary table indicates that enhancement ofthe adoption of improved fallows will necessarily in-clude efforts to reinforce those factors that positivelyaffect farmers’ adoption and minimizing those thatnegatively impact. In addition, efforts should be madeto facilitate an enabling policy environment that isconducive to the adoption of improved fallow at thelocal and national level.

Emerging issues on adoption of improved fallows

Various issues and questions have emanated fromthe empirical studies synthesized in this paper thathave implications for future research and policies onthe adoption of improved fallow and natural resourcemanagement in general. These are classified into sixgeneric issues and discussed below.

First, the studies reveal that adoption does nothave a simple direct relationship with technologicalcharacteristics but rather it is a matrix of severalhierarchies of other factors. These factors include gov-ernment policies on fertilizers, availability of institu-tional support and services, information linkages andnetworks and the socio-economic constraints and in-centives that farmers face. Farmers’ adoption decisionon agroforestry is governed by interplay of macro-level (systemic) and individual-level factors ratherthan one single type of factors (McDonald and Glynn1994). There is however a need to identify the rel-ative influence of household-specific variables (e.g.,age, education), village-wide and community-levelfactors (e.g., presence of non-governmental organiza-tions (NGOs), accessibility to markets) and systemicvariables (e.g. land tenure system, institutional andagricultural policies) on the adoption of agroforestry.This approach was used in a recent study (Place et al.

2002). It is justified by the fact that the adoptionof technologies requires not just the assessment ofindividual farmer choice and aggregating to a lar-ger level, but also consideration of how the wholeaffects the individual choices. An understanding ofthe above relationship will provide insights into ap-propriate strategies for the scaling up of agroforestrytechnology: e.g., should the scaling up of agroforestryfocus on geographical areas possessing the necessarycharacteristics that are conducive to the adoption ofagroforestry or should individual farmers who possessthe ‘right’ characteristics in any community be thefocus of dissemination activities?

Second, agroforestry is one option within a rangeof available soil improvement methods. It is expec-ted that the policies on one option (e.g., subsidy onfertilizer) will affect the demand for (and hence ad-option of) agroforestry technologies. The empiricalstudies suggest that farmers do not regard agroforestryand inorganic fertilizers as perfect substitutes of eachother. All farmers who purchased more than 50 kg offertilizers did not feel that their access to fertilizer dis-couraged them from planting trees (Peterson 1999b).This may imply that the two inputs have a synergisticor joint demand and not necessarily a competitiverelationship as would have been theoretically expec-ted. Empirical evidence for the existence of synergybetween improved fallows and inorganic fertilizers onthe same plot has been demonstrated in western Kenya(Rommelse R. pers. comm.) and in eastern Zambia(Ayuk and Mafongoya 2002).

Several explanations can be given why improvedfallow and fertilizer have a joint demand rather than acompetitive relationship. First, it appears that farmerswho are innovative and use modern practices in farm-ing will adopt fertilizer and supplement the same withagroforestry or vice versa. They simply want to useboth fertilizer and agroforestry to satisfy their quest toimprove the fertility of their soils. However, farmersrarely apply fertilizer to fields following an improvedfallow, rather they use their different soil fertility prac-tices on different parts of their field. Keil (2001) foundthat of the 66 adopters of improved fallow who usedfertilizer, only two applied fertilizer to their cropsfollowing an improved fallow (Keil 2001). Second,farmers who normally used cheap (subsidized) fer-tilizers before structural adjustment programmes findthat the new price is expensive and decide to supple-ment their nutrient needs through cheaper options (i.e.requiring less direct, cash expenses) like improvedfallows. Third, farmers who are able to afford min-

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Table 2. Summary of the broad classification of factors affecting the adoption of improvedfallows in Zambia.

A. Most frequently positively associatedwith planting of improved fallows

❑ Farmer awareness of the technology (7)

✓ Knowledge that trees can replenish soil fertility

✓ Low soil fertility is an important constraint to crop production

✓ Visual verification of the benefits of the technology

❑ Membership of farmers’ groups (4)

❑ Wealth / income status (4)

❑ Size of land holding (3)

❑ Use of modern farm inputs / desire to try new things (2)

❑ Possession of oxen (2)

❑ Cash crop production (1)

B. No direct/ambiguous relationship with farmers’ decision to establish improved fallows

❑ Gender (6)

❑ Education (3)

❑ Marital status (2)

❑ Age (2)

❑ Size of household (2)

❑ Off farm income (1)

❑ Size of maize field (1)

C. Negative relationship with farmers’ decision to establish improved fallows

❑ Labor constraints (5)

✓ Not important for testing but important for:

◦ Continuous adoption

◦ Amount of land allocated to improved fallow

❑ Short investment horizon of farmer (1)

✓ Inability to wait for two years before realizing the benefits of the technology

D. ‘Larger scale’ variables affecting farmers’ decision to plant improved fallows

❑ Location of village (is village located in pilot dissemination area?)

❑ Institutional and customary constraints (fire and free grazing of animals)

Note: The figures in parentheses indicate the number of empirical studies that specificallyidentified the associated factors

eral fertilizer presently might still continue to plantimproved fallows or practice conservation farming be-cause they are not sure that they will be able to affordfertilizer in the future, given the too frequent changesin fertilizer prices and distribution policies. Importantquestions arise: under what conditions will farmersuse a combination of the two inputs? For farmerswho are already using a combination of options, whatcombination of quantity of inputs for the different op-tions will provide economically optimum results underdifferent price scenarios?

Third, in many of the studies, adoption of agro-forestry technologies is viewed as a binary choiceproblem. In general, researchers regard a farmer ashaving ‘adopted’ a given technology if the individualhas or uses the technology. Sometimes it is a prob-lem of getting a precise definition for the word ‘ad-

option’ of agricultural technology (David 1995) andespecially in the context of agroforestry because agro-forestry adoption decisions are more complicated thanthose for annual crops (Scherr and Müller 1991). Thismay explain why some of the results of the studiesappear ambiguous. It is important to delineate farm-ers who are in ‘testing’ phase from ‘adoption’ phase(Franzel et al. 2002). This approach has been usedin adoption studies carried out elsewhere in whichresearchers asked farmers to classify themselves as‘experimenters’ or ‘adopters’ (Adesina et al. 2000).In another study, Pisanelli et al. (2003) distinguished‘experimenter’ from ‘adopter’ farmers according towhether farmers have continued to use improved fal-lows following a period of initial experimentation.Another approach that we propose in this paper isto regard adoption as a continuum where individual

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farmers are conceptualized to occupy positions alonga continuum of adoption path depending on the extentto which they have taken up various components of thetechnology. Indicators such as the size of field, dens-ity of agroforestry trees within the field, proportion offarm holding devoted to improved fallows relative tototal cropped area, number of years of agroforestrypractice and level of management attention given toagroforestry field, among others may be used to assessa farmer’s position within the continuum. Rather thanbinomial logit models (adopters vs. non-adopters),polynomial logit models or an adoption index will bemore appropriate. This will minimize the definitionalproblem regarding the exact delineation between ‘non-adopters’, ‘testers’ and ‘adopters’: presently, the lattertwo appear to be confounded together.

Fourth, some of the studies suggest that the cul-tivation of cash crops, particularly cotton (Gossypiumarboreum L.) and tobacco (Nicotiana tabacum L.) in-fluences the planting of improved fallows. There is aneed for greater insights into the nature of this relation-ship (complementary or competitive) including howcash crops and non-farm activities influence the adop-tion of improved fallows. Theoretically, opportunitiesfor off farm income can simultaneously enhance orreduce the adoption of improved fallows: if farmershave enough cash off-farm to purchase food duringinitial years of fallow, they may not need to rely on thefarms for their livelihood and this may serve as an in-centive for them to leave their field fallow irrespectiveof their land holding. On the other hand, if householdmembers engage in off farm income, the farm may beof less priority to them or the household labor avail-able to work on the farm is reduced thereby impactingnegatively on the potential to adopt agroforestry. Thistheoretical ambivalence leaves an information gap thatshould be studied in efforts to understand farmers’adoption decisions of improved fallows in locationswhere off farm opportunities exist.

Fifth, the synthesis highlighted the implication oflabor inputs and household labor supply as importantcriteria in farmers’ decision to test or continue to useimproved fallows. In eastern Zambia, poverty affectsthe effective supply of household labor, the investmenthorizons of farmers and the adoption of improvedfallows. Some poor households sell their labor byworking in other people’s fields to enable them get thestaple food, and this constrains such poor farmers fromestablishing their own improved fallow fields even ifthey wish to do so. An important question is ‘whatare the implications of this on the scaling up of agro-

forestry in different locations?’ Long-term investmenthorizons are inhibited by poverty and high discount-ing factor for future benefits that make householdsunwilling to exchange current needs for future gains.Poor farmers are less likely to have cash to purchaseinorganic fertilizers and so it would be expected thatthey would opt for soil fertility options (e.g. improvedfallows) that involve less direct cash expenses. Whatexactly is the linkage between poverty, labor availab-ility and the adoption of improved fallows? There is aneed for studies to provide empirical evidence to thequestions raised above.

Sixth, the adoption of soil fertility managementoptions cannot take place in a policy vacuum. Thestudies indicate that there exist inappropriate policiesand institutions that limit the adoption of agroforestry.It has to be noted that improved fallows is one ofthe options that farmers may use to solve soil fertil-ity problems. As a result, government fiscal policies(e.g., subsidies) and institutional support for other soilfertility management options (e.g., inorganic fertilizer)may have considerable indirect influence in shapingfarmers’ decision on agroforestry-based soil improve-ment technologies. Sanchez (1999) cited a case studyin Nigeria where short-term improved fallows wereconsidered impractical some years back because Nfertilizers were a cheaper option at that time. Theimportance of appropriate institutions and policies inthe development of agroforestry and the attainment ofsocial optimum through wider adoption of the samehas been recognized for a long period (Filius 1982).But sometimes, the objectives of private participantsin agroforestry technologies may not coincide with thesocial objectives, and so do not lead to the sociallyoptimum combination of agriculture and forestry. Forthat social optimum and widespread adoption to beattained, there is the need to identify and evaluatepolicy and institutional options that are conducive tothe adoption of the technologies. These should in-clude macro policies at the national level, and localpolicies (to reduce the constraints associated with theadoption of agroforestry) at the local level. A list ofpolicy interventions to promote the adoption of naturalresources management technologies including agro-forestry is elaborated in Izac (1997a), Izac (1997b) andPlace and Dewees (1999).

Seventh, most of the studies are based on farmerinterviews but many of them could benefit from anintegration of GIS techniques into the adoption stud-ies. Geo-referencing of survey observations has theadvantage of providing extra information that gives

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insights into farmers’ adoption decision patterns thatmay otherwise not be easily discerned in conven-tional household surveys. A recent example of suchintegration of GIS into the study of the adoption ofimproved fallow has been done in Zimbabwe (Ayukand Agumya 2001).

Conclusions and research needs

Some issues regarding definitions, methodology andanalytical approaches have emerged from the syn-thesis. These have implications for research, extensionand policy making for wider adoption of agroforestrytechnologies in Zambia and in the southern African re-gion and, should be taken into consideration in futurestudies on the adoption of improved fallows.

Adoption does not have a simple direct relationshipwith technological characteristics but it is a matrixof several hierarchies of different factors includinghousehold-specific characteristics, community-levelfactors, institutional arrangements and policies. Aquestion for further research is to evaluate the rel-ative importance of these factors to influence farm-ers’ decision. Given the multi-faceted relationship offactors, what should be the appropriate balance ofstrategies for scaling up of agroforestry technology,i.e., focusing agroforestry dissemination activities ongeographical areas that possess necessary characterist-ics that are conducive to the adoption of agroforestryor focusing individual farmers who possess the ‘right’characteristics in any community? The synthesis alsoreveals that agroforestry is one option within a rangeof available soil improvement methods. Under whatconditions will farmers use a combination of the twoinputs and, for farmers who are already using a com-bination of options, what combination of quantity ofthe two inputs will provide farmers with economicallyoptimum results under different price scenarios? Fu-ture adoption studies should integrate GIS techniquesand geo-referencing of survey observations with aview to providing additional insights into farmers’decision patterns that may otherwise not be easilydiscerned in conventional household surveys.

Further, adoption of agroforestry technologies isnot necessarily a binary choice problem but a con-tinuum of processes. Future research need to find outwhat key factors constitute the minimum set of indic-ators for measuring adoption index for agroforestrytechnology. The cultivation of cash crops – cottonand tobacco – influences the planting of improved

fallows. Is this relationship complementary or compet-itive? Under what conditions and for what typology offarmers is agroforestry and cash crop competitive andcomplementary? Do improved fallows allow farmersto reduce the area they plant to maize and allocatemore area to cash crops? Further, the synthesis indic-ates a possible linkage between poverty, labor avail-ability and the adoption of improved fallows. Whatexactly is the linkage between poverty, labor availabil-ity and the adoption of improved fallows? What are theimplications of this on the scaling up of agroforestryin different locations? Finally, the synthesis shows aclear need for conducive economic and institutionalpolicies at both national and village levels to facilitatethe adoption of agroforestry because the adoption ofsoil fertility management options cannot take place ina policy vacuum.

Acknowledgements

The authors are grateful for the financial assist-ance provided by Rockefeller Foundation, Ca-nadian International Development Agency (CIDA)and Swedish International Development CooperationAgency (Sida) during the course of preparation of thispaper. We are also grateful to two anonymous review-ers of this journal for their useful comments. The usualdisclaimer applies.

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