REVIEW Open Access

Opportunities for optimization of in-field waterharvesting to cope with changing climate insemi-arid smallholder farming areas of ZimbabweGeorge Nyamadzawo1,2*, Menas Wuta2, Justice Nyamangara3 and Douglas Gumbo2

Abstract

Climate change has resulted in increased vulnerability of smallholder farmers in marginal areas of Zimbabwe wherethere is limited capacity to adapt to changing climate. One approach that has been used to adapt to changingclimate is in-field water harvesting for improved crop yields in the semi- arid regions of Zimbabwe. This reviewanalyses the history of soil and water conservation in Zimbabwe, efforts of improving water harvesting in the postindependence era, farmer driven innovations, water harvesting technologies from other regions, and futuredirections of water harvesting in semi arid marginal areas. From this review it was observed that the blanketrecommendations that were made on the early conservation method were not suitable for marginal areas as theyresulted in increased losses of the much needed water. In the late 1960 and 70s’, soil and water conservation effortswas a victim of the political environment and this resulted in poor uptake. Most of the water harvestinginnovations which were promoted in the 1990s’ and some farmer driven innovations improved crop yields inmarginal areas but were poorly taken up by farmers because they are labour intensive as the structures should bemade annually. To address the challenges of labour shortages, the use of permanent in-field water harvestingtechnologies are an option. There is also need to identify ways for promoting water harvesting techniques thathave been proven to work and to explore farmer-led knowledge sharing platforms for scaling up proventechnologies.

Keywords: Water conservation, In-field water harvesting, Semi arid, Climate change, Adaptation, Tied contours

IntroductionClimate change has resulted in increased food insecurityin the smallholder farming sector in Africa andZimbabwe has not been spared. The most vulnerablepeople are the resource poor farmers, the elderly,women, children, and women and child-headedhouseholds because they have limited adaptive cap-acity. Marginal areas which receive low rainfall arealso vulnerable to climate change because in mostcases the rainfall is not adequate to sustain cropproduction. Semi-arid regions which receive the low-est rainfall in Zimbabwe also have the least reliabledistribution varying from 20% in the north to 45% in

the south (Department of Meterological Services 1981;Bratton 1987).Recurrent droughts have often resulted in severe crop

damage, decreased livestock production and widespreadfood shortages and the most severe impacts of droughtsare felt in countries with agro-based economies. In mostcountries with limited capacities to adapt to climatechange, recurring droughts have often led to severe foodshortages. In addition, as crop yields decline with chan-ging climate, pressure to cultivate unsuitable land willrise. This is a major challenge, as productivity from landand water in many tropical regions will decline due toland degradation (UNEP 1992).The global food challenge is huge and it will be a

challenge to feed the additional 3 billion people by 2050(Conway 1997). About 95% of this population growthwill occur in developing countries and this is a develop-mental challenge as most of their economies are

* Correspondence: gnyama@yahoo.com1Department of Environmental Sciences, Bindura University of ScienceEducation, Box 1020, Bindura, Zimbabwe2Department of Soil Science and Agricultural Engineering, University ofZimbabwe, Mount Pleasant, Box MP167, Harare, ZimbabweFull list of author information is available at the end of the article

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© 2013 Nyamadzawo et al.; licensee Springer. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.

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agricultural based. The majority, or two thirds of thepoorest people in the world are found among the 1.1billion farmers who make their living from agriculture(Rockström 2002). In Zimbabwe which is one exampleof an agro-based economy, households have been facingperennial drought related food shortages and they havebeen surviving on donor funded food aid programmes.In 2011/2012 season, the estimated number of people re-quiring food aid stood at 1.7 million (World Food Programof the UN 2012; The Zimbabwe Independent 2012; TheHerald 2012), while in 2010/2011, it was estimated that 1.4million people required food aid in Zimbabwe.Climate change models have projected a decrease in

rainfall in southern Africa (New et al. 2006), and researchhas already shown the same trends (Nyagumbo et al.2009a). Decreasing rainfall in semi arid regions impliesworsening food shortages if the current farming practicesdo not improve. Decreasing rainfall is a challenge asmost of the agricultural systems of southern Africa arepredominantly rain-fed as irrigation systems are not welldeveloped (Camberlin et al. 2009). Thus, we are facedwith huge water for food challenge, and the focus shouldbe on upgrading rain-fed smallholder farming in tropicalenvironments characterized by frequent droughts andmid-season dry spells.In addition, most of the rainfall received in semi arid

regions is lost as runoff, and very little water isharvested for plant growth or future use. In Zimbabwe,losses >50% of received rainfall have been reported(Nyamadzawo et al. 2012). High levels of runoff lossesin smallholder farming areas do not only limit wateravailability, but are also an erosion hazard and causenutrient losses (Elwell and Stocking 1988). Researchersstudying soil erosion are in agreement that parts ofZimbabwe’s smallholder areas face serious erosionproblems (e.g. Elwell and Stocking 1988; Whitlow 1988).Whitlow and Campbell (1989) reported that over 25% ofthe smallholder areas are severely eroded and this hasbeen cited as one of the major causes of poor yields.In Zimbabwe rainfall is the principal water resource

for agriculture. However, the rainfall exhibits a highdegree of inter-annual variability. Droughts of severalyears duration, such as that which occurred from 1981 to1984 have been recorded in southern Africa (Tyson 1986)and from 1959 to 2002; Zimbabwe experienced 15droughts occurring on average, every 2 to 3 years(World Bank 2009). In some semi-arid smallholderfarming regions the rainfall patterns and distribution havechanged and there has been an increase in the averageduration of intra-seasonal dry spells (New et al. 2006).All this has resulted in perennial food shortages due toinsufficient rainfall which causes poor yields. It isbecoming increasingly clear that to face the foodchallenge over the coming 50 years, combined efforts

of developing climate smart rainfed and irrigated agri-culture will be required (Rockström 2002). However,irrigation is too costly make an impact on rural households’food security for the near future. To reduce the vulnerabil-ity to smallholder farmers in semi-arid regions to climatechange and variability, and to increase the resilience toclimate change there is need to optimize in-field waterharvesting techniques so as to improve crop yields. It istherefore imperative to investigate the options to increasewater productivity in rain-fed agriculture for increased foodproduction. With improved in-field water harvesting,harvested rainfall can possibly sustain crop productionduring the mid-season dry spells and this will reducecrop failures and may ultimately lead to improvedhousehold food security.In-situ rain water harvesting, involves the use of

methods that increase the amount of water stored in thesoil profile by trapping or holding the rain where it falls,and it involves small movements of rainwater as surfacerunoff, in order to concentrate the water where it isrequired (UNEP 1997). Water harvesting retainsmoisture in-situ, through structures that reduce runofffrom fields and hold water long enough to allow it toinfiltrate. Improved in-field water harvesting canincrease the time required for crop moisture stress to setin and thus can result in improved crop yields. Improvedwater harvesting may result in improved crop yields,food security and livelihood among households. Waterharvesting is nothing new but a revival of old techniquesthat have received little attention since the modernisa-tion of agriculture in the 1940s (Rockström 2002). Waterharvesting is believed to have originated from Iraq over5000 years ago, where methods such as such as diversionof “Wadi” flow onto agricultural fields were used(Hardan 1975; Hatibu and Mahoo 1999). This reviewwill therefore evaluate current in-field water harvestingpractices in the smallholder farming areas located in thesemi-arid regions of Zimbabwe and other options thatcan be used for optimising in-field water harvesting toimprove the resilience against changing climate.Zimbabwe is located in southern Africa between 19°

and 30° south of the Equator. The country has a totalland area of 39 million ha and approximately 21 million ha(54% of the land area) is used for agricultural production.Vincent and Thomas (1961) partitioned the country intofive agro-ecological or Natural Regions (NRs), basedmainly on the mean annual rainfall (mm year-1) which isreceived between November and April (Table 1). Mostcropping is done in NRs I and II (21% of land area), whileNRs IV (33%) and V (28%) are considered too risky forcrop production. More than one and a half million farminghouseholds in the smallholder settlements farm are locatedon about 49% of the country’s agricultural land, of which>70% is in marginal NRs IV and V. Most of the smallholder

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farming areas are in the marginal agro-ecological regionswhich have (i) low rainfall (ii) severe dry spells; and (iii)shallow sandy soils of low fertility (FAO 2006). The data oncurrent water harvesting and conservation practices thathave been used and that are currently being promotedwere collected from literature that included publishedand unpublished materials from Government departmentsin the Ministry of Agriculture such as the Institute ofAgricultural Engineering and Agricultural extension ser-vices (Agritex), the World Wide Web, non-governmentalorganization (NGO) and research reports.

Results and discussionPre-independence soil and water conservation in ZimbabweSoil and water conservation in Zimbabwe (formerlyRhodesia) dates back to the early 19000s following theintroduction of the plough and permanent settlements.The plough was introduced around 19200s following thearrival of white settlers. The introduction of permanentsettlements and the plough also saw the abandonment oftraditional farming practices which were used to conservewater in-field. The introduction of the plough was accom-panied by massive land degradation and this led to theintroduction of the contour ridge that was designed byAlvord in the 19300s (Alvord 1958) and some conservationagriculture practices in the form of Conservation Farmingbasins that were first implemented in Musana communallands in the North-eastern part of the country by BrianOldrieve (Oldrieve 1993).The contour ridge was mainly targeted for the

commercial farming sector in high rainfall areas.However, due to increased land degradation in the newlyestablished smallholder farming areas, contour ridges werealso introduced indiscriminately to combat accelerated soilerosion in smallholder farming areas in the 1930s, and laterenforced through the Natural Resources Act section 52 in1941, without considering the rainfall characteristics thathad contributed to accelerated erosion after the introduc-tion of the plough in the 1930s (Aylen 1941; Alvord 1958).In semi arid areas contour ridges were inappropriate asthey disposed off the precious water from the fields instead

of retaining it. Construction of standardized contour ridgeshas been enforced by governments since the 19300s anddue to the enforcement; the whole idea of soil conservationbecame unpopular among smallholder farmers. The use ofcontour ridges was resisted by farmers, as it was seen as atool of oppression because of the brute force used toenforce the law and the high labour demand required forthe construction of the contours. Contour ridges took off15% of the land out of production and there was noappropriate equipment to use. They were also irrelevantto drought prone regions where rainfall is scarce. Duringthe liberation war of the 19700s the concept of “FreedomFarming” was introduced by the freedom fighters and thisinvolved destruction of existing contour ridges as a protestagainst the colonial regime and this only stopped afterindependence in 1980. However, to date, the standardcontour ridges are to some extent still enforced, but it isnow possible to establish other means of soil conservationwithout actually breaking the law (Dreyer 1997).

Soil and water conservation efforts of the 1980 and19900s in ZimbabweIn 1980, when Zimbabwe became an independent state, thegovernment formulated new policies for the agriculturalsector. However, most of these policies failed becausethe authorities employed a top-down policy, with thegovernment and the secretariat assuming the custodialrole (especially regarding the resource-poor farmers).Even today, although perception and approaches arechanging, the standard contour ridges are to some extentstill predominant, despite the introduction of other prac-tices in soil and water conservation (Gumbo et al. 2012).The uses of water harvesting technologies for improvedwater use efficiency have been evaluated in several semiarid regions of the country. Farmers in semi arid regions ofChivi have successfully used water harvesting technologiessuch as the Fanya ju and spreading of termitaria (Hagmannand Murwira 1996a) to increase crop yields relative toconventional tillage. In addition, farmers driven innovativesoil and water harvesting practices e.g. Infiltration pits(chibatamvura), crop rotations, winter cropping, improved

Table 1 Natural regions, a real coverage (hectares (ha)) and rainfall distribution in Zimbabwe

Natural region Area (000 ha) % of total land Annual rainfall (mm) Farming system

I 613 1.56 >1000 Suitable for dairy farming forestry, tea, coffee, fruit, beefand maize production

II 7 343 18.68 750-1000 Suitable for intensive farming, based on maize, tobacco,cotton and livestock

III 6 855 17.43 650-800 Semi-intensive farming region. Suitable for livestockproduction, fodder crops and cash crops

IV 13 010 036 33.02 450-650 Suitable for farm systems based on livestock and resistantfodder crops. Forestry, wildlife/tourism

V 10 288 26.2 <450 Extensive farming region. Suitable for extensive cattleRanching, forestry, wildlife/tourism

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tillage techniques and many others have been used inZimbabwe. A survey by Mutekwa et al. (2005;2006) in ward(Ngundu) of Chivi district in Masvingo with a total popula-tion of 9031, showed that infiltration pits, fanya juus, tiedridges, macro-catchments and graded contours wereadopted by 61%, 34%, 27%, 10% and 7% of the populationrespectively.In the first 20 years after independence efforts to

manage water in rain-fed systems using water conserva-tion technologies focused on in-situ water harvestingtechniques such as tied ridging (mariji), tied furrows andconservation tillage (CONTIL) (Hagmann and Murwira1996b). The CONTIL project began in Zimbabwe in 1988to 1996 as a collaborative project between AGRITEX andGTZ implemented with the aim of developing a numberof tillage techniques to address problems related to soilloss, water run-off, and declining yields (Vogel 1992). Itsinitial aim was to reduce soil erosion through improvedfarmer husbandry techniques and it evaluated three re-duced tillage systems (mulch ripping, clean ripping, andtied ridging) against two traditional systems (conventionaltillage and hand hoe) (Marongwe et al. 2012). The projectevolved in an attempt to promote a completely differentway of working within the government extension service.This implied a shift away from Agritex’s rigid, linear, topdown extension model, to a more process-orientedapproach where farmer driven needs led to the develop-ment of the bottom up approach (Hagmann and Murwira1996b). After five seasons of research, Moyo and Hagmann(1994) concluded that mulch ripping with its higher water-use efficiency appeared to be the most viable conservationtillage treatment in the semi-arid areas of Zimbabwe. How-ever, several on-station and on-farm research activitieson conservation tillage and erosion by the Institute ofAgricultural Engineering (IAE), Agricultural ResearchTrust Farm (ART Farm) and Henderson Research Stationfailed to see any significant uptake of conservation tillagetechnologies by the smallholder farming sector inZimbabwe (Marongwe et al. 2012).Nyagumbo (1999) describes experiences on maize

production using tillage systems from on-station andon-farm research in Zimbabwe carried out between1988 and 1997. On-station, four conservation tillagemethods namely no-till tied ridging, mulch ripping,clean ripping and hand hoeing were compared to thecontrol of conventional tillage system and the resultsshowed that on farm maize yields were significantlydifferent from farmer to farmer, depending on theirmanagement skills, seasonal rainfall and soil type. Theresults from the work by Nyagumbo (1999) showed thatthere was no scope for giving blanket recommendationsto farmers on no-till tied ridging. It was also realisedfrom the study that tied ridging alone could not bringbetter yield results to the farmers; hence there is a

need to incorporate soil fertility and other managementcomponents for improved productivity. Tied ridgescould not work without the support of structures suchas contour ridges, infiltration pits and other preventivestructures. Tied ridges on sandy soils did not overallyincrease soil water content within the root zone due tothe low water holding capacity of sands.Despite the effectiveness of some water conservation

techniques, adoption by farmers has been poor mainlybecause of several factors among them; high labourintensity, e.g. in Tanzania, the cost of making tie ridges isestimated at 33% higher than conventional land prepar-ation using hand hoes (Ibraimo and Munguambe 2007).(ii) Available water harvesting techniques have beendesigned in a “one size fits all” approach as there are notechnical guidelines on water harvesting technologies suit-able for different climatic and soil conditions. To addressthese challenges, there is a need of a more efficient captureand use of the scarce water resources in arid and semi-aridareas. An optimization of the rainfall management, throughwater harvesting in sustainable and integrated productionsystems can result in improved livelihood of the small-scalefarmers’ through improved rain fed agriculture production(Ibraimo and Munguambe 2007).In 2003, after substantial donor funding targeting

improved food security for vulnerable households, therewas renewed effort to promote soil and water conservation.Some of the technologies that were promoted includedminimum mechanical soil disturbance, maintenance of soilcover with organic materials and diversifying crop rotationsor sequencing or associations adapted to local environ-ments (Marongwe et al. 2012). In 2008 the government gotinvolved in conservation agriculture resulting in the launchof the Conservation Agriculture Promotion Network(CAPNET) which brought together different governmentdepartments and ministries (Ministry of Agriculture,Mechanization and Irrigation Development 2008) but todate, CAPNET has since been absorbed into the mainCA Task Force.In addition some permanent water conservation practices

that were intiated in the 1980s’ such as the zero-grade ordead level contours reinforced with infiltration pits werealso promoted by non-governmental organizations (NGOs)in semi arid areas of areas such as Gwanda, Zvishavane andChiredzi districts during this re-newed effort (Motsi et al.2004; Mugabe 2004; Munamati and Nyagumbo 2010;Mupangwa et al. 2011; Gumbo et al. 2012). Results fromthese studies have shown that dead level contours andinfiltration pits can contribute towards improved soilwater status in the cropped fields, as soil water on bothupslope and downslope sides of the infiltration pit wasreplenished (Mugabe, 2004).Dead level contours are permanent and they are only

made once and they have been reported to increase

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maize yields in semi arid regions of Zimbabwe (Gumboet al. 2012). However, though considerable progress hasbeen made with respect to adoption of dead level contoursby farmers (Hagmann and Murwira 1996a), little is knownabout the technical design of these water harvestingtechniques for different soils and rainfall regimes. Some ofthese water harvesting technologies may cause a potentialrisk of erosion if the quantities of runoff harvested isgreater than the capacity of the structures. However, onlya few studies e.g. Mupangwa et al. (2006) and Gumboet al. (2012) have been carried out to assess this.

Water conservation lessons from other regionsThere are several in-field water conservation practicesthat have been used in several regions of Africa including:earth bunds, planting pits or planting basins and theirmodifications used in different parts of East and WestAfrica (Critchley 2009). Planting pit or basin is commonlyused in the sub-region with various modifications includingthe zai pits (Tassa) in Burkina Faso, Niger and in Mali, andhalf moon (demi-lunes) in Niger. The zai pits for concen-tration of in-field runoff, which originating in Burkina Fasohave been practiced for centuries among smallholderfarmers in West Africa (Reij et al. 1988). In a study in Niger,Olaleye et al. (2006) reported higher yields on zai treat-ments compared to flat planting and this was attributed toa build-up in the soil organic matter contents which mayhave increased the soil water holding capacity in the zaitreatments. In Kenya, the zai technique utilizes shallow,wide pits that are about 30 cm in diameter and 15–20 cmin depth, in which four to eight seeds of a cereal crop areplanted. In the Njombe district of southern Tanzania, thepits are made bigger and deeper (at least 0.6 m deep), and a20 liter volume of manure is added and farmers plant about15 to 20 seeds of maize per pit (Mati 2005).Another variant of the zai is the Chololo pits, a method

in which pits with a diameter of 22 cm and a depth of30 cm are used. The pits run parallel to the contour andhave an in-row space of 60 and inter-row spacing of 90 cm.Ashes (to expel termites), farmyard manure and cropresidues are added into the pit and this is covered by a littlesoil, and some space is left to hold runoff water. Some ofthe soil that was excavated when making the pit is used tomake a small bund around the hole. One or two seeds ofmaize or millet or sorghum are planted per hole and yieldshave been reported to triple even during very dry years(Mati 2005). A larger version of the zai is the ‘five by nine’pit, which has surface dimensions of 60 x 60 and a depth of60 cm. The pits are larger than zai and “five by nine” refersto the five maize seeds (for dry areas) or nine maize seeds(for wet areas) planted at the pit diagonals. This type of pitcan be re-used for a period of up to 2 years (Mati 2005).Micro basins, also called earth basins have also been

used in semi-arid regions of Africa to capture and hold

rainwater (Kassougue et al. 1996). Micro basins areconstructed by making low earth ridges on all sides, theyare normally circular, and square or diamond shapedmicro-catchments which are 1-2 m in width and about0.5 m depth (Mati 2005). In addition, earthen bunds whichare of various forms of earth-shapings created for pondingrunoff water have been used for water harvesting in semiarid regions of Africa (Ibraimo and Munguambe 2007).The variations of earthen bunds include contour bunds,semi-circular bunds and Negarims microcatchments whichhave been used in arid and semi-arid regions where theseasonal rainfall can be as low as 150 mm (Mati 2005).These earthen bunds have been used widely in Kenya, forexample in Busia, district of Kenya, while semi-circularbunds are made by digging out holes along the contours.Negarims microcatchments are regular square earth bunds,which have been turned 45 degrees from the contour toconcentrate surface runoff at the lowest corner of thesquare where there is an infiltration pit dug. Fruit trees canbe grown in the pits were all the runoff is concentrated.Contour earth ridges, which are generally 15–20 cm

high, constructed parallel to the contour and spaced 1.5to 3 m apart, have been found to be useful for producingcrops and trees. Contour earth ridges are constructed bydigging a furrow along the contour and throwing the soilon the downslope side to form ridges. However, theiradoption in Kenya has been limited without technicalassistance (Thomas 1997). Broadbed furrow systems area modification of contour ridges, with a catchmentahead of the furrow and a within-field micro catchmentwater harvesting systems which are used extensively inEthiopia, Kenya and Tanzania. The systems are madefrom small earthen banks with furrows which collectrunoff from the catchment area on the higher sidesbetween the ridges. The system is most suitable in areaswhere the annual rainfall is from 350 mm-700 mm, witheven topography, with gentle slopes of about 0.5-3%steepness and soils that are fairly light and have highinfiltration rates (Mati 2005). The other water harvestingtechnologies that have also been successfully used in othercountries include the half moon basins in Mali and the lowlying crescents in Sudan (El Sammani and Dabloub 1996).Several recommendations on the different water

harvesting technologies have been made from the regionsand Zimbabwe can certainly learn from those experiences.For example, in Arusha and Kilimanjaro regions ofTanzania, an evaluation of tied ridges, open ridges,potholes (small holes) and flat planting as techniques forwater harvesting showed significant maize yield increasesunder tie ridging as this method retained more moisturethan the other methods. The recommendations were thattied ridges were not suitable where the average annualrainfall is more than 800 mm, as they may cause waterlogging. In areas with sandy soils, tie ridging is not

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recommended due to high water percolation and waterlogging respectively, while in drier areas with about500 mm rainfall, tie ridging is recommended to farmerswho have easy access to capital resources, while potholingis recommended to farmers with scarce resources. Otherrecommendations included the crest and side seed place-ment in ridges to eliminate water logging. However, themain problems associated with these water harvestingstructures are that they are difficult to construct, havehigh labour requirements and they do not allow the use ofmechanization (Critchley and Siegert 1991). Some of thewater harvesting technologies needed to be constructedon an annual basis and this was a reason for poor uptake.From these experiences from the region, it was observedthat water harvesting technologies should not be given asa blanket recommendation.

Future directions of water conservationBesides the water harvesting technologies that have beenpromoted in the 19900s, currently some interventionsthat have been borrowed from other regions of subSahara Africa are being promoted or tested in Zimbabweand these include; basin tillage (makomba), a modificationof the zai which has been widely promoted under PrecisionConservation Agriculture (PCA), half moon basins andshallow planting furrows using a hand hoe among others(Twomlow et al. 2008). These basins were introducedtargeting poor and vulnerable households without accessto draft power and also during a period when initiativeswere promoted by NGOs without the assistance ofthe government extension system which was largelyexcluded by the donors. It was only until 2008 that thegovernment got involved in conservation agriculturewhen they launched the Conservation Agriculture Promo-tion Network (CAPNET) which has since been absorbedinto the national CA Task Force.In Zimbabwe by the 2007/2008 season, more than 50

000 households had tried the PCA technology and itresulted in increased average cereal yields by 50 to 200%in > 40 000 households (Twomlow et al. 2008). For mostof these households, inputs were provided, however, thereis need for planning to assure success and sustainability,so that the farmers are able to support themselves withoutthe help of NGOs by the end of the programs. Most of theprograms have failed to continue after the NGOs or theGovernment stopped providing inputs. From the availableliterature, the major challenges of all the technologies stillremain high labour intensity and at times blanket recom-mendations of interventions and resource constraint offarmers (Munamati and Nyagumbo 2010). For instancemakomba though they have been adopted by somefarmers are still a challenge because of the perennial highlabour demand, to the extent that they have been given anickname, “diga ufe” in vernacular large which translate to

“dig and die”. To date farmers who are willing to adoptsuch technologies face a lot of stigma from fellow farmersbecause such technologies are perceived to be for the poorand not for the resource endowed. Resource ownership isalso a key factor in farmers’ ability to scale out waterharvesting technologies and a study by Munamati andNyagumbo (2010) showed that performance was signifi-cantly linked to resource status.In the face of these challenges, farmers in semi-arid

areas have tended to show more interest in large, semipermanent to permanent water harvesting mechanicalstructures (Hagmann and Murwira 1996a). In recent years,increased attention has been focused on introducing otheroptions for water harvesting as alternatives to the availabletechnologies. These options include modifications of thestandard contour ridges through incorporating infiltrationpits (Maseko 1995), deepened contours, fanya juus, tiedfurrows, the ‘five by nine’ method that is used in Kenya(Mati 2005) and dead level contours (Motsi et al. 2004;Gumbo et al. 2012).The dead level contour is a farmer driven innovation

developed in 1988, which led to the adjustments andmodification of the standard graded contours. In 1988,about 10 farmer innovators in Zvishavane and Chividistricts, in Zimbabwe, were part of the Indigenous Soiland Water Conservation in Africa Project to share theirknowledge and discuss dead level contour innovations(Hagmann and Murwira 1996a). After that, the technologyof dead level contours has spread, and the number ofadopters increased to about 5000 in ten pilot districts.However, research has not moved fast enough to scientific-ally justify the use of these techniques such that little isknown about the conditions under which such techniquesprovide beneficial effects (Nyagumbo et al. 2009b). Somework by NGOs such as Practical Action, have shown thatfarmers benefit a lot from using dead level contours(Nyagumbo et al. 2009b; Munamati and Nyagumbo 2010;Mupangwa et al. 2011; Gumbo et al. 2012), such that about40% of the farmers still use these water harvesting strategiesalthough the project that promoted them ended in 2004.Another water harvesting technology that needs evalu-

ation is the tied contour. To date there are no studiesthat have evaluated the potential benefits of using thetied contour ridges for water harvesting in semi aridsmallholder farming areas of Zimbabwe. The advantageof tied contours is that they are a modification of thestandard contour ridges which are already in place inalmost every field in the smallholder farming areas.Permanent water harvesting technologies like tiedcontours are likely to be well received by farmers andfuture programmes should promote such technologies inaddition to current efforts, especially in semi-arid areas.However, the merits of using these technologies are stillunknown and this calls for further research to evaluate

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the performance of tied contours as a water harvestingtechnology for the semi-arid smallholder farming areas.Experiences from earlier large scale adoption of soil and

water management techniques, for example the wideadoption of soil and water conservation in Machakosdistrict in Kenya (Mati 2005), showed that improved man-agement of soil and water also reduces land degradation.Therefore the adoption of a variety of water conservationtechnologies which should be availed to farmers in the‘farmers basket of innovations’ may also control surfacerunoff and erosion, which currently constitutes the largestsource of land degradation in tropical savannahs. There isneed to couple soil conservation with other practices withshort-term benefits. Research shows smallholder farmerswill adopt technologies with short term benefits even iflong term benefits are higher.

Research gapsMost of the water that is harvested in-field is stored inthe soil. In situ water harvesting works better where thesoil is deep enough and the water holding capacity islarge enough to retain moisture which can be used bythe crop during dry spells and where rainfall is equal ormore than the crop water requirement. Some of thesetechnologies may not work in areas were the soils aresandy, because of poor water retention. Currently therecommendations for water harvesting technologies giveblanket recommendation and do not consider inherentdifferences in soil water holding capacities, soil depthand texture. Thus, there is need to carry out research onwater harvesting across a range of soils so as to recommendthe best technology for each soil type. In addition, there isneed to integrate water harvesting with improved fertilityand crop management in order to increase efficiency of useof the harvested water.In addition, the effects of combining more than one

in-situ water harvesting technology on crop growth arealso unknown and this calls for further research. Thereis also need to identify sustainable mechanisms forpromoting evaluated and proven water harvestingtechniques as current extension methodologies and donordriven initiatives in Zimbabwe have failed to increaseuptake and sustained adoption of such techniques.Exploring farmer-led knowledge sharing platforms shouldbe explored for scaling up proven technologies.There is need for policies to promote the uptake of

in-field water harvesting in semi arid to arid regions ofZimbabwe. Zimbabwe like many other countries in theregion has no clear government policies and legislationon the use of in-field water harvesting in semi arid to aridregions (Nyagumbo and Rurinda 2011). The smallholderfarmers remain at the “tail-end” of policy making, and inmost cases, policies are designed using the top to bottomapproach. In addition, there are no incentives that are

given to farmers who take up innovative in-field waterharvesting. For some farmers the benefits are there butresearch must clearly show the benefits of adopting im-proved water harvesting, among them increased yield andimproved food security. There are no technical guidelinesor manuals that farmers can use as reference material formost water harvesting technologies. In the few caseswhere the guidelines are available, they are mostly inEnglish and not in a language most farmers would easilyunderstand (Practical Action 2012). Except for the effortby some NGOs, the government has not been activein providing manuals even to its extension staff andthe farmers. In addition, the land tenure system inZimbabwes’ newly established resettlement areas is notwell defined. After the fast track land reform that began in2000, land users in new resettlement areas are not willingto invest in water harvesting technologies, because theylack land tenure security, even though they have theknowledge of the technologies.There is also need to evaluate promising water conserva-

tion strategies from other regions before promoting themin smallholder farming areas in Zimbabwe. A technologymay be indigenous to the farming system of origin, whilebeing an innovation to the society of adaptation. Sometechnologies that have been evaluated in semi aridcountries e.g. Kenya and Sudan should be evaluated forsuitability to local conditions.

Conclusions and recommendationsIn-field water harvesting is one of the many climatechange adaptation strategies that can be adopted byfarmers in the semi- arid regions of Zimbabwe. In-fieldwater harvesting can potentially enhance soil waterstorage, and this will enable crops to survive during midseason droughts. Improved water harvesting may resultin improved crop yields, food security and livelihoodamong households. Water harvesting should be inte-grated with other management strategies e.g., improvingsoil fertility management, tillage, timing of operations,pest management and choice of cropping system inorder to increase the efficiency of use of the harvestedwater. Water, is probably the strategic entry point, forreducing risk of crop failure due to water scarcity.However, there is need for changes in policies topromote the use of in-field water harvesting technologyin the semi-arid smallholder farming areas, improvedextension activities, knowledge dissemination, and thepromotion of farmer-led knowledge sharing to increasethe resilience of farmers to changing climate. Thepolicies should also address the current land ownershipstructure to encourage farmers to invest on their land.Water harvesting technologies from other regions alsoneed to be explored and tested in Zimbabwe. Morepermanent water harvesting technologies may be a solution

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to the problems of perennial high labour requirements ofthe current water harvesting practices; hence there is needto promote them. Farmers should be given a ‘farmersbasket of innovations’ that is full of options, from whichthey could select the ones most suited to their complexand diverse agronomic, environmental, climatic, socio-economic conditions and resource endowments.

Competing interestThe authors declare that they have no competing interests.

Authors’ contributionsGN generated the draft paper outline and the first draft, DG contributed asection on uptake of water harvesting technologies, MW and JN revised andcommended on the draft before submission. All authors contributed onreferences, read and approved the final manuscript.

Author details1Department of Environmental Sciences, Bindura University of ScienceEducation, Box 1020, Bindura, Zimbabwe. 2Department of Soil Science andAgricultural Engineering, University of Zimbabwe, Mount Pleasant, BoxMP167, Harare, Zimbabwe. 3ICRISAT Bulawayo, Box 776, Bulawayo,Zimbabwe.

Received: 5 October 2012 Accepted: 5 March 2013Published: 11 March 2013

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doi:10.1186/2193-1801-2-100Cite this article as: Nyamadzawo et al.: Opportunities for optimization ofin-field water harvesting to cope with changing climate in semi-aridsmallholder farming areas of Zimbabwe. SpringerPlus 2013 2:100.

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