SECTION 1 Factors constraining the potato subsector · Factors constraining the potato subsector In the years ahead, world potato production is expected to grow at a rate of 2.5 per

SECTION 1

Factorsconstrainingthe potatosubsector In the years ahead, world potatoproduction is expected to growat a rate of 2.5 per cent a year,presenting opportunities for expandedutilization and opening up newmarket segments. To realize the fullpotential of this crop, developingcountries must address both supply-and demand-side constraints.

POTATO MARKETIN KASUNGU, MALAWI.

(PHOTO: ANNE LI)

The potato’s biologicalcharacteristicsMany constraints derive from the biologicalcharacteristics of the potato itself. Theseinclude the low multiplication rates of seedtubers, and the technical difficulties andcosts associated with maintaining seedquality through successive multiplications,owing to the potato’s susceptibility to soiland seed-borne insect pests and diseases.Seed tubers are also bulky: two to threetonnes per hectare is the typical seedrequirement. Stringent phytosanitaryrestrictions limit the movement of potatogermplasm, seed tubers and fresh warepotatoes. Potatoes have high fertilizerrequirements but low utilization efficiency.Post-harvest, fresh potato tubers deterioratequickly in tropical and subtropicalenvironments, especially in the lowlands.

Lack of efficient seed systemsMany developing countries lack efficientsystems for the regular multiplication anddistribution of certified seed tubers and therapid deployment of new, improved varieties.Causal factors include the limited technicalcapacity of human resources, lack ofmanagerial expertise and inadequateresource allocations to seed systems and thepotato subsector in general. As a result,farmer-based seed systems are still common,and have managed to supply plantingmaterial of limited quality over the years,and contributed to expanding cultivation ofthe crop. Farmer seed systems face manychallenges, but also offer an opportunity to

improve seed supply, provided suitabletraining is available and links with theformal sector are established.

Diseases and insect pestsDiseases and insect pests are another majorconstraint. New strains of late blight havereached many developing countries andcontinue to spread. Late blight constitutesthe most serious threat to increased potatoproduction. Second to late blight inimportance, particularly in warmer, moretropical regions, is bacterial wilt. The impactof insect pests varies between regions. Majorinsect pests include aphids, tuber moths, leafminers, Colorado potato beetle and Andeanpotato weevil.

13FACTORSCONSTRAININGTHE POTATOSUBSECTOR

Technical factors

14SUSTAINABLEPOTATOPRODUCTION

The US government’s AfricanGrowth and Opportunity Act(AGOA) provides preferentialaccess for more than 1,800 tariff

lines, including agriculturalcommodities, from designatedsub-Saharan African countries.The Everything But Arms (EBA)

initiative of the European Union(EU) eliminates import tariffsand restrictions on numerousgoods, including agriculturalproducts, from least developedcountries provided that planthealth regulations are met. EBAgrants duty-free access forimports from most LessDeveloped Countries, except fora few sensitive commodities(e.g. bananas, sugar and rice)that will be liberalized gradually.Most of the commoditiesincluded in EBA previouslyreceived duty-free access to theEU under preferentialprogrammes such as theLomé/Cotonou Agreement.

Export markets open in USA and Europe

LOCAL TRANSPORTATIONOF POTATOES TO MARKETIN MYANMAR.(PHOTO: ZIN MIN)

High production costsand lack of creditCompared to other food crops, production ofpotatoes is capital-intensive, requiring thepurchase of large quantities of bulky seedand the application of high-cost inputs suchas fertilizers and pesticides. With limitedaccess to credit and few means of mitigatingthe risks of taking out loans, small-scalefarmers find it difficult to compete in potatoproduction. The current global financialcrisis could leave a great number of farmerswith little money and no credit to invest inproduction.

Price instabilityWith potato becoming increasingly a cashcrop, small-scale potato growers arevulnerable to abrupt changes in input andoutput prices. Seasonal and year-to-yearprice movements can affect individual smallgrowers who lack the financial resourcesand resilience of larger producers andcooperatives.

Inefficiency of local marketsPotato prices are usually determined bysupply and demand, not the vagaries ofinternational markets as in the case ofcereals. It is, therefore, a crop that can helplow-income farmers and consumers to rideout episodes of food price inflation, such asthat experienced worldwide in 2007-08.However, the profitability of potato dependson efficient local markets and measures tocontrol overproduction.

Limited access to higher valuemarketsTo be successful, small-scale potato growersneed access to profitable emerging domesticmarkets – such as the rapidly growingprocessing segment – as well as to potatoexport markets. However, access to domesticmarkets is often restricted by the marketingpower of foreign suppliers, while exports areconstrained by trade barriers in developedcountries to processed products from thedeveloping world. However, there areencouraging “success stories” that illustratehow small-scale producers can increaseproduction and expand their market share.In India, potato growers who adapted newtechnology with the support of McCainFoods Ltd more than doubled their yieldsand incomes. Other private industries,including small businesses, have launchedpotato chips made from coloured nativepotatoes that were prototyped by CIP inorder to promote the sustainable use ofbiodiversity in the Andean Region. Recentlegislation in the USA and Europe providegreater access to agricultural products fromthe developing world.


Socio-economic factors


Neglect of the potato subsectorWith a few notable exceptions – such asEthiopia – most developing countries havepolicies toward the potato subsector, andespecially small-scale producers, that can bebest characterized as “benign neglect”. Littleor no public investment is targeted atintegrated strategies for crop improvement,value addition and marketing schemes orthe potato production-processing-marketingchain. Many countries lack adequate seedproduction systems backed by certificationand seed laws. Breeding rights are often notrespected, reducing incentives to breeders tocreate new adapted and resistant varieties. Inmany areas, poor infrastructural facilitiesand poor access to markets are also majorchallenges to expansion of potato productionand its profitability.

Inadequate capacity buildinginitiativesThe potato has attracted private sectorinvestment in the crucial area of seedmultiplication and seed systems in only afew countries. Support for programmes forthe diffusion of new varieties and for thescaling up of existing integrated disease andinsect pest management technologies andmethodologies is generally inadequate.Programmes to upgrade the skills of potatogrowers need to be matched by governmentefforts to create, monitor and enforceregulations on pesticide use and the spreadof pesticide or fertilizer residues into watersupplies, which are major constraints to thesustainability of potato production systems.

Lack of support to farmerorganizationsand entrepreneurs Support for potato farmer groups andassociations and for local entrepreneurshipis lacking in many countries. In Bangladeshand Pakistan, powerful lobbies represent themost serious obstacle to the development ofa local seed potato industry. One notableexception is Argentina, where efforts arebeing made by public and private sector toimprove seed quality and promote varietydevelopment, and to transfer technology forintegrated crop management to its contractgrowers.


Policy and institutional factors

SECTION 2

Good AgriculturalPractices andpotato productionThe term Good Agricultural Practices(GAPs) refers to principles and codesof practice that are applied to on-farmproduction and post-production processesand aim at ensuring safe and healthyfood and non-food agricultural products,while taking into account economical,social and environmental sustainability.


With most GAP applications,production costs are lower,losses reduced, and use of inputsrationalized as a bettermanagement system is put inplace. The cost of private GAPstandard certification (e.g. forGlobalGAP or Tesco Nature’sChoice) may be higher owing tostricter requirements. However,this does not necessarily have tobe the case with adoption ofgood practices per se. Generally,there is no higher cost to theconsumer – that is why retailersand commercial farming arerapidly adopting GAPs. Whereadoption of GAPs entailsadditional costs, the benefits ineconomic, social orenvironmental terms are usuallyhigher.

The cost of GAPs

SORTING OF POTATO IN INDIA.(PHOTO: RINI MAJUMDAR)

GAPs may be applied to a wide rangeof farming systems and at differentscales. They are applied throughsustainable agricultural methods,

such as integrated pest management,integrated water and fertilizer management,and conservation agriculture. GAPs arebased on four principles:1. to economically and efficiently produce

sufficient quantities of safe andnutritious food;

2. to sustain and enhance ;3. to maintain viable farming enterprises

and contribute to livelihoods;4. to meet the cultural and social needs of

society.

GAP applications are being developed bygovernments, NGOs and the private sector tomeet the needs of growers and processorsand for other specific purposes. They providethe opportunity to assess and decide onwhich to follow at each step of theproduction process.

It is important that GAPs are appliedin a coordinated way. For each agriculturalproduction system, GAPs should be part ofa comprehensive management strategy,providing for adjustments when needed inresponse to changing conditions. Theimplementation of such a managementstrategy requires knowledge, planning,measuring, monitoring and record-keepingat each step of the production process.Adoption of GAPs may sometimes result inhigher production, processing andmarketing costs, and higher prices for the

consumer. To minimize costs, whilemaintaining the quality and safety of foodproducts, participatory technical trainingand advice can be used to inform farmers ofnew technologies that will benefit them.

Information on options for GAP adoptionwould be facilitated through the use ofcommon databases and informationexchange platforms on available enablingtechnologies and integrated productiontechniques for different major agro-ecological areas.

21GOODAGRICULTURALPRATICESAND POTATOPRODUCTION

GAP concepts and principles


Soil management6 Reduce wind and water erosion through

hedging and ditching. 6 Apply fertilizers at appropriate moments in

adequate doses (e.g. based on soil analysis andcrop requirement) to avoid extra costs andpossible run-off and leaching.

6 Maintain or restore soil organic contentthrough application of manure, use of grazingand/or crop rotation .

6 Reduce soil compaction by avoiding use ofheavy machinery.

6 Maintain soil structure by limiting heavy andsometimes unnecessary tillage practices, andthrough use of cover crops such as pulses.

Water use efficiency6 Use minimum or zero-tillage and maintain soil

cover to reduce soil evaporation and improvesoil structure and water infiltration.

6 To avoid water loss by drainage, scheduleirrigation and monitor plant needs and soilwater reserve status.

6 Prevent soil salinization by matching waterinput to needs, allowing some drainage andrecycling water whenever possible.

6 Avoid excessive drainage and fertilizer run-off. 6 Maintain permanent soil cover in winter to

avoid nitrogen run-off and wind erosion thatcontributes to soil degradation.

6 Carefully manage the water table by limitingwithdrawals.

6 Avoid soil compaction (e.g., caused by toomany passes of farm machinery) which cancause water logging and lead to emergence ofpotato diseases during storage.

Examples of GAPs

Applied to the potato subsector,GAP principles imply that potatoproduction:

1. takes place in an economically efficientway;

2. contributes to food security by providingquantity and nutritional quality for abalanced food supply;

3. along with post-harvest handling andprocessing, ensures a safe food supply toconsumers;

4. conserves the natural resource base;

5. does not lead to emissions that endangerthe environment and biodiversity;

6. enhances potato biodiversity and ensuresa sufficient genetic base for varietaladaptation and resistance;

7. supports viable farming enterprises andcontributes to livelihoods;

8. meets the cultural and social needs ofsociety.

Several approaches can be utilized tooperationalize GAP principles in potatoproduction. The most stringent one attachescriteria to each principle, with indicatorsand indicator values. For example, thefollowing table summarizes criteria,indicators, indicator values and GAPs thatcould be used in implementing principle4 above:


GAPs in the potato subsector

Conserving the natural resource baseCriteria

conserve soilorganic matter

percentage ofsoil organicmatter

5% organicmatter

apply compost, manure or green manureto keep soil organic matter at the desiredlevel

avoid soilerosion

surface run-offof soil particles

0 kg soil loss persquare meter peryear

apply contour farming, make terracesand use minimum or zero-tillageimplements

ensurereplenishmentof groundwaterused byirrigation

depth of thewater table

5 m belowtopsoil level

do not over-irrigate from deep wells andtap other water sources or growpotatoes during a wetter period of theyear if the threat of disease is not high.

Indicators Indicator values GAPs


“PACHAMAMA HUELLA” LAND PREPARATION

FOR POTATO IN BOLIVIA.(PHOTO: MANUEL SEOANE

SALAZAR)

In potato-based systems in developingcountries, the GAP concept can beassociated with critical productiondecision factors and recommendations.

Environmentand production zonesThe potato is essentially a “cool weathercrop”, with temperature being the mainlimiting factor. In tropical areas, potatoshould be grown where the climate istempered by altitude (1 500 – 4 200 m) orat lower altitudes provided the crop is grownduring the cool season.

The ideal condition for tuberization is anight temperature of around 16°C, whileoptimum yields are obtained where meandaily temperatures are in the 18-20°C range.Loose, moist and well-drained slightly acidsoil (with pH of 5.0-5.5) or volcanic uplandsoils are preferred. The water supply for thepotato crop should be regular, especiallyfrom the stage of tuber initiation until theend of tuber enlargement.

Cultivation methodsA successful potato crop depends onjudicious cultural practices. These includegood knowledge of variety purity andcharacteristics such as dormancy duration,the physiological condition of seed potatotubers (well sprouted and 30-80 g in weight,depending on variety) and resistance to themain transmissible potato diseases andnematodes.

Potatoes are best grown in rotation. Inthe Andes, it is usually the first crop in the

rotation. In other regions, it can be plantedafter cereals and before legumes, but notwith crops (e.g. tomato and othersolanaceae) that are susceptible to the samepathogens as the potato. Sometimes naturalfallow is necessary to prevent soilimpoverishment and the build-up of potato-specific diseases and insect pests.

Soil preparation for the potato cropshould be adequate with minimum soildisturbance. Naturally loose soils, andloamy and sandy loam soils that are rich inorganic matter with good drainage andaeration, are the most suitable.

Planting depth, density and spacingdepend on the variety chosen and tuber size,and should allow for shallow inter-rowridging, when required. Usually, about twotonnes of seed tubers are planted perhectare.

To give the crop a competitive advantage,weeding should be performed after full cropemergence (about 4 weeks after planting)and after the plants have reached a height ofabout 20 cm. Shallow ridging is donesubsequently to prevent the stolonsbecoming aerials, and to protect tubersagainst insect pests, disease infection andgreening. Crop rotation and carefulchemical control with herbicides, applied atminimum lethal doses, may be part of anintegrated weed management system,although in most developing countries weedmanagement is usually carried outmanually.

A few basic precautions against insectpests and diseases can help avoid great yield


Production decision factors


POTATO HARVESTINGIN PANUTY DISTRICT,NEPAL.(PHOTO: G.M. BAKASH)

and quality losses. They include croprotation, use of resistant varieties andhealthy, certified seed tubers (if available orat least seed from a reputed source orthrough positive selection), and integrateddisease and insect pest management, whichinvolves regular monitoring of aphid andthrips vectors, other insects and naturalenemy populations, and chemical sprayingonly when necessary.

Fertilizer application during the stagesof pre-planting, planting or crop growthshould be determined by soil nutrientavailability, taking into account thepotato’s high demand for potassium,phosphorus and magnesium deficienciesin acid soils. The NPK ratio 1-1-1 is usuallya wise choice to avoid spoiling tuberquality. The potato can benefit from theapplication of organic manure at the startof a new rotation as it provides a goodnutrient balance and protects soil structurefrom compaction and erosion.

As soil moisture must be maintained at arelatively high level in production ofpotatoes, compared to other crops, irrigationmay be required where rainfall is limited.

HarvestingFor most commercial varieties, yellowing ofthe potato plant’s leaves and easy separationof tubers from stolons indicate that thepotato crop has reached maturity. If thepotatoes are to be stored rather thanconsumed immediately, they are left in thesoil to allow their skin to harden – hard skinalso help seed potatoes to resist storagediseases. However, leaving tubers for toolong in the ground increases their exposureto the fungal disease black scurf andincreases the risk of losing quality andmarketable yield.

To facilitate harvesting and stop tubergrowth, potato vines should be removed twoweeks before the potatoes are dug up.Depending on the scale of the production,potatoes are harvested using a spading fork,a plough or commercial potato harvestersthat unearth the plant and shake or blowthe soil from the tubers. During harvesting,especially if it is done mechanically, it isimportant to avoid bruising or otherinjuries, which provide entry points forstorage diseases and reduce the commercial,processing quality and storability of thetubers.

In suitable environments and wheregrowing conditions are adequate,commercial yields are in the range of 40–60tonnes per hectare. In many developingcountries, however, they are far below thisfigure, with national averages of about 10-20 tonnes per hectare.



Storage and transportIn the tropics and where refrigerated storageis not available, seed tubers should be storedunder diffuse light in order to maintaintheir sprouting capacity and to encouragedevelopment of vigorous sprouts. In regionswith only one cropping season per year andwhere storage of tubers from one season tothe next is difficult without the use of costlyrefrigeration equipment, off-season plantingmay offer a solution. Importation of seedtubers is common in these regions, but mayentail higher costs and risks of late deliveryand deterioration in tuber quality along themarketing chain.

Ware potatoes should be kept at atemperature of about 6 to 8°C, in a dark,well ventilated environment with high

relative humidity (85 to 90 percent). Forprocessing purposes, such as the productionof french fries, storage temperatures mayrange up to 10°C to reduce the risk ofincreasing sugar levels, which areresponsible for a dark colour during frying.Potato darkening can also be caused by anexcess of nitrogen in the fertilizationformula.

During transport of seed tubers and wareand processing potatoes, it is important toavoid bruising by reducing drop height,lining containers with rubber or other softmaterial, and avoiding extremetemperatures. Tubers should be protectedagainst unexpected rainfall and snow, whichcan occur at high altitudes.


Documents

SECTION 1 Factors constraining the potato subsector · Factors constraining the potato subsector In the years ahead, world potato production is expected to grow at a rate of 2.5 per