Proceeduuts of the 7th International Working Conference on Stored-product Protection. - Volume 2

Grain postharvest status in Bhutan

Chetem Wangchen", George Srzedruckr'

Abstract

Bhutan is landlocked country situated on the southern slopesof the Himalayas With a range of chrnates , topographicfeatures and crops Rice, wheat and maize are the maincereal crops. The paper presents the current situation of thepostharvest in the gram sector With particular emphasis onthe drying operations

Introduction

Bhutan is situated between Chma m the North and India mthe South. The longitude of 900 east and the latitude of27.50 north run through the centre. The topography istotally mountainous With rugged terram imposmg severeresistance to any development activity The elevation rangesfrom 160metres above sea level m the South to more than7,550 metres above sea level m the North. SiX mam agro-ecological zones, from north to south have beendistmgtnshed: alpine, cool temperate, warm-temperate, drysub- tropical, humid sub- tropical, and wet sub- tropical Therainfall vanes from about 5500 rom m the narrow stnp ofwet subtropical region runrung along the border With India,to less than 650 rom m the alpme zone in the NorthDommated by the monsoon, the country has a great

vanety of different chmatic conditions Altitude andonentation of the land mainly influence rainfall andtemperature There can be considerable vanation in rainfallwithm relatively short distances due to ram shadow effectsand other factors, but precipitation generally dmumshesmarkedly from south to north The drversity of agro-ecological zones represents both a constraint as well as anopportunity The constraints anse m the research andextension efforts within a context of severe shortages ofprofessional staff The opportunity anses out of thepotential to satisfy ruche markets OWing to the specificenvironmental and resource related features for specIfiCproducts.

1Agnculture Machmery Centre, Paro, Bhutan

2 The Ulllversity of NSW, Sydney, Australia

Land Use

Forests form an integral part of the Bhutanese farmmgsystems wi th uses for firewood, fodder, manure andconstruction matenals The government has clearlypnontised the conservation functions of forests over itseconomic functions. Uuhzation is low and is a consequenceof the lack of extraction capabihtres, including theinadequate forestry management plans, and the extremelystnct restrictions on the use of forests for commercialloggmg Thus Bhutan has one of the highest per capitaprotected forests The total land area used for agriculture 1Sless than 12% .The country 1Sdivided by four major nver systems from

east to west. The economy 1Sbased pnmanly on subsistenceonented communities Agriculture is mtensrvely practiced toproduce mainly staple foods of nce and maize on small fieldsscattered on the steep mountain slopes. However, self-sufficiency in these basic cereals has not been achieved yet,resulting in the import of large quantities of nee and wheat.Agnculturalland 1S divided mto five categones based on

the land features and crops cultivated Wet land 1S terracedand bounded, and usually cultivated for paddy underirrigated but often ram-fed condition Dry land, usuallysloping fields and not terraced, are the common features forthe cultivation of dry land crops under ram-fed condition.Tsen or pangshmg land is under shiftmg cultivation and usedfor dry land crops once every frve to S1Xyears The otherland categones are kitchen garden and orchard mcludmgplantation Most of the agnculturalland is m the wet or dryland categones, which are about 24% and 52% of the totalarea respectively.Crop productivity 1Susually low due to traditional farmmg

with local varieties, and less development of farm land andirrigation facilities. Most of agncultural lands, except wetland, are not terraced or bounded. About half of wet land 1Sassumed to be ram- fed fieldsRice and maize are the mam cereals grown in all zones

except the western cool temperate zone where wheat,buckwheat, potatoes, mustard and barley are producedmstead Where rrngatlOn is avallable, wet land crops mwmter mclude wheat, mustard and potatoes although somemustard may be grown on reSidual soll mOlsture Maizera ther than nce occupy the largest area of the land m theEast where it const1tutes the mam diet. The only new baS1C

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Proceedings qf the 7 th Internatumal. W01'kingConference on Suned-proiuct Protection - Volume 2

food crop is the potato being cultivated in the temperate zonefor export mainly.

Introduction of new technology: The country had beenimporting various types of agricul tural machines,implements and tools from the neighboring countries alreadyseveral decades ago. However, planned activity started onlyin 1983 when Agriculture Machinery Center was startedwith the objective of mechanizing the farming activities.

Post-harvest in Grain

Drying is still traditional, with the maximum use of sundrying being made. Normally the crop is not harvested untilit is dry. After harvesting also in case of paddy, the crop isleft in the field to dry for several days (Fig. 1). If furtherdrying is required for storage, grains are spread on canvascloth or bamboo mats and taken out of the stores on sunnydays. Sometimes grain is dried by keeping it in flat bamboobaskets over the kitchen fire.

Fig.T, Field drying of paddy.

Cleaning is usually performed outside using screens andwind. Very simple forms of mechanical winnowing are beingcurrently introduced (Fig. 2).Due to poor drying methods, which are dependent upon

the weather, a lot of grain is lost to pests and moulds.Losses as high as 75 % are not uncommon. Spoilt grain isgenerally used as animal feed creating problems ofintoxication of livestock by mycotoxins. In some cases, inthe eastern part of the country, crops such as maize are soldoff in the market right after the harvest, only to be boughtback at higher prices later in the lean season. This is typicalfor maize grown in the subtropical regions, where thehumidity is high. This practice reflects the lack of storagefacilities and need of cash experienced by the farmers (Fig.3 and 4).

Fig. 2. Mechanical winnower used for paddy and wheat.

Fig.3. Typical drying method for maize.

Introduction of new drying methods, such as the flat beddryer using kerosene or electric burners, has not gainedpopularity. In fact beside the modern recirculating batchdryers using forced air circulation, used by the governmentorganizations, there are no other mechanical dryers used bythe private farmers on individual basis. There are severalreasons for this. Firstly, the landholding of individualfarmers being small, the quantity of the grain each farmerhas does not justify the investment in modern dryers, whichare imported. Secondly, new designs appropriate to the local

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Proceed'ings of the 7th International Working Conference on Stored-product Protection. - Vol'urne 2

technical and economic conditions are yet to be made. Inthis respect, the main reason is the lack of adequatetechnical know how within the backstopping institutions.There is also an obvious lack of awareness of the farmersabout the new postharvest technologies. The onlv area

where some appropriate dryer designs using locally availablematerials have been introduced is to dry mushrooms. Theseare firewood-based kilns. However, a significant effort hasto be made in order to improve their efficiency.

Fig. 4 . Storage of maize on cob in temporary bamboo sheds.

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