Eco friendly Solar Dryer : A boon to rural farmers
Dr S Roma Devi / L Kanta Singh *
Direct solar dryers :: Pix - Wikipedia/A.K.Karthikeyan
In many countries of the world, the use of solar thermal systems in the agricultural area to conserve vegetables, fruits, and other crops has shown to be practical, economical and the responsible approach environmentally. Solar heating systems to dry food and other crops can improve the quality of the product, while reducing wasted produce and traditional fuels - thus improving the quality of life, however the availability of good information is lacking in many parts of the countries where solar food processing systems are most needed.
Total population of Manipur as per 2011 census is 2,721,756 of which male and female are 1,369,764 and 1,351,992 respectively. In 2001, total population was 2,293,896 in which males were 1,161,952 while females were 1,131,944. Agriculture sector has a vital place in the economy of the state. It contributes a major share to the State Domestic Product 52.19 percent of the workers in Manipur are engaged as cultivators and agricultural labourers. However, the performance of agriculture in the state mainly depends on timely rainfall and weather conditions. Permanent cultivation is generally practiced in the valley districts while terrace cultivation is practiced in some pockets of the hills where jhuming or shifting cultivation is widely adopted in most of the hills.
Manipur is suitable for the development of horticulture. Besides, there is ample scope for bringing more land under fruits and vegetables cultivation in the hill areas as well as in the valley. The average annual productions of fruits and vegetables during the year 2007-08 were 2.74 lakh MT and 0.11 lakh MT respectively. The farmers have poor resource availability particularly where the vegetables are grown as subsistence crop by the small and marginal land holders.
In absence of proper storage technique the farmers usually sell their vegetables in the local markets soon after the harvest. Transporting their harvest in gunny bags on local transport to markets induced a considerable stress on them. Storage and upkeep of fruits and vegetables are most important post harvest activity. Due to lack of sufficient storage and processing facilities in most part of Manipur, considerable amount of fruits and vegetables are being spoiled after harvest. Losses occur in both ways i. e. qualitative and quantitative terms.
The spoilage of fruits and vegetables can be controlled up to some extend by drying of the products to optimum moisture content using eco friendly solar dryer. Solar drying has many advantages over the other forms of tradition dryers. Drying is an excellent way to preserve food and solar food dryers are an appropriate food preservation technology which is integral part of a sustainable agriculture.
Actually, solar food drying is one of the oldest agricultural techniques related to food preservation, but every year, millions of rupees worth of gross product are lost through spoilage. Reasons include, ignorance about preservation of produce, inadequate transportation systems during the harvest season, and the low price the rural farmer receives for products during the harvest season.
Drying of crops can change this trend and is useful in most part of the remote areas, especially those areas with lack of storage and scarcity of power supply, due to this problem; there is difficulty in expanding of modern storage facility. If drying of produce were widely implemented, significant savings to farmers would be achieved. These savings could help strengthen the economic situation of numerous poor farmers as well as improve in the nutritional diet of their daily intake.
Unfortunately many of the areas that could benefit from solar drying technology lack adequate information related to how to employ this technology and which technology to use under specific conditions. Many of the latest developments in solar drying technology, as well as significant achievements through applying this body of knowledge are not available to reach the farmers level and areas of greatest need. However, Krishi Vigyan Kendra has provided a new resource that helps bridge this information void.
Advantages of Crop Drying
- It provides early harvesting and reduces the field losses during harvesting,
- It provides better planning and control over the harvesting season,
- It reduces spoilage during storage,
- Better control over the market by the farmer to sell his product at better price during early period of harvesting season,
- Better quality of the product and better market value of the product,
- Reduce in transportation cost
- Availability of product round the year,
- More control of the market by the farmer,
- Reduces spoilage,
- Improves texture, taste, colour of the product,
- Improves drying hygiene,
- Improves storage capability,
- Reduces nutritional fluctuations
Very high temperature of Sun which produces radiations of shorter wavelengths falls over the solar dryer, the covered glass roof of the solar dryer allows radiations to pass through inside the chamber; these radiations are absorbed inside the chamber of the dryer and are re-radiated with longer wavelength in all directions at the earth’s temperature or inside the dryer’s temperature. Since longer wavelengths of radiations are not allowed to pass back through the covered glasses, hence thermal energies from the Sun are trap inside the box.
The solar cabinet dryer in its simple form consists of a wooden (or of any other material) box of certain width and length, insulated at its base and preferably at the sides and covered with a transparent roof. The inside as well as outside surfaces of the box are coated with black paint and the product to be dried is kept in the trays made of wire mesh bottom.
Door is provided on the either of side of the dryer for putting and removal of drying trays as and when required. Ventilation holes are made in the bottom through which fresh outside air is sucked automatically. Holes are also provided on the upper back sides of the dryer through which moist warm air escapes. This dryer has given encouraging results and reduced the drying time by one third compared to open sun drying.
In Manipur, varieties of fruits and vegetables are grown but due to lack of proper storage and processing facilities considerable amount of horticultural produce goes waste. Farmers are forced to sell their produce immediately after harvest, which lead to glut in market and resulting into lower return of their produce.
A simple cabinet solar dryer model having three trays made of locally available materials like wood and roof face covered with glass and painted the wooden body with black paint were tried by different KVKs of Manipur under ICAR Complex for NEH Region, Manipur Centre, Lamphelpat. It is very eco and farmers’ friendly technology. It requires low investment for construction and if the materials are available at farmers’ level it can be further more reduced in construction cost. Technology is so simple that local farmers could be trained to make their own low cost solar dryer and started utilizing it.
References:
1. http://en.wikipedia.org/wiki/Solar_dryer
2. http://desmani.nic.in/Economic%20Survey.html
3. http://solarcooking.org/drying/Whitfield-drying1.htm#_edn1
4. http://web.iitd.ac.in/~vkvijay/Biogas%20Technology.ppt
* Dr S Roma Devi and L Kanta Singh wrote this article for The Sangai Express
Krishi Vigyan Kendra ICAR Research Complex for NEH Region, Manipur Centre
This article was posted on March 14, 2013
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