Mechanisation as a tool for modernisation of agriculture has been well recognised as it generates greater crop intensity and as such improves productivity. It results in considerable saving of fodder and feed by reducing use of bullock.

A transition from subsistence to commercial farming can only be achieved through the transfer of the latest, most effective technology to the farming system.

The rice post-harvest operations require improvement in the use of resources for research and development, particularly with regard to the level of post-harvest losses. These losses are attributed to a combination of factors during production and post-production operations.

Mechanisation of paddy threshing is an unresolved issue of farmers particularly in Sindh. Paddy harvesting and threshing is not fully mechanised in Pakistan and is generally done manually except on limited areas of Punjab where combine harvesters have recently been introduced.

Paddy threshing is a labourious task and more difficult during the inclement weather and labour shortage during peak season. Threshing operation which involved separation of paddy from spike lets is one of most important part of harvest operations.

Threshing of rice is still being done by traditional methods like drum beating, bullock treading and tractor over harvested crop. The efficiency of traditional methods is low coupled with problems leading to delay in handling a large volume of crop, rotting of stacked, eating by rodents, other animals, birds and also the damage of crop through violent winds, storm, rain, pilferage and fire hazards at threshing floor. Consequently, there is a tremendous loss of the produce in manual threshing.

In order to mechanise paddy threshing, a tractor operated high capacity (throw in-type) paddy thresher was introduced by Farm Machinery Institute, NARC. The machine has been tested in Sindh to assess its performance in the local conditions. The test results were encouraging.

The cost of threshing with traditional methods is also very high as compared to threshing machine.

Together with the high amount of grain losses and high cost of operation with manual methods, the labour requirements are also high. The labour requirements for manual threshing and cleaning is 250 man hours/hectares as compared to mechanical threshing and cleaning which is 20 man hours/hectare.

In Pakistan, paddy grain is mostly threshed manually. It is slow and great drudgeries process. A low cost power operated simple thresher has been developed. The power operated unit working on 65Hp and has the capacity to thresh 1.5–2 tons of paddy an hour. This machine threshes the paddy as well as separates the grain with 99pc efficiency.

The thresher is operated like conventional wheat thresher by tractor PTO. Its threshing mechanism is based on well-known axial-flow system. Operating thresher speed either too fast or too slow reduces profit. The optimum thresher speed depends on grain moisture content, volume of material entering into the combine, weeds, etc.

The survey results reveal that 41pc growers used paddy thresher. The availability of thresher was investigated and found that a very few threshers are available in the area. Hence, growers have to wait about 10 to 15 days for thresher. Growers usually pay threshing charges in kind (3kg/40kg ).

The labour days and their cost for harvesting were collected from the paddy growers. The harvesting operations consists of harvesting, bundle making, preparation of threshing yard and collection and shifting of paddy to threshing yard.

The results indicate that over all 22 man days are required for harvesting operation of one acre of paddy field. Results further indicate that on an average paddy growers spent Rs1,320 per acre including Rs780 for harvesting, Rs180 for bundle making, Rs120 for preparation of threshing yard and Rs240 for collection and shifting of paddy to threshing yard.

The labour man days for different threshing methods were collected from the paddy growers and found that 20 man days per acre is required for drum beating followed by nine man days for bullock threshing, six man days for tractor threshing and three man days for thresher. The wages were also calculated and found that labour for thresher charges was high at Rs150 per day compared to other methods of threshing.

To maintain the high quality of the harvested grains, it should be threshed immediately after harvesting. Avoid field drying and stacking for several days as it affects grain quality due to over drying. Stacked grains of high moisture content results in discolouring or yellowing. Survey results indicate that in drum beating method five days are required for threshing one acre, by tractor 2.4 days, by bullock 3.1 days and paddy thresher needs two hours for threshing one acre paddy.

Grain broken percentage in different paddy threshing methods were examined and found that more grain broken percentage was recorded in paddy thresher 5.03pc, followed by 2.12pc in drum beating, 2.33pc in animals and 2.30pc in tractor.

Yield of paddy under different paddy threshing methods were recorded and found that growers who used thresher take more yield 61.7 maunds per acre of Irri and 42.6 maunds of super basmati varieties compared to other threshing methods.

Market value of paddy threshed under different threshing methods were examined and found that growers received highest price of paddy threshed with drum beating Rs305 per 40-kg for Irri and Rs507 per 40-kg for super basmati varieties followed by bullock threshing Rs300 per 40-kg for Irri and Rs498 per 40-kg for super basmati varieties. Paddy threshed with thresher received lowest rate Rs292 per 40-kg and Rs488 per 40 kg for Irri and super basmati varieties. Reasons for low price were reported due to high moisture content and grain broken percentage.