Combine harvesting

In India, China, Thailand, Vietnam and even in Cambodia the use of combine harvesters, or simply combines, for paddy rice is increasing rapidly.  This is a development due to severe labor shortage and the resulting increase in harvesting cost, which makes the use of combines economically attractive. Combines “combine” several operations into one: cutting the crop, feeding it into threshing mechanism, threshing, cleaning, and discharge of grain into a bulk wagon or directly into a bags. Straw is usually discharged behind the combine in a windrow.

Click here for a description of the components of a combine.

Examples of combines common in Asia

	"Mini Combine" Principle: Axial-flow Cutting width: 1-1.5m Capacity: 1-1.2ha/day Usage in Vietnam, Philippines, China Cost: US$ 5,000-10,000 Development: Developed based on a Chinese unit by Briggs&Stratton (B&S) and the Philippine Rice Research Institute (PhilRice). In VIetnam collaboration between B&S and Nong Lam University (NLU) leading to commercial production by South Vietnam Engine and Agricultural Machinery (SVEAM), formerly VINAPRO. Usage: Commercial production in Vietnam and in the Philippines. By 2010 machines in operation in Vietnam, Cambodia, Lao PDR, the Philippines and export of several machines from Vietnam to Africa.
	Axial flow combine Principle: Axial flow Cutting width: 3m Capacity: 0.8-1.3 ha/h Cost: US$ 60,000-80,000 Usage: By 2010 very popular in Thailand, also exported to neighboring countries with increasing numbers in Cambodia.
	Conventional combine Principle: conventional with staw walkers. Cutting width: 3-4.5m Capacity: ?? Cost: ??? Usage: In India in rice-wheat systems, used with high yielding rice varieties but not suitable for Basmati.

Combine ownership and usage

Generally only larger farms or stations will own a combine harvester, and smaller farms avail of the services of contractor. Successful use of combine harvester requires well-drained, leveled fields with a layout that minimizes the number of turns required in the field. Some rice combines arre also equipped with tracks instead of wheels for better mobility in wet fields.

Guidelines for good combine harvesting methods/recommended practices

• Cutting height during combine harvesting is often higher than with other harvesting methods.
• Choosing time interval for harvest by combine harvester is often narrow: too early harvesting will result in a high percentage of chalky kernels, and too late harvesting will result in high shattering losses.
• 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.
• Fine tuning forward speed and header height is especially important to minimize field loss.