Mechanized rice harvesting is a core link to stabilize yield, increase income and reduce labor costs in modern rice planting industries. Compared with traditional manual harvesting, a combine harvester can complete multiple processes in one pass, including reaping, threshing, cleaning and straw disposal. It greatly improves operating efficiency, effectively solves the pain points of manual harvesting such as time consumption, high grain loss and tedious drying work, and seizes the optimal farming window to avoid yield losses caused by extreme weather. Standard operation of rice harvesters gives full play to equipment performance, extends machine service life, controls harvesting loss, and maximizes grain recovery. Combining front-line field operation experience and official agricultural machinery technical standards, this article systematically sorts out the full-process practical guidelines for rice harvesters, covering pre-harvest preparation, parameter adjustment, field operation, post-work maintenance and safety specifications, which adapts to various rice planting areas and mainstream harvester models.

1. Pre-Harvest Preparation: Lay a Solid Foundation and Avoid Potential Risks

Before formal harvesting, three essential preparatory tasks must be completed: rice growth condition assessment, field environment inspection, and comprehensive machine inspection. Adequate pre-harvest preparation is a prerequisite for low-loss, high-efficiency and safe operation. Negligence in any link may lead to mechanical failures and unnecessary grain loss.

1.1 Determine the Optimal Harvest Time

The maturity of rice directly determines harvesting quality and grain loss rate. Early harvesting results in insufficient grain plumpness, high proportion of unfilled grains, and reduced overall yield and quality. Late harvesting easily causes natural grain shedding, pre-harvest sprouting and straw breakage, leading to avoidable yield loss. The optimal field harvesting standard is as follows: the whole rice field reaches 90% maturity, two-thirds of the grains on each ear are fully mature and hardened, and the straw still maintains proper toughness.

For commonly planted indica rice and japonica rice, the optimal grain moisture content for harvesting is 22% to 28%. Excessively high moisture content makes threshing and cleaning difficult and easily causes blockage of screens and threshing drums. Excessively low moisture content makes rice ears dry and fragile, significantly increasing field grain shedding loss. Adjust the harvesting time according to rice varieties: harvest hard-to-thresh rice 1 to 2 days in advance, and delay harvesting for easy-to-thresh varieties to balance operating efficiency and harvest quality.

1.2 Select the Right Harvester Model According to Working Conditions

There are two mainstream types of rice combine harvesters widely used in domestic rice fields: full-feed and half-feed harvesters. Farmers and machine operators shall select suitable models based on rice growth height, straw density and field conditions to avoid operational stuttering and poor harvesting quality caused by model mismatch.

1. Full-Feed Harvester: Suitable for rice with a plant height above 110cm, dense straws and slight lodging. This model features strong versatility, fast operation speed and high load capacity. It is the mainstream equipment for large-scale harvesting in flat and contiguous rice fields.

2. Half-Feed Harvester: Suitable for rice with a plant height of 65 to 110cm and an ear height difference within 25cm. It delivers high threshing accuracy, low broken rice rate and minimal grain loss. It is ideal for high-quality and high-value fragrant rice, as well as hilly terraces and small scattered fields.

1.3 Clean and Inspect the Field Operating Environment

Thoroughly remove field obstacles such as stones, tree roots, iron wires and hard sundries before operation to prevent impact damage to high-speed rotating cutter bars and threshing drums, and avoid mechanical failures and safety hazards. Inspect field water accumulation and silt depth in advance, and formulate operation routes for deep silt fields to prevent machine sinking and stalling. Clean ridge weeds and field edge sundries to ensure unobstructed harvester passage and operation.

1.4 Comprehensive Machine Inspection and Pre-Operation Maintenance

Operating faulty equipment is a taboo in agricultural machinery work. In accordance with industry operation specifications, conduct a full machine inspection before the harvesting season and routine daily pre-operation checks to eliminate potential hazards in advance.

1. Power System: Check whether the liquid levels of engine oil, coolant and fuel meet standards. Clean crop residues and dust on radiators and water tanks to prevent engine overheating and shutdown. Inspect drive belts for cracks, looseness and slipping, and keep proper tension.

2. Operation System: Focus on inspecting core components including cutter blades, conveyor chains, threshing drums and cleaning screens. Ensure blades are sharp and free of curling edges, conveyor chains are properly tensioned without stuttering, and screens are intact without damage or deformation. Fasten all body screws and connectors to prevent component falling off caused by operation vibration.

3. Travel and Braking System: Check the tension of crawlers or tire pressure, and adjust loose crawlers to avoid driving deviation. Test the sensitivity of brakes and steering repeatedly to ensure stable and reliable traveling, turning and braking performance in fields.

4. Auxiliary System: Verify the normal operation of warning lights and working lights. Adjust straw chopping and throwing devices, and turn on the straw returning function according to planting needs to facilitate subsequent tillage and land preparation.

2. Startup Parameter Adjustment: Adaptive Fine-Tuning for Field Conditions

Do not start formal operation immediately after machine inspection. Targetedly adjust equipment operating parameters according to real-time rice growth, field humidity and soil dryness. Accurate parameter adjustment is critical to reducing harvesting loss and mechanical failure, serving as a key control link in field operation.

2.1 Cutter Bar Height Adjustment

The core principle of cutter bar height control is reasonable stubble height, minimal grain loss and anti-blocking performance. For normally growing rice, keep the stubble height at 10 to 15cm. For lodged rice, properly lower the cutter bar close to the ground to reduce missing harvest and residual ears. For tall rice, raise the cutter bar appropriately to prevent excessive straw from entering the machine and blocking the drum and conveyor channel. Fine-tune the height in real time according to rice growth to ensure neat stubbles without ear tearing or missing cutting.

2.2 Operating Speed and Feed Rate Adjustment

Harvester traveling speed directly determines the straw feed rate per unit time, and improper speed control easily causes operational failures. Excessively fast speed leads to overloaded feeding, incomplete threshing and machine blockage. Excessively slow speed reduces working efficiency and delays farming schedules. For uniform and moderately dense rice fields, control the traveling speed at 3 to 5km/h. For high-density, high-humidity and heavily lodged fields, reduce the speed to 2 to 3km/h to lower the feed rate and ensure thorough threshing and cleaning. Maintain uniform traveling speed throughout the operation and avoid erratic speed and frequent start-stop.

2.3 Threshing and Cleaning Parameter Adjustment

Adjust drum speed and fan air volume flexibly according to rice varieties. For easy-to-thresh conventional rice, properly reduce drum speed and fan air volume to avoid grain breakage and wind loss. For hard-to-thresh hard rice seeds and late-maturing rice, increase drum speed and air volume to ensure complete threshing and thorough separation of grain from straw impurities. Fine-tune the inclination angle of the cleaning screen to guarantee qualified grain cleanliness and impurity content within industry standards.

3. Standard Field Operation Procedures: Standardized Practice for Quality Improvement and Loss Reduction

After parameter adjustment, carry out harvesting work following the standardized process of uniform linear operation, standard headland turning, edge supplementary harvesting and real-time operation inspection to avoid common problems such as missing harvest, repeated harvesting and high grain loss.

3.1 Formal Startup and Operation

Start the engine and idle for 3 to 5 minutes until the machine runs stably with normal parameters. Slowly lower the cutter bar, engage the working clutch smoothly, and start harvesting at a constant speed. Keep linear and uniform traveling during operation. Avoid sudden acceleration, emergency shutdown and high-speed turning, which cause uneven feeding, machine blockage and grain shedding. Adopt linear harvesting for large fields to achieve better flatness and higher efficiency.

3.2 Headland Turning and Field Connection Operation

Headland and ridge turning are the links most prone to loss and failure. Strictly follow the procedure: raise the cutter bar first, suspend operation, complete turning, and then lower the cutter bar to resume work. Never turn with the cutter bar lowered. Adopt right-angle circling or reverse turning in daily operation. Reverse 8 to 10 meters before turning to adjust the machine position, align the working width accurately, and then continue harvesting. Ensure precise connection between adjacent working strips without gaps or overlapping to eliminate missing and repeated harvesting.

3.3 Supplementary Harvesting for Edge and Dead Zones

For narrow corners and ridge edges inaccessible to large harvesters, conduct low-speed supplementary harvesting after the completion of large-area operation via oblique cutting. Manually clean residual ears in blind spots unreachable by machinery to ensure no grain is left in the field and maximize harvest rate.

3.4 Real-Time Operation Inspection

Operators shall monitor machine operation status and harvesting quality throughout the work, and conduct a comprehensive inspection every half an hour. Focus on checking threshing cleanliness, grain purity and field shedding loss; examine blockages in cutter bars, conveyor channels and threshing drums; monitor engine water temperature, operating speed and abnormal machine noise and vibration. Immediately stop the machine to adjust parameters if excessive grain entrainment, wind loss or blockage occurs. Never operate with faulty equipment to avoid failure escalation and increased yield loss.

4. Core Loss Reduction and Common Failure Prevention Skills

Grain loss control is the core priority of rice mechanical harvesting. The industry standard for total rice harvesting loss rate is no more than 3%, while standardized and refined operation can control the actual loss rate within 1.5% to maximize grain yield. The core front-line operation skills are as follows:

1. Operation for Lodged Rice: For severely lodged rice, adopt reverse or oblique harvesting at a low speed. Lower the cutter bar, sort lodged straws gradually and harvest slowly to reduce missing harvest and grain shedding loss.

2. Operation in Humid and Rainy Weather: Rice and straw have high moisture content in rainy and high-humidity conditions, which easily causes machine blockage. Reduce traveling speed and feed rate, appropriately increase fan cleaning air volume, and regularly clean straw accumulation on screens and drums to prevent impurity buildup, grain mildew and incomplete cleaning.

3. Standard Blockage Handling: Once straw or impurity blockage occurs, shut down the machine and cut off the power immediately. Never clean blockages by hand or with tools while the machine is running to prevent mechanical injury. Conduct no-load trial operation after cleaning to confirm normal operation before resuming harvesting work.

5. Post-Operation Finishing and Daily Machine Maintenance

Daily cleaning and maintenance after harvesting directly affect machine service life and secondary operation performance. Standardized post-work maintenance effectively reduces failure rate and long-term maintenance costs. The specific operation specifications are as follows:

1. In-Depth Machine Cleaning: After shutdown, thoroughly remove residual straw, chaff, sediment and scattered grains from cutter bars, threshing drums, cleaning screens and machine gaps. Long-term residue accumulation will cause mildew, component corrosion and secondary blockage in the next operation.

2. Core Component Inspection: Check blade wear, chain tension and belt aging, and replace severely worn and loose accessories in a timely manner. Fasten loose screws and sealing parts, and check oil and water circuits for leakage.

3. Machine Maintenance and Storage: Clean the air filter element, and replenish engine oil, fuel and coolant as needed. Wipe off water and sediment on the machine surface to keep it dry and clean. Take rainproof and sunshade measures for outdoor parking. Conduct anti-rust treatment and sealed storage for long-term idle equipment to prevent aging and damage.

6. Safety Operation Specifications

1. Harvester operators must receive professional systematic training and be proficient in machine structure, operation procedures and safety rules. Untrained and inexperienced personnel are prohibited from independent operation. Operators shall wear tight work clothes and avoid wearing scarves and loose gloves that are prone to winding risks.

2. Keep away from rotating and transmission high-risk components during machine operation. Climbing and straddling running harvesters are strictly prohibited. Always pay attention to surrounding personnel and field obstacles during operation to prevent safety accidents.

3. Strictly abide by operation disciplines. Drunk, fatigued and sick operation is forbidden. Stop field harvesting immediately under extreme weather such as high temperature, heavy rain and strong wind to ensure personal and equipment safety.

7. Industry Summary

Standardized rice harvester operation relies on full-process control: accurate pre-operation preparation, standardized in-operation execution and refined post-operation maintenance. Every detailed specification including harvest timing judgment, model selection, parameter debugging, field loss reduction, failure prevention and safety maintenance is the key to efficient, high-quality, low-loss and safe mechanical rice harvesting. With the large-scale and standardized development of modern agriculture, proficient harvester operation skills can effectively reduce grain harvesting loss, improve rice commodity quality, lower machine failure frequency and save operation and maintenance costs, providing solid technical support for stable yield, income increase and intensive development of rice planting industry.