Rice lodging is a common field disaster during the autumn harvest season, primarily caused by strong winds, heavy rainfall, field waterlogging, pest and disease infestations, and excessive panicle weight in the late growth stage. Based on actual field conditions, lodged rice is classified into four categories: slight lodging (lodging angle < 45°), moderate lodging (45° to 60°), severe lodging (> 60°), and irregular random lodging. Lodged rice features low-lying stalks and disordered plant posture. Conventional harvesting methods often lead to common issues such as uncut rice grains, grain dropping, harvester blockages, high broken rice rates, and grain entrainment, resulting in substantial yield losses and reduced harvesting efficiency. In accordance with the Technical Code for Loss Reduction of Rice Mechanized Harvesting (NY/T4963—2025) and combining practical experience of frontline agricultural machinery operators, differentiated and standardized operation methods tailored to various lodging conditions can effectively reduce harvesting losses and maximize rice yield retention in lodged fields. This article elaborates on practical mechanized harvesting technologies for lodged rice, covering machine selection, pre-harvest preparation, graded harvesting, parameter adjustment, and fault troubleshooting.

1. Scientific Machine Selection: Adapt to Lodging Conditions for Efficient and Low-Loss Harvest

Head-feeding and half-feeding combine harvesters differ greatly in structural performance and adaptability to lodged rice fields. Selecting the right machine based on the lodging degree and growth posture of rice is the core premise of low-loss and high-efficiency harvesting.

1.1 Half-feeding Combine Harvester

This type of harvester boasts the best adaptability to lodged rice, especially suitable for fields with moderately and severely lodged rice in a uniform direction. It clamps and transports only the lower part of rice stalks during harvesting, maintaining complete stalk integrity. The feeding and grain lifting processes are stable, effectively avoiding grain dropping and stalk entrainment while ensuring a lower broken rice rate. It delivers prominent yield-increasing and loss-reducing effects for fields with large and uniform rice lodging angles.

1.2 Full-feeding Combine Harvester

Featuring strong versatility, full-feeding harvesters are ideal for fields with slightly lodged rice, irregularly lodged rice, and dense rice stalks. For lodged rice harvesting, the machine must be equipped with professional accessories including rice lodging lifters, anti-lodging spring tines, and extended crop dividers. These accessories solve core problems such as difficult crop division for low-lying stalks, uneven feeding, and stalk accumulation, greatly improving the machine’s adaptability to lodged fields with outstanding cost-performance.

1.3 Field Selection Principles

Half-feeding harvesters are preferred for neatly lodged fields with uniform and large lodging angles. Full-feeding harvesters are the first choice for complex fields with irregular and mixed-degree lodging. Matching the machine model to field conditions effectively avoids excessive harvesting losses and frequent equipment failures caused by model mismatch.

2. Pre-harvest Preparation: Pre-control to Eliminate Hidden Harvest Risks

Lodged rice fields feature complex operating conditions with humid, flexible stalks and disordered plant distribution. Sufficient pre-harvest preparation including field investigation, machine maintenance, and parameter presetting is essential to minimize equipment failures and grain losses from the source.

2.1 Field Investigation and Operation Planning

Conduct on-site field surveys before formal harvesting to clarify the rice lodging degree, overall lodging direction, soil muddy condition, and field water accumulation, then divide the field into reasonable operation zones and formulate harvesting routes. For waterlogged and muddy fields, drain water and dry the field in advance to prevent harvester sinking and blockages of the header and cleaning sieve caused by muddy stalks. Mark areas with severe lodging separately for subsequent low-speed refined harvesting.

Reasonably arrange the operation time: the optimal harvesting period is from noon to evening on sunny days when dew is completely evaporated. Dry rice stalks with moderate toughness avoid adhesion and accumulation on the harvester, effectively reducing grain dropping. Avoid harvesting in dewy mornings and rainy days entirely.

2.2 Machine Maintenance and Accessory Installation

Fully inspect and maintain core harvester components to ensure optimal equipment condition: polish dull cutter blades to guarantee smooth cutting, check the tension of conveyor belts, remove residual stalks and debris from threshing drums and sieves, and debug the braking and walking systems for stable operation.

Install targeted accessories according to machine types: full-feeding harvesters must be fitted with lodging lifters and anti-lodging spring tines to enhance low-position grain lifting capacity for low-lying stalks; half-feeding harvesters need adjustable grain lifting claws and crop dividers to adapt to lodged plant postures. Prepare wearing parts such as spare blades, spring tines, and conveyor belts in advance for rapid on-site replacement and reduced operation downtime.

2.3 Basic Parameter Presetting

The parameter settings for lodged rice harvesting differ significantly from those for upright rice. Complete basic parameter debugging before operation: properly lower the header and reel position, and reduce the harvester’s traveling speed and threshing drum speed. This reserves adjustment space for fine on-site tuning and ensures smooth subsequent operation.

3. Graded Harvesting: Differentiated Operation Based on Lodging Degree to Control Losses

Rice with different lodging degrees varies greatly in harvesting difficulty and loss risk. Uniform operation modes are not applicable. Targeted and classified harvesting strategies are required to minimize grain dropping and uncut losses.

3.1 Slight Lodging (Lodging Angle < 45°)

Slight lodging has little impact on mechanized harvesting, requiring only optimized conventional operations rather than excessive refined adjustment. Harvest along the rice lodging direction at a constant medium-low speed. Avoid high-speed operation which may topple remaining upright rice and cause secondary lodging and artificial missed cutting.

Set the cutter height at 3 to 5 cm above the ground to ensure complete harvesting of rice panicles. Slightly lower the reel to smoothly guide lodged stalks into the header, controlling grain losses within the standard range.

3.2 Moderate Lodging (45° to 60°)

Moderate lodging is the critical node for harvesting loss control and the key focus of loss reduction management. Prioritize harvesting against the lodging direction, using the reel and lodging lifting devices to reverse and lift low-lying stalks, significantly improving harvesting cleanliness.

Operate at a constant low speed to reduce single-time stalk feeding volume and prevent stalk accumulation and blockage of the header and threshing drum. For model-specific adjustment: lower the front crop divider and appropriately raise the grain lifting claws of half-feeding harvesters to accurately clamp lodged stalks; narrow the working cutting width of full-feeding harvesters to ensure uniform feeding and avoid equipment failures caused by excessive local feeding.

3.3 Severe Lodging (> 60°, Ground-hugging Lodging)

Severe ground-hugging lodging poses the greatest harvesting difficulty. Half-feeding harvesters with superior adaptability are prioritized for such fields. Operate at the lowest traveling speed and lower the header to the minimum cutter height of about 3 cm above the ground to harvest ground-hugging panicles as completely as possible.

Adopt reverse harvesting as the main method, combined with oblique alternate harvesting for uniformly lodged fields to solve the problem of unharvestable low-lying stalks. Manually comb and assist feeding for a small number of fully ground-hugged blind areas to avoid large-area yield loss. Avoid sudden acceleration and shutdown during operation to prevent disordered stalk accumulation and grain dropping.

3.4 Irregular Random Lodging

Irregularly lodged fields feature staggered stalk heights and disordered lodging directions. Full-feeding harvesters with strong adaptability and wide feeding width are preferred. Abandon unified harvesting routes and adopt zoned and layered progressive harvesting. Adjust the harvesting angle slightly and frequently during operation to adapt to disordered stalk distribution.

Maintain low speed and narrow cutting width throughout the operation to prevent machine blockage caused by centralized feeding of disordered stalks. Increase field inspection frequency to remove winding stalks timely and ensure continuous and stable operation.

4. Fine Tuning of Core Parameters for Quality Improvement and Loss Reduction

The key to loss-reducing harvesting of lodged rice lies in the precise matching of harvester parameters and field conditions. Targeted debugging of core components including the reel, header, threshing drum, and cleaning sieve effectively solves uncut rice, grain dropping, broken rice, and grain entrainment problems, improving overall harvesting quality.

4.1 Reel Debugging

Follow the three core debugging principles for lodged rice reels: lower height, forward displacement, and lower speed. Reduce the overall reel height to allow spring tines to reach the bottom of stalks and stably lift ground-hugging rice. Displace the reel slightly forward to complete grain lifting and guiding in advance and avoid stalk accumulation at the header front. Reduce the reel speed to prevent grain dropping caused by high-speed tine impact on panicles, cutting off source losses fundamentally.

4.2 Header and Traveling Speed Debugging

Low cutting height is mandatory for lodged rice harvesting to avoid missing ground-hugging panicles due to excessive stubble height. Reduce the working cutting width by 1/4 to 1/3 compared with upright rice harvesting to lower single-time feeding pressure and ensure smooth stalk transportation.

Operate at a constant low speed without high-speed rushing. This effectively reduces stalk blockages and grain dropping risks. Field verification shows that standardized low-speed operation can reduce harvesting losses by more than 15%.

4.3 Threshing and Cleaning System Debugging

Lodged rice stalks are humid and highly flexible, requiring optimized threshing and cleaning parameters. Reduce the threshing drum speed and appropriately increase the drum gap to avoid excessive broken rice and stalk blockages caused by high-speed extrusion and narrow-gap friction. This ensures thorough threshing while lowering the broken rice rate.

Meanwhile, reduce the fan cleaning wind speed and slightly narrow the sieve opening to adapt to humid and fine stalk debris, preventing light rice grains from being blown away by excessive wind speed and reducing cleaning-link grain losses.

5. Operation Process Management and Fault Emergency Handling

The complex working conditions of lodged rice harvesting easily cause common faults such as machine blockages, harvesting losses, and grain entrainment. Strict whole-process operation management and rapid emergency fault handling are critical to stabilizing harvesting efficiency and controlling losses.

5.1 Routine Operation and Maintenance Management

Implement regular shutdown maintenance. Clean winding stalks, soil, and debris on the cutter, feeding cylinder, threshing drum, and vibrating sieve every 1 hour of continuous operation to prevent accumulation blockages and quality degradation. Monitor harvesting conditions in real time during operation. Stop and fine-tune parameters immediately if increased uncut areas, severe grain dropping, or uneven feeding are observed, avoiding faulty operation.

Further reduce traveling speed and adopt the low-volume frequent-feeding method for muddy wet fields to prevent machine adhesion and faults caused by wet stalks and soil.

5.2 Emergency Handling of Common Faults

Header Blockage: Mainly caused by excessive feeding volume and humid disordered stalk accumulation. Shut down the machine completely to clean blocked stalks and debris, then narrow the cutting width and reduce traveling speed before restarting operation.

High Grain Entrainment Loss: Caused by excessive drum speed, insufficient threshing gap, or mismatched cleaning wind speed. Reduce the drum speed, properly expand the threshing gap, and adjust the fan wind speed synchronously to improve threshing and cleaning cleanliness and reduce grain entrainment.

Severe Uncut Rice: Primarily resulting from excessive stubble height and poor reel lifting effect. Lower the header and stubble height, fine-tune the reel position and speed, and switch to reverse harvesting routes to enhance grain lifting and harvesting effects.

6. Post-harvest Finishing and Core Loss Reduction Summary

The core practical principles for mechanized harvesting of lodged rice are summarized as: lift first, harvest later; low-speed stable feeding; parameter adaptation; and graded operation.

After harvesting, thoroughly clean residual grains and stalks inside the harvester, inspect the wear of core working components, and complete machine cleaning, maintenance, and storage. Conduct manual supplementary harvesting for field edge blind areas and uncut zones to maximize yield recovery.

Different from conventional upright rice harvesting, lodged rice harvesting cannot prioritize operation speed, but must focus on "low loss and high cleanliness". Scientific machine selection, precise parameter tuning, and standardized operation based on field lodging degrees and soil conditions can control mechanized harvesting losses within the industry standard range, effectively solving common problems such as uncut rice, grain dropping, and machine blockages. This maximizes the yield of lodged rice fields and provides solid mechanized technical support for stable grain production and income growth.