Scientist's Response | Luo Xiwen: Difficulties in Cultivation in Hilly Areas? These Assistants are Here to Help

Editor's Note: Since May 2023, the "Study China" learning platform, in collaboration with the China Science Daily, has launched the "Scientists' Response" initiative, inviting readers to ask questions and leave messages for the scientists and technologists they admire. Since its inception, the platform has received enthusiastic responses from readers. We have selected a question from reader Yi Wenxiu and invited academician of the Chinese Academy of Engineering and professor at South China Agricultural University, Luo Xiwen, to respond in the forty-ninth issue.

With questions that seek knowledge igniting scientific discussions, and interactive responses sparking new scientific insights, "Study China" and the "Science Net App" aim to serve as messengers between the public and science. We welcome you to continue leaving your comments in the discussion section. Reader Yi Wenxiu: I'd like to ask scientists if there are any machinery suitable for farming in the mountains?

Luo Xiwen: Mechanization of agriculture in hilly areas is a challenging and focal point of agricultural mechanization in China. After years of efforts by domestic agricultural machinery workers and enterprises, there are now some machinery options available with good performance.

Agricultural mechanization in hilly areas mainly involves machinery for operations such as plowing, planting, pest control, and harvesting. From the perspective of agricultural mechanization, there is not much difference between the machinery used in 2-6 degree gentle slopes in hilly areas and those used in plains with slopes below 2 degrees. Slopes of 6-15 degrees are suitable for medium and small-sized agricultural machinery, while slopes of 15-25 degrees are suitable for small-sized agricultural machinery. Land with slopes of over 25 degrees is not suitable for cultivation and should be preserved as ecological reserve land for planting trees or grass.

Fields in hilly areas are fragmented, infrastructure is weak, there is a lack of supporting machinery roads, and irrigation facilities are inadequate. It is difficult for agricultural machinery to operate in these conditions, making mechanization challenging. Large-scale agricultural machinery is not suitable, with medium and small-sized agricultural machinery being the main option.

For plowing operations in hilly areas, medium and small-sized tractors equipped with rotary tillers or micro-tillage machines can be used. Planting can employ medium and small-sized power-matched broadcasting or transplanting machinery, pest control primarily utilizes drones, and harvesting is mainly done with medium and small-sized combined harvesters or portable harvesters. By selecting different power machinery and equipment, the mechanization challenges of major crops in hilly areas can be addressed. Compared with non-mountainous agricultural machinery, mountainous agricultural machinery requires features such as compact structure, light weight, small turning radius, good ground adaptability, stability, good climbing performance, and good anti-rollover performance.

Taking the cultivation and harvesting stages of rice production as an example, the following is an introduction to the matching scheme of agricultural machinery suitable for major stages of agricultural production in hilly areas, for your reference. However, it is recommended that you contact the manufacturers directly and communicate your specific needs to them for their advice.

Plowing:

1. Medium and small-sized tracked tractors + rotary tillers Tracked tractors are equipped with high-pattern rubber triangular tracks, which have a small ground pressure, do not slip on wetlands, and have low subsidence in paddy fields. They have strong obstacle-crossing ability in hilly areas. With a standard three-point suspension device, they can be connected and driven with standard agricultural machinery. By equipping different agricultural implements, tasks such as plowing, rotary tillage, leveling, ridging, trenching, seeding, soil cultivation, hole punching, transportation, pumping, spraying, and earthmoving can be completed. The power ranges from 10 to 35 kilowatts, and the working efficiency is 2 to 5 mu per hour, suitable for paddy fields and various dryland scenarios.
2. Tracked Tractor + Rotavator
3. Hand-Held Wheel Tractor + Rotavator

Small hand-held wheel tractors paired with rotavators enable efficient tilling of small plots in hilly and mountainous areas, boasting good maneuverability on slopes and across field ridges while maintaining normal operating speeds. With various attachments, these tractors can accomplish tasks such as plowing, tilling, leveling, ridging, trenching, seeding, transporting, and irrigation pumping. They typically feature a power range of 8 to 15 kilowatts and achieve operational efficiencies ranging from 1 to 3 acres per hour, suitable for both paddy fields and various dryland scenarios. 图2: 手扶轮式拖拉机+旋耕机

二、种植

在水稻的种植过程中，可采用机械直播和机械插秧两种方式。水稻直播机分为水直播机和旱直播机两种，而机械插秧则主要有手扶式插秧机和高速乘坐式插秧机两种。手扶式插秧机和小型水稻直播机可以满足山地丘陵、小田块以及个人种植者的插秧需求。

1. 小型水稻直播机

   小型水稻直播机与手扶式插秧机头配套，能够一次完成开沟和播种作业。其播种量调节范围为1.5～10千克/亩，可选的行距包括20/25/30厘米三种，播种行数为4～6行，穴距可调节在10～25厘米之间。播种合格率高达92%以上，能够满足杂交稻和常规稻的精量直播需求，作业效率可达每小时2～3亩。适用于丘陵山区的小地块水田直播作业。 Figure 3: Handheld Rice Transplanter

2. Handheld Rice Transplanter

The handheld rice transplanter offers a row spacing choice of 25/30 centimeters, with four rows available for planting. The plant spacing is adjustable between 12 to 28 centimeters, and the transplanting depth can be set between 7 to 21 millimeters. It boasts a productivity rate of over 1 acre per hour, making it suitable for mechanized transplanting operations in small paddy fields located in hilly and mountainous regions. Caption: Figure 4 - Handheld Transplanter

The Small-Scale Riding-Type High-Speed Transplanter

This small-scale riding-type high-speed transplanter operates with 4 rows, offering a choice of row spacing between 25/30 centimeters. Plant spacing can be adjusted from 12 to 28 centimeters, and transplanting depth can be varied from 10 to 40 millimeters. With a production rate exceeding 1.5 mu per hour, it is suitable for mechanical transplanting operations in small paddy fields in hilly and mountainous areas.

Figure 5: Small-Scale High-Speed Riding-Type Rice Transplanter

III. Field Management

In rice fields, fertilization and pesticide spraying are preferably performed using multi-rotor drones. The operating width is adjustable from 4 to 11 meters, with a maximum single flight time of approximately 30 minutes. The maximum capacity of the material box is 60 liters, equipped with pressure centrifugal nozzles for uniform atomization. A matching broadcasting system is provided, suitable for spreading granular fertilizers within 0.5 to 10 millimeters, such as urea, compound fertilizers, powders, etc., with a spreading width of up to 8 meters, meeting the operational requirements of different terrains such as hilly fields and mountainous areas.

Unmanned Aerial Vehicle for Crop Protection: A Closer Look

Section Four: Harvesting

In the hilly rice-growing regions, small-scale fully-fed self-propelled track harvesters can be employed for rice harvesting. These machines are capable of completing harvesting, threshing, cleaning, stubble cutting, and bagging in one go. They utilize hydraulic left and right braking for turning, are lightweight, and exhibit excellent maneuverability and off-road capabilities, enabling them to operate smoothly even in environments with a mud depth of up to 300 millimeters. Equipped with secondary cutting knives under the cutting platform, these harvesters can cut stubble low, effectively overcoming surface irregularities or damage from field ridges. With a productivity rate ranging from 0.8 to 1.2 acres per hour, they are well-suited for mechanized harvesting operations in small rice fields in hilly regions. Figure 7: Small Self-Propelled Tracked Harvester