Sichuan’s rice cultivation spans 1.8667 million hectares, contributing significantly to national grain production. The warm, humid climate facilitates frequent pest outbreaks including rice blast (Magnaporthe oryzae), striped stem borer (Chilo suppressalis), and brown planthopper (Nilaparvata lugens), causing 10-20% annual yield losses. Traditional manual spraying covers only 0.33-0.53 ha/day with uneven distribution, while ground machinery fails in mountainous terrain. Agricultural drones revolutionize this process by covering 20.00-33.33 ha/day with precise chemical application.
The diverse topography creates distinct cultivation zones. The Chengdu Plain (30% of provincial rice area) features large-scale farms (>133 ha) with 80% mechanization. Central hills have fragmented plots (0.33-1.00 ha), and basin mountains contain terraced fields (<0.07 ha) requiring manual labor. Popular varieties like Yixiangyou (20% area) show high yield but rice blast susceptibility, while Chuanyou series (15% area) resists lodging but is vulnerable to sheath blight.
| Topography | Representative Area | Field Characteristics | Suitable Agricultural UAV |
|---|---|---|---|
| Plain | Chengdu Plain | Consolidated fields >133 ha | DJI T40: 30L payload, 5.33-8.00 ha/h coverage |
| Hills | Central Sichuan Hills | Fragmented plots (0.33-1.00 ha) | XAG P100: 4-level wind resistance, 3-8m spray width |
| Mountains | Basin Periphery | Terraces <0.07 ha | Multi-rotor agricultural drones with terrain following |
Seasonal pest dynamics require timed interventions. Tillering stage (May-June) sees sheath blight (10-20% incidence) and stem borer infestations (5-8 larvae/m²). Heading stage (July-August) brings rice blast (15-30% in mountains) and leaf rollers causing 30-40% leaf damage. Regional variations include 10-15% higher rice blast incidence at 800-1,500m elevations and 50-70% sheath blight prevalence in river valleys.
Pre-operational planning for agricultural UAVs involves three critical phases:
1) Equipment Selection: DJI T40 suits plains with 10m spray width and 30min endurance. For complex terrain, XAG P100’s compact design enables navigation through narrow terraces. Calibration ensures <±0.5m positioning accuracy and spray uniformity:
$$ \text{Deposition Uniformity} = \left(1 – \frac{\sigma}{\mu}\right) \times 100\% $$
where \(\sigma\) is droplet density standard deviation and \(\mu\) is mean density.
2) Chemical Formulation: Pesticide selection follows real-time pest monitoring. Critical parameters include:
| Pest | Pesticide | Dilution Ratio | Dosage (mL/ha) | Nozzle Pressure (MPa) |
|---|---|---|---|---|
| Rice Blast | 75% Tricyclazole WP | 1:1,000-1,500 | 1,200-1,500 | 2.5-3.0 |
| Stem Borer | 20% Chlorantraniliprole SC | 1:2,000-3,000 | 150-225 | 2.0-2.5 |
| Sheath Blight | 10% Validamycin AS | 1:500-800 | 2,250-3,000 | 2.0-2.5 |
Chemical calculation example for 10ha stem borer control:
$$ \text{Pesticide Volume} = \text{Dosage} \times \text{Area} = 200 \text{mL/ha} \times 10 \text{ha} = 2,000 \text{mL} $$
3) Mission Planning: Multispectral sensors identify infestation hotspots through NDVI analysis:
$$ \text{NDVI} = \frac{\text{NIR} – \text{Red}}{\text{NIR} + \text{Red}} $$
Flight paths optimize coverage while avoiding obstacles. Strategic planning reduces chemical waste by 10-20% and improves efficiency by 15-25%. For sensor specifications, see nan.
Operational control of agricultural drones requires precise parameter adjustments:
Flight Parameters: Altitude maintains 1.0-2.0m above canopy, lower during early growth. Optimal 1.5m height maximizes leaf deposition. Speed adapts to conditions:
| Condition | Speed (m/s) | Effect |
|---|---|---|
| Standard Operation | 5-8 | Balanced coverage |
| Severe Infestation | 3-5 | Increased deposition |
| Headwind (>3m/s) | Base – (1-2) | Reduces drift <10% |
| Tailwind | Base + (1-2) | Maintains >85% uniformity |
Mathematically:
$$ v_{\text{adj}} = v_{\text{base}} \pm \Delta v \quad \text{where} \quad \Delta v = f(\text{wind speed}) $$
Spray Optimization: Nozzles maintain 90°±5° to rice stems. Real-time monitoring detects nozzle clogs or uneven spray patterns. Environmental constraints include:
- Temperature: 20-30°C (avoid >35°C to prevent volatilization)
- Humidity: 60-80% (reduces evaporation or runoff)
- Wind: <3级 (limits drift)
- Precipitation: No rain within 6h post-application
Implementation of agricultural UAVs in Sichuan’s varied terrain demonstrates 40-60% efficiency gains over manual methods. Properly calibrated systems achieve >90% spray uniformity, significantly reducing chemical usage while maintaining 85-95% pest control efficacy. Future advancements should focus on AI-powered infestation prediction and automated response systems to further optimize resource utilization in sustainable rice production.