🌾 Yield Monitoring and Site-Specific Management

Yield maps reveal hidden field variability and are the operational starting point for site-specific crop management decisions.

Yield Monitoring

Yield monitoring is the real-time measurement and mapping of crop yield during harvesting. It generates yield maps — the foundation of precision agriculture.

How Yield Monitors Work

1. Grain flow sensor: Measures the mass of grain entering the combine's clean grain elevator
2. Grain moisture sensor: Measures grain moisture content for standardization
3. GPS receiver: Records geographic coordinates every 1–3 seconds
4. Area sensor: Measures header width and ground speed to calculate harvested area
5. Data logger: Records and stores all data for map generation

Yield Map Interpretation

• High-yield zones: Areas consistently producing above average — maintain current management
• Low-yield zones: Investigate causes — compaction, drainage, nutrient deficiency, pest pressure
• Variable zones: Require targeted management based on limiting factors

Multi-year Yield Maps

• Single-year maps can be misleading (weather effects)
• Overlaying 3–5 years of yield maps reveals stable management zones
• Stable zones are the basis for site-specific management

Site-Specific Crop Management (SSCM)

Concept

SSCM treats different parts of a field differently based on spatial variability, rather than applying uniform management.

Steps in SSCM

1. Characterize Variability

• Soil sampling: Grid sampling (1 sample per hectare) or zone-based sampling
• EC mapping: Electromagnetic induction sensors map soil texture variability
• Elevation mapping: RTK-GPS creates detailed topographic maps
• Remote sensing: Satellite/drone imagery for crop canopy variability

2. Define Management Zones

• Zones with similar soil, terrain, and yield potential grouped together
• Typically 3–5 zones per field
• Use clustering algorithms on multi-layer data (soil, yield, topography)

3. Create Prescription Maps

• Zone-specific input recommendations
• Example: Zone A (sandy, low OM) → 150 kg N/ha; Zone B (clay, high OM) → 100 kg N/ha

4. Apply Variable Rate

• VRT equipment reads prescription map and adjusts input rate automatically
• Seed rate: Higher in productive zones, lower in poor zones
• Fertilizer: Based on zone-specific soil test values
• Lime: Applied only where pH correction needed

Economics of Precision Farming

Break-even: Precision farming pays for itself within 2–3 years for large farms (>5 ha)

Summary Cheat Sheet