CEng / IEng / EngTech via IAgrE Precision Agriculture & System Management: practice questions

Question 1 · medium

A farmer uses SBAS corrections for planting and finds that rows planted last season do not line up with this season's guidance lines. The most likely reason is

1. SBAS gives acceptable pass-to-pass accuracy but drifts over time, so its year-to-year repeatability is poor
2. SBAS signals are switched off outside the harvest season, so the receiver reverted to a different datum
3. SBAS corrections are only valid for spraying, and the planter's own sensors reject them after one season
4. SBAS always gives centimetre accuracy, so the planter's row units must have worn and shifted sideways instead

Question 2 · hard

Three years of yield maps are each divided by their own field mean. What is the purpose of this normalisation?

1. To convert all yields to the same standard moisture content before averaging
2. To compare relative performance across seasons with different average yields
3. To remove GNSS errors that differ between the harvest dates of each season
4. To make the three maps additive so that total farm production can be summed

Question 3 · hard

What advantage does pulse-width modulation (PWM) of nozzle solenoids have over pressure-based rate control?

1. Flow varies with the square of the duty cycle, giving a wider range at higher pressure
2. The nozzle orifice is widened electrically, so no solenoid valve is needed at all
3. Pressure is doubled for every step in duty cycle, giving finer control at low rates
4. Flow is varied at nearly constant pressure, so droplet size stays within the nozzle's range

Question 4 · easy

Why is metadata essential when archiving yield and application data?

1. Metadata compress the files so that more seasons fit on one storage device
2. Metadata replace the need to calibrate the sensors in the following season
3. Metadata encrypt the records so that only the equipment maker can read and restore them later
4. Without units, dates, sensor and coordinate system the data cannot be reused later

Question 5 · easy

A farm's application records use 'UAN 32', 'UAN32' and 'urea-AN solution' for the same product across seasons. Which data-quality dimension is poor?

1. Positional accuracy
2. Consistency
3. Timeliness
4. Radiometric resolution

Question 6 · hard

A yield dataset and a soil ECa map of the same field do not overlay; the yield points appear about 1.5 m north of the ECa features everywhere. The most likely cause is

1. A grain-flow delay error in the yield monitor during harvest
2. Random GNSS noise that averages to zero over the whole field
3. A kriging error introduced when the ECa map was interpolated
4. A datum or coordinate-system mismatch

Question 7 · hard

An auto-steer system costs 18,000 currency units, lasts 6 years with no salvage, and the interest rate is 10 %. It saves 15 units per hectare. The break-even area per year is about

1. 200 ha
2. 276 ha
3. 1200 ha
4. 331 ha

Question 8 · medium

A contractor's guidance system has a fixed cost of 3000 currency units per year. Used on 600 ha per year, the fixed cost per hectare is

1. 0.2 units/ha
2. 5.0 units/ha
3. 50 units/ha
4. 18 units/ha

Question 9 · medium

A smallholder region wants the benefits of auto-steer and variable-rate spreading, but farms average under 2 ha. Which delivery model is most realistic?

1. Each farmer buying an RTK base station so that every plot has its own reference
2. Replacing all crops with one crop so that uniform rates become optimal everywhere
3. Waiting until farms merge to over 500 ha before using any precision tools
4. Custom-hiring centres or contractors spreading equipment cost over many farms

Question 10 · hard

An on-farm trial compares variable-rate and uniform nitrogen. Why should the uniform-rate check strips be replicated across the zones rather than placed in one block?

1. So the yield monitor can be calibrated on each strip rather than on weighed loads
2. So fewer passes are needed and the harvest is completed in a shorter time
3. So differences between treatments can be separated from differences between zones and soils
4. So that the uniform strips receive more nitrogen in total than the variable-rate strips beside them