ASRB NET — Farm Machinery & Power / Land & Water Management Engineering / Agricultural Structures & Process Engineering · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersUsing positioning, sensing and variable-rate control to manage fields by the metre instead of by the hectare.
In the exams: ICAR AICE subject 43 Unit 8; elective in the ICAR 6th Deans' Committee B.Tech
ASRB NET — Farm Machinery & Power
Guidance, auto-steer, yield monitors, variable-rate applicators and section control as machine systems; calibration and field-capacity calculations with precision tools.
How our questions for ASRB NET spread across the units of Precision Agriculture & System Management. Difficulty: 28 easy, 27 medium, 3 hard.
| Variable-rate technology | 8 | |
| Yield monitoring | 7 | |
| ISOBUS basics | 7 | |
| Auto-steer and guidance | 6 | |
| Prescription maps | 6 | |
| Proximal and remote sensing for crops | 6 | |
| Section control | 6 | |
| GNSS and RTK positioning | 5 | |
| Farm management information systems | 4 | |
| Farm data management | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
What distinguishes real-time kinematic (RTK) positioning from ordinary code-based GNSS?
C. It resolves carrier-phase ambiguities using data from a nearby base station
RTK uses the carrier phase and corrections from a base at a known point to fix integer ambiguities, giving about 1–2.5 cm. Wide-area geostationary corrections describe SBAS, which gives sub-metre accuracy; averaging code ranges or using Doppler does not reach centimetre level.
Which accuracy class is usually adequate for broadcasting fertiliser with a 24 m spinner spreader?
B. SBAS, sub-metre to about one metre
A wide spinner spreader with overlapping patterns does not benefit from centimetre accuracy; SBAS is usually adequate. RTK is needed for planting, strip tillage and controlled traffic. Uncorrected GNSS is a few metres, not 50 m.
Which guidance pattern suits a field irrigated by a centre pivot?
D. Circle pattern around the pivot centre
Circle patterns follow the concentric wheel tracks of a centre pivot. A straight line crosses the pivot tracks; A-plus-heading is still straight; a spiral from the corner ignores the circular layout.
A sprayer applies 120 L/ha at 10 km/h with nozzles spaced 0.5 m. The flow required from each nozzle is
B. 1.0 L/min
q = rate × speed × spacing / 600 = 120 × 10 × 0.5 / 600 = 1.0 L/min. 10 L/min and 0.1 L/min are factor-of-ten slips in the 600 constant; 2.0 L/min drops the 0.5 m spacing (treats it as 1 m).
In a semivariogram, the range is
B. the distance beyond which sample values are no longer spatially correlated
Range is the correlation distance. Variance at zero distance is the nugget; the plateau is the sill; max minus min is the statistical range of the data, not the semivariogram range.
Why is near-infrared reflectance high from healthy green leaves?
B. Light is scattered at the cell-air boundaries in the spongy mesophyll
Internal scattering in the mesophyll produces the high NIR plateau. Chlorophyll absorbs red and blue, not NIR; water absorption bands lie near 1450 and 1940 nm; the cuticle is not a perfect mirror.
A canopy has NIR reflectance 0.50 and red reflectance 0.08. Its NDVI is about
A. 0.72
NDVI = (0.50 − 0.08)/(0.50 + 0.08) = 0.42/0.58 = 0.72. 0.42 forgets the denominator; 6.25 is the simple ratio NIR/red; 0.84 is 0.42/0.50.
Soil apparent electrical conductivity (ECa) measured by electromagnetic induction in a non-saline field mostly reflects
C. Clay content and soil water, which control water-holding capacity
In non-saline soils ECa is driven mainly by clay and water content, so it maps texture and water-holding capacity. It is not a nitrate sensor, surface organic carbon is not its main driver, and its depth of response is a few metres at most.
Which AEF ISOBUS functionality lets an implement control certain tractor functions, such as speed or hydraulics, under defined safety rules?
D. TIM
Tractor Implement Management (TIM) lets the implement command tractor functions. TC-BAS records totals, AUX is auxiliary control such as a joystick, and UT is the universal (virtual) terminal.
The ISOBUS tractor ECU (ISO 11783-9) mainly
A. passes tractor data such as speed, hitch and PTO status onto the implement bus
The TECU is the gateway between the tractor's internal network and the implement bus, supplying speed, hitch, PTO and other signals. Task data sit with the task controller; implements have their own ECUs; corrections go to the receiver.
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