Indian Forest Service Examination (IFoS) — Forestry optional · India · Union Public Service Commission
Original practice questions written to the published syllabus · not past papersSoil formation under forest, the forest floor, soil classification and site quality, nutrient cycling, and conserving and reclaiming forest and degraded soils.
In the exams: IFoS Forestry Paper I Section B (forest soils, soil conservation and watershed management); ICAR AIEEA-PG Group 09 (forest soils, classification and conservation); ICAR AICE-JRF 59 Unit 8
How our questions for Indian Forest Service Examination spread across the units of Forest Soils & Soil Conservation. Difficulty: 3 easy, 9 medium, 6 hard.
| Problem soils: saline, alkaline, lateritic, acid, waterlogged | 4 | |
| Soil conservation measures on forest land | 3 | |
| Soil-forming factors and processes under forest | 2 | |
| Chemical properties: pH, cation exchange, base saturation | 2 | |
| Soil classification: USDA Soil Taxonomy and WRB | 2 | |
| Soil erosion under forest and after disturbance | 2 | |
| Physical properties: texture, structure, bulk density, water holding | 1 | |
| Nutrient cycling in forest ecosystems | 1 | |
| Soil and site quality: soil-site relationships | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A bleached, ash-grey E horizon over a dark reddish B horizon enriched in iron, aluminium and humus is typical of:
A. Podzolisation
Organic acids from acid litter mobilise Fe and Al from the E and deposit them in the spodic B. Laterisation leaves Fe and Al oxides throughout a red profile.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
A soil has 2.0% organic carbon, bulk density 1.3 g cm⁻³ and no coarse fragments. What is its organic carbon stock in the top 30 cm?
B. 78 t C ha⁻¹
Stock = OC% × BD × depth (cm) = 2.0 × 1.3 × 30 = 78 t C ha⁻¹. 60 omits bulk density; 7.8 and 780 are factor-of-ten slips.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
How many soil orders are recognised in USDA Soil Taxonomy?
A. 12
Twelve orders; 32 is the number of WRB Reference Soil Groups; 6 is the number of categories in the hierarchy.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
In WRB, a saline soil and a sodic soil are classified respectively as:
D. Solonchak and Solonetz
Solonchaks have a salic horizon (salts); Solonetz have a natric horizon (sodium).
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
In the Hubbard Brook experiment, a catchment was clear-cut and regrowth suppressed with herbicide. What happened to stream nitrate?
B. It rose many-fold
Uptake stopped while mineralisation and nitrification continued, so nitrate leached in large amounts.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Which statement about site quality under management is correct?
B. Management degrades or improves it
Site quality reflects soil condition as well as climate; compaction, topsoil loss and nutrient removal degrade it.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
A soil has exchangeable sodium 3 cmolc kg⁻¹ and CEC 12 cmolc kg⁻¹. What is its ESP?
A. 25%
ESP = 3/12 × 100 = 25%, above the sodic threshold of 15. 4% inverts the ratio as a fraction.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
What is the standard amendment for reclaiming sodic soils before planting?
C. Gypsum, followed by leaching
Gypsum supplies calcium to replace exchangeable sodium, which is then leached; saline soils need only leaching and drainage.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
In managed forests, the largest sources of sediment are usually:
D. Roads, landings and skid trails
Compacted, bare, drained surfaces concentrate flow and deliver sediment to streams at crossings.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Which processes are NOT estimated by the Universal Soil Loss Equation?
D. Gully erosion and landslides
USLE predicts average sheet and rill erosion; gullies, mass movement and sediment delivery need other methods.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Ten here, 18 in the app. The Laisha app has every practice question we have written to Indian Forest Service Examination in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
Free for ten days, then one subscription of US$10 a month. We would rather say so here than have you find it later.
An AI operating system for agriculture: free guides, manuals and tools written for every country.