ICAR AICE-JRF/SRF (PhD) — Subject 59 Forestry · India · National Testing Agency for ICAR
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 ICAR AICE-JRF/SRF spread across the units of Forest Soils & Soil Conservation. Difficulty: 2 easy, 30 medium, 16 hard.
| Soil classification: USDA Soil Taxonomy and WRB | 7 | |
| Chemical properties: pH, cation exchange, base saturation | 6 | |
| Nutrient cycling in forest ecosystems | 6 | |
| Soil-forming factors and processes under forest | 5 | |
| Forest floor: litter, humus forms (mor, moder, mull) | 5 | |
| Soil and site quality: soil-site relationships | 5 | |
| Forest soil fertility, fertilisation of plantations | 4 | |
| Soil erosion under forest and after disturbance | 4 | |
| Physical properties: texture, structure, bulk density, water holding | 3 | |
| Problem soils: saline, alkaline, lateritic, acid, waterlogged | 2 | |
| Soil conservation measures on forest land | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Why do forest soils that have never been ploughed commonly show sharper horizon boundaries than nearby farmed soils?
C. Ploughing mixes the upper horizons into a uniform layer
Tillage homogenises the topsoil (forming an Ap horizon); unploughed forest soils keep O, A and E horizons distinct, although tree uprooting mixes soil locally.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Annual litterfall is 4 t ha⁻¹ and the steady-state forest floor holds 20 t ha⁻¹. What is Olson's decomposition constant k and the mean residence time?
D. k = 0.2 per year; 5 years
k = litterfall / forest floor mass = 4/20 = 0.2; mean residence = 1/k = 5 years. 15 years is the time for about 95% loss (3/k), not the mean residence.
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 field capacity 25% and wilting point 12% (by mass), bulk density 1.4 g cm⁻³ and rooting depth 50 cm. What is its available water capacity?
A. 91 mm
AWC = (0.25 − 0.12) × 1.4 × 500 mm = 91 mm. 65 mm omits bulk density; 175 mm uses field capacity alone.
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 at pH 4.5 has 100 times more hydrogen ion activity than one at pH:
C. 6.5
Each pH unit is tenfold; two units is 100-fold, so pH 6.5.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Deeply weathered soils with an oxic horizon, low CEC and dominance of kaolinite and oxides under humid tropical forests belong to the order:
D. Oxisols
Oxisols (Ferralsols in WRB). Mollisols are grassland soils; Gelisols have permafrost.
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 Soil Taxonomy name 'Udult', the suffix '-ult' indicates the order Ultisols and 'Ud-' indicates:
A. A humid (udic) moisture regime
Ud- comes from udic, a humid moisture regime; aquic gives Aqu-, aridic Ar-, cryic Cry-.
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
A soil–site equation developed for loblolly pine in one region is applied unchanged to a drier region with different soils. The main risk is:
D. Different limiting factors bias the predictions
Soil–site relations are regional; the relative importance of water, nutrients and depth changes with climate and soils.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Irrigation water contains Na 20, Ca 6 and Mg 2 mmolc L⁻¹. What is its sodium adsorption ratio?
D. 10
SAR = 20 / √((6 + 2)/2) = 20/√4 = 10. 5 divides by (Ca + Mg)/2 without the square root; 2.5 divides by Ca + Mg.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
Using the USLE with R = 300, K = 0.3, LS = 2 and P = 1, what is the annual soil loss for undisturbed forest with C = 0.003 and for the same site after disturbance with C = 0.05?
D. 0.54 and 9 t ha⁻¹
A = 300 × 0.3 × 2 × C: 180 × 0.003 = 0.54; 180 × 0.05 = 9. 180 omits C entirely.
Further reading: See the manual sources: Binkley and Fisher; Brady and Weil; Keys to Soil Taxonomy; WRB 2022; USDA Handbook 60; Likens and Bormann
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