ICAR AICE-JRF/SRF Agroecology: Principles & Practice: practice questions

1 · Agroecosystem structure and function · medium

About what share of energy is commonly quoted as passing from one trophic level to the next in food chains?

1. Roughly one half, with little variation between systems
2. Almost all of it, since energy is conserved in food chains
3. Less than one thousandth in every known ecosystem
4. Roughly one tenth, though actual values vary widely

2 · Agroecosystem structure and function · medium

Natural pest control on a field often depends more on the amount of semi-natural habitat within a few kilometres than on anything done in the field. This illustrates that:

1. Field-level practices have no effect on pests, so only national policy can change pest numbers
2. Processes act at different hierarchy levels, so some must be managed at the landscape level
3. Natural enemies never move between fields, so landscape features are irrelevant to them
4. Pest control is a purely chemical process that does not depend on habitat at any scale

3 · Diversity, complementarity and synergy on the farm · hard

A sorghum-pigeonpea intercrop gives 1.8 t/ha sorghum and 0.6 t/ha pigeonpea. Sole yields are 4.0 t/ha and 1.2 t/ha. What does the LER show?

1. LER = 0.95, so sole crops would need slightly less land than the intercrop
2. LER = 2.40, so the intercrop uses land more than twice as efficiently
3. LER = 0.45, so only the sorghum yield needs to be considered
4. LER = 1.95, so the intercrop saves almost half of the land needed

4 · Diversity, complementarity and synergy on the farm · hard

According to Vandermeer's competitive production principle, an intercrop overyields when:

1. Interspecific interference is stronger than intraspecific interference
2. Both crops have exactly the same rooting depth and growth period
3. Interspecific interference is weaker than intraspecific interference
4. The intercrop is sown at double the density of each sole crop

5 · Diversity, complementarity and synergy on the farm · hard

A field margin contains three plant species with relative abundances 0.4, 0.4 and 0.2. Using the natural logarithm, the Shannon diversity index H' is about:

1. 0.64
2. 1.52
3. 1.05
4. 0.46

6 · Nutrient cycling and recycling within farms · medium

Which crop family does NOT form associations with arbuscular mycorrhizal fungi, so that a preceding crop from it can reduce mycorrhizal colonisation of the next crop?

1. Grasses such as maize, wheat, rice and sorghum
2. Legumes such as soybean, pea and lentil
3. Brassicas such as cabbage and mustard
4. Alliums such as onion, garlic and leek

7 · Traditional farming systems and indigenous knowledge · easy

FAO's Globally Important Agricultural Heritage Systems (GIAHS) programme was launched in:

1. 1972
2. 2002
3. 1992
4. 2015

8 · Traditional farming systems and indigenous knowledge · medium

Waru waru raised fields around Lake Titicaca alternate raised beds with water-filled canals. A key benefit is that the canals:

1. Allow fish to be harvested as the main product instead of potatoes
2. Moderate night frost by storing heat during the day and releasing it at night
3. Remove all salts from the soil so that rice can be grown at high altitude
4. Prevent any rain from reaching the beds during the wet season

9 · Traditional farming systems and indigenous knowledge · medium

Why does shifting cultivation (such as jhum in north-east India) often become unsustainable as population density rises?

1. Shifting cultivation needs synthetic fertiliser, which becomes too expensive as population rises
2. Longer fallows encourage pests that destroy crops in densely populated areas
3. Population growth makes the climate wetter, so burning becomes impossible
4. Fallows are shortened, so soil fertility and vegetation do not recover between cycles