Distinguish between the terms renewable and sustainable.

Construct a labelled flow diagram to show the processes that link soil with the following three storages:

The atmosphere
The lithosphere
Living organisms

Annotate each labelled flow with an example of the matter involved.

Evaluate ways in which different agricultural techniques may affect the sustainability of soil as a resource.

“Renewable” resources can be naturally replenished;
“Sustainable” is the use of resources at a rate less than or equal to their replenishment / that allows similar use for future generations;

“Renewable” refers to the resources themselves;
“Sustainable” refers to the activities affecting resources (eg extraction/ exploitation/use);

resources may be “renewable” but their current extraction/exploitation/use may, or may not be “sustainable”;

[1 max] may be awarded for an appropriate example of BOTH a renewable resource (a good or service e.g timber) AND a sustainable practice (e.g. harvesting only natural income);

[2 max] for renewable and [2 max] for sustainable

[4 max]

Award [1 mark] for each correctly labelled process/flow up to [4 max]
Award [1 mark] for each valid example of matter up to [4 max]
Award [5 max] if diagram is unclear/ambiguous

[6 max]

This question is from an exam for a previous syllabus. Part c questions in the current programme are likely to address a far wider breadth of syllabus material.

Use of agrochemicals (technique):
manure or organic fertilisers may help with increasing the fertility of the soil / water retention of the soil (increase sustainability);
use biological control may reduce soil contamination by pesticides(increase sustainability);
artificial fertilisers may toxify the soil if overused (decrease sustainability);
use of pesticides might contaminate /poison soil(decrease sustainability);

Tillage/ploughing method (technique):
contour ploughing may reduce erosion runoff (increase sustainability);
conservation tillage” (chisel / moldboard plough) is a sustainable technique because techniques that do not destroy the soil structure are applied(increase sustainability);
tillage is timed to the season with less rain/wind to reduce erosion(increase sustainability);
gradient ploughing/parallel with slope may increase soil loss through erosion(decrease sustainability);

Reduction of erosion(technique):
undivided/large areas may lead to greater wind erosion of soils(decrease sustainability);
bare land/soil during rains/winter may lead to increased erosion(decrease sustainability);
wind-breaks/hedges may reduce wind erosion(increase sustainability);
growing cover crops or mulching after harvest can reduce soil erosion(increase sustainability);

Cropping technique(technique):
multiple/mixed cropping may help maintain mineral/nutrient composition(increase sustainability);
leaving soil fallow / crop rotation with N-fixing plants may help maintain nutrients(increase sustainability);
use of GM crops to reduce need for fertilizers/water(increase sustainability);
monocropping may lead to loss of nutrients(decrease sustainability);
intensive harvesting may lead to nutrient loss(decrease sustainability);
use of the "wrong" crops / non-native crops that have very high water/nutrients demand from the soil(decrease sustainability);
Small scale slash and burn agriculture when combined with long resting/fallow periods can be sustainable/when fallow period is too short this is unsustainable;

Irrigation(technique):
drip irrigation may reduce leaching/mineral/nutrient loss(increase sustainability);
overuse of irrigation/inappropriate types of irrigation may lead to leaching/nutrient loss salinization of the soil(decrease sustainability);

Livestock/pastoral farming:
rotating fields or letting them rest to avoid overgrazing that could lead accelerated erosion or soil compaction(increase sustainability);
intense or high density grazing leads to accelerated erosion or soil compaction(decrease sustainability);

Award [6 max] if response addresses only increase or only decrease in sustainability.
Award [4 max] if sustainability of the technique is not explained.

Do not award any marks for naming the technique.

[8 max]

Expression of ideas [2 max]

The majority of candidates were able to gain a mark for renewable and sustainable as definitions. But making a clear distinction between the terms was only possible for the stronger candidates.

The guide specifically mentions that candidates should be able to draw diagrams that show the links between the soil, lithosphere, atmosphere and living organisms. The use of the terms systems diagram or flow diagram is not in the guide specifically, though in Topic 1.1.9 candidates are expected to construct models of flows and storages in a system. Very few candidates produced a clear diagram that linked the soil to the other three storages. However most candidates who attempted this question did manage to show the processes that link the storages with an example of the matter involved.

The candidates clearly knew about different agricultural techniques and were mostly able to evaluate these for sustainability to gain a number of marks.