Exam essay 2 (soil)

Question 1

Defra (2010)

Answer 1

UK soils stores over 10 billion tonnes of carbon in 2010

Question 2

Pimental and Pimental (2006)

Answer 2

Soils store 90% of the water used in agriculture.

97% of available freshwater passes through soil into groundwater.

Question 3

Yang et al (2003)

Answer 3

33% of worlds arable topsoil lost in the last 40 years

Question 4

Kucharick et al (2001)

Answer 4

Estimated that US soils have lost between 30-50% of the soil organic carbon that they contained prior to the establishment of agriculture there.

Question 5

Emmet et al (2010)

Answer 5

Tillage compromises soil functioning (nutrient and water holding capacity) which limits crop yield and vulnerabilities to drought.

Question 6

Wilson et al (2009)

Answer 6

Mycorrhizal hyphae length is correlated with an increased aggregate formation and carbon storage.

Question 7

Edwards and lofty (1982)

Answer 7

Ploughing can reduce earthworm populations which are needed for soil water storage and to improve soil structure.

Question 8

Holland (2004)

Answer 8

Increase in soil organic matter raises carbon sequestration levels while the richer soil biota can also improve nutrient recycling and may also help combat crop pests and disease.

Question 9

Baumhardt (2015)

Answer 9

In Canada, the transition to no til helped reduce rates of very high soil eriosion.

Question 10

Towsend et al (2016)

Answer 10

In the UK there is still 60% conventional tillage, mainly due to economics as early years of no till leads to reduced yields and increased costs of fertilisers.

Question 11

Johnston et al (2017)

Answer 11

Leys improve soil structure and therefore increase soil organic carbon.

Question 12

van Ruijven and Berendse (2005)

Answer 12

The use of legumes in crop rotations by farmers increase nutrient acquisition in soils as they introduce new fixed nitrogen through symbiosis.

Question 13

Rillig et al (2002)

Answer 13

Mycorrhiza fungi increase soil organic matter of surface soil, increase populations of earthworms and improve drainage and macropore flows, reducing the risk of flooding and soil erosion.

Question 14

Dewar (2017)

Answer 14

Heavy rotations of crops eg wheat/wheat/rape deplete the soil of nutrients, while also decreasing the soil structure quality and exposing crops to pest and disease pressures.

Question 15

Tang et al (2003)

Answer 15

Acidic soils have a low content of base cations (Ca, Al) this toxicity affects root growth and the absorption of water and nutrients by plants, causing a reduction in yield.

Question 16

Anda et al (2013)

Answer 16

(Adding Ca rich volcanic dust) Increased growth and reduced aluminium toxicity of cocoa in oxisol soils.

Question 17

Barry (1997)

Answer 17

Soil is the great connector of lives, the source of and destination of all

Question 18

Miles, 1985

Answer 18

Soil acidification results in loss of species diversity.