What is soil structure?

KCSE Geography Paper 1 2017 Section B Question 10.

​(a) (i) What is soil structure? 

• Soil structure is the way the individual soil particles are arranged into aggregate compound particles.

(ii) Explain how the following factors influence soil formation.
. Time 
. Parent rock 

Time

•  Where soil formation process takes a short duration, the soils are generally immature/where the process has taken a long period of time, soils are generally well developed mature.

Parent rock

•  The nature of rock influences the rate of weathering in that soft rocks weather fast, while hard rocks are resistant and weather slowly.
•  The parent rock determines the soil texture in that, large/course grained rocks produce large/course grained soils/small fine grained rocks produce small fine grained soils..
•  The type of minerals in the parent rock are transferred to the soil during formation.

(b) Describe the following properties of soil.
. Soil texture 
. Soil porosity 
. Soil colour 

Soil texture

•  This is the degree of fineness or coarseness of the particles making up the soil.
•  It is the size of the soil particles.
•  The texture controls the size and spacing of the soil pores.
•  This effects the soil water content/the drainage/leaching/soil aeration

Soil Porosity

•  This is the amount of pore spaces in the soil.
•  The size of the pore spaces determine the water flowing in the soul sandy soils have high porosity hence allow water to pass through.
•  Clay soils have few pores hence retain water.

Soil colour

•  The soil have different colours influenced by parent rock/vegetation leaching processes.
•  Black/dark brown soils denote a lot of humus.
• Grey soils are characteristics of poorly drained/water logged soils.
•  Whitish soils show high concentration of salts.
•  Reddish soils have high concentration of iron.

​(c) State four negative effects of soil erosion.

•  It leads to loss of productive top soil.
•  It causes uprooting/blowing away of plants/plants are washed away/buried.
•  It can cause destruction of buildings/bridges.
•  Gully erosion exposes underground water lowering the water table.
• It leads to destruction of vegetation cover which can cause desertification.
•  It causes deposition of sediments into water reservoirs.
•  Contaminated sediments deposited into water bodies lead to water pollution,
•  Sediments brought by water erosion to the beaches may make them muddy.
•  It causes land dereliction.

​(d) You are planning to carry out a field study on soil around your school.

​(i) State four preparations that you will make for the study. 

• Setting up objectives/hypothesis
•  Getting permission from the school authority.
•  Making reconnaissance/Pre-visit
•  Assembling various tools/equipment to use.
• Preparing a working schedule.
•  identifying methods of data collection.
•  Literature review

(ii) Give reasons why it is important to study soils through field study.

•  It enables collection of samples for future reference.
•  It enables one to get firsthand information/have easy recall.
• It makes learning real/meaningful.
•  it helps the learners to understand better the theoretical concepts taught in class/teaching becomes easier for the teacher.
•  it helps students develop skills of data collection/soil conservation.
•  It makes learning interesting.

​Related Geography Searches on Soils Form 3 Level

Read More