The diagram below illustrates an experimental set-up on soil. Study it and answer the questions that follow.
a) (i) State the aim of the experiment. (ii)Name the parts labelled I and II in the diagram.
b) Describe how the experiment is carried out.
c) State four properties of sandy soils.
d) Describe a test for soil acidity using litmus paper.
Explanation
(a)(i) Aim of the experiment
Separation of soil into its fractions/determination of soil texture by sedimentation
(ii)Naming of the parts labelled I and II
I – Clay in suspension/Clay
II – Silt
(b)Description of the experiment
Place a glass jar on a surface Weigh about 70 – 100g of the soil Add the weighed soil into an equivalent quantity of water in a glass jar Add suitable dispersing agent e,g, NaOH, NaHCO3 Shake the glass jar vigorously to disperse any soil clods Allow the glass jar to settle for an hour Observe the result
(c)Properties of sandy soils
Low cation exchange capacity Diameter is between 0.02 mm – 2m2 Well drained, loose and highly aerated Low plant nutrients Low buffering capacity Leaching of nutrients is high/supports leaching Easily gets hot and cold Low water holding capacity Particles are light and easy to till Gritty/rough/coarse in nature High percolation rate Low capillary action Cannot be moulded
(d)Testing soil acidity using litmus paper
Mix the soil very well Moisten with distilled water Dip red and blue litmus paper into moistened soil If blue litmus paper changes pink/red, the soil is acidic If red litmus paper changes blue, the soil is basic/alkaline If there is no colour change, the soil is neutral
