1.         Two roles of humus in the soil that is beneficial to crops                   

-          Provide nutrients

-          Increase water holding capacity

-          Increase soil temperature

-          Neutral soil PH       

2.        Five activities that may be undertaken in organic farming                 

-          Mulching

-          Apply manure

-          Use medicinal plants to control parasites and diseases

-          Crop rotation

-          Rear livestock on natural organically grown pasture

-          Physical/ cultural/ biological/ pests, weeds and disease control

3.        Four effects of temperature on crop growth

-          Low temp-slow growth rate

-          increase incidence of negative infection e.g. CBD

-          improve quality of some crop

-          High temp-cause wilting

-          increase growth rate

-          improve quality of some crops

-          increase pest and disease incidences (1/2x4=2mks)



4.        Four ways by which wind affects the growth of crops.                          

            - Causes physical damage to crops.

            - Cause rapid spread of diseases/ pests/ weeds.

            - Can cause water stress as a result of evaporation.

            - Causes stress of crops due to chilling caused cold winds.

            - Encourage transpiration hence water and mineral uptake.

5.        Two factors related to light that affect crop production and distribution in Kenya:- 

-          Light intensity

-          Light duration

-     Light wavelength

6.        The environmental conditions that may lead to low crop yields                          

-          Poor soil fertility /infertile soil

-          Damage by hailstorms

-          Less rainfall/unreliable/drought

-          Poor soil type resulting into leaching or water logging

-          Inappropriate soil PH

-          Inappropriate temperature (too low or high)

-          Excessive wind leading to increase in water loss from the soil

-          Extreme relative humidity

-          Extreme of light intensity

-          Topography / some attitudes e.g. very high may limit crop growth ( 1mk x any 7pts = 7mks)


8.        One physical characteristic used in classifying soil is:                                                   

-          Colour,

-          Texture,

-          Structure


9.        Four advantages of organic farming                                                 

-          Environmental friendly

-          Products do not have organic farming

-          Products do not have organic chemical residue

-          Improve soil structure

-          Replenishes nutrients in the soil as it uses organic manure

-          Enhances soil water retention

-          Provides food for soil microbes

-          Enhances soil water infiltration ( 4x ½ = 2mks)


11.       Briefly explain how sub-soil as a horizon in a soil profile can affect soil productivity        

- It may have hard pan which interfere with water infiltration                                            


12.      (a) What are the three aspects of light that are important to a farmer?  

-          Light duration                                                                                            

-          Light intensity

-          Light wave length                                                                           

15.      a) State merits of horizon A

-          source of plant  nutrients

-          support/anchor  the crops

-          store of water for the crops

-          sources of soil micro organism


b) State distinct features of horizon B                                                                                                           

-          deficient of humus(nutrients)

-          contain leached nutrients

-          contains more compact soil particles

-          presence of hard pans in  some soils

c)   What does the term transition zone refer to in soil profile                                                         

-          Transitional zone-this is a zone bordering two adjacent layer of soil profile

d) Name horizon C and state its importance                                                                                           


Weathered rock


-          Give  rise  to sub soil

-          Source of minerals

-          Determine mineral content  of  soil and type  of soil


16        Outline two ways temperature affects crop production

-          Low temperatures encourages crop diseases such as leaf rust

-          Low temperatures may increase or lower the quality of farm produce

-          High temperatures hastens maturity/ improves the quality/ lower the quality

-          Increases the rate of evapo transpiration which may result loss plant moisture/ leading to wilting of crops

17.        List four ways by which biological agents can enhance the process of soil formation                                                                                                  

-          Movement of animals in large numbers

-          Decomposition of plant and animal remains by soil micro- organisms

-          Physical breaking of rocks by roots of higher plants

-          Man’s activities e.g. cultivation, mining and road construction

-          Mixing up of soil by animals e.g. earth worms and


18.      List four environmental factors that affect crop production in Kenya


-          Temperature/ Altitude                                                                             

-          Soil type;

-          Prevailing winds;

-          Rainfall;         (4x ½ =2mks)


19.      Explain the role played by topography in soil formation


-          It influences the movement of the weathered materials hence affecting the depth of soil development;                                                                                                                            


Download and print these questions from here