This question was fairly attempted by the candidates.  In 4(a), majority of the candidates were able to list the edaphic factors that influence crop growth.  However, majority of the candidates could not explain gravitational and hygroscopic water as used in soil and water conservation as required in 4(b)i-ii.  Majority of the candidates were able to state the deficiency symptoms of nitrogen, phosphorus and potassium in crops but most of them couldn’t  state the benefits derived from draining farmlands as required in 4c(i-iii) and 4(d), respectively.
The expected answers include:
(b)(i)    Gravitational water
             This is the excess water above field capacity that drains out of the soil under the influence of gravity. This type of water is unavailable for plant use
                                              OR
           This is the water held in soil macro pores that drains out under the influence of gravity.Thistype of water is unavailable for plant use
(c)     Hygroscopic water
This is the water present in an air-dried soil held tightly by soil solids.  This type of
water cannot be removed by evaporation and roots of higher plants.  It is water
unavailableforplant use
(d)    Benefits derived from draining farmlands
         -   Facilitates planting
         -   Makes tillage operations easy
         -   Improves soil aeration
         -   Improves soil temperature
         -   Allows for cultural practices on the land
         -   Favours the growth of aerobic soil organisms
         -   Means of reclaiming land for agricultural purposes/makes more land available for
             cultivation
         -   Helps to flush excess salts from soils
         -   Enhances seed germination
         -   Increases the depth of the root zone in the soil.
         -   Decomposition of plant and animal residues is increased
         -   Improves soil structure
         -   Increases soil productivity