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 Agricultural Science Paper 3, Nov/Dec 2009
 Questions: 1 2 3 4 Main
Weakness/Remedies
Strength

Question 3

1.   A farmer cultivated sorghum at two different sites labelled P and Q as shown in the diagram

below.  The areas covered by the sites were the same.  The farmer observed that yields from site Q were relatively lower than yields from site P.

Study the illustration and use it to answer the questions that follow

(i)    Suggest two possible causes of the poor yields observed on site Q.         [2 marks]
(ii)    List two measures the farmer could adopt to improve yields on site Q.   [2 marks]

1.    A study was conducted to investigate the effects of weeds on the yields of crops.

Results of the study are presented in the table below.

Use the table to answer the questions that follow.

 Crop Yield(kg/ha) Weeded Not weeded Millet 3912 2512 Cassava 7225 3852 Soya bean 3148 1155 Onion 2450 1525
1. For each of the crops, determine the percentage loss in yield resulting from failure to   control weeds.                                                                           [ 8 marks]
2. Which of the crops is most affected by weeds?                        [ 1 mark]
3. Suggest two possible reasons for the loss in yield resulting from failure to control weeds.         [ 2 marks]
_____________________________________________________________________________________________________
OBSERVATION

This question was popular with the candidates.  In 3(a) ( i and ii), majority of the candidates were able to suggest possible causes of the poor yields observed on site Q and list measures the farmer could adopt to improve yields on site Q.
However, in 3b(i), many candidates could not determine the percentage loss in yield resulting from failure to control  weeds.
In 3 (b)(ii and iii), majority of the candidates could state which of the crops is most affected by weeds and suggest possible reasons for the loss in yield resulting from failure to control weeds.
Percentage loss in yields for each crops resulting from failure to control weeds
Yield from weeded plot – yield from plot not weeded  X 100
Yield from plot weeded

Millet
3912 – 2512 x 100
3912                  =     35.79%
Cassava
7225 – 3852  x 100
7225                  =     46. 69%

Soyabean
3148 – 1155 x 100
3148                  =     63.31%

Onion
2450 – 1525 x 100

2450                      =    37.76%