Agricultural Science 3 Nov/Dec 2009

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Agricultural Science Paper 3, Nov/Dec 2009

Questions:		1	2	3	4		Main

General Comments
Weakness/Remedies
Strength

Question 3

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]

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)
Crop	Weeded	Not weeded
Millet	3912	2512
Cassava	7225	3852
Soya bean	3148	1155
Onion	2450	1525

For each of the crops, determine the percentage loss in yield resulting from failure to control weeds. [ 8 marks]
Which of the crops is most affected by weeds? [ 1 mark]
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.
The expected answers include:
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%