This question was not popular among the candidates. In 10(a), majority of the candidates could not state the law of diminishing returns correctly.  Also, most of the candidates could neither use the table to draw an input-output graph nor explain the relationships between fertilizer input and sorghum yield as required in 10(b)(i-ii).

Although, most of the candidates were able to enumerate four functions of an agricultural extension agent as required in 10(c), majority of them could not state five benefits of commodity boards in the marketing of agricultural produce in West Africa as required in 10(d).

The expected answers include:
10(a)    Law of diminishing returns in agricultural production
The law states that as successive amounts of a variable factor are applied to one or more fixed factors, output might increase a lot at first but there comes a point at which the use of one more amount of the variable factor will add less to output than the preceding amount.

(b)(i) Input and Output graph of the relationship between fertilizer input and sorghum yield
 

   (ii)     Explanation of the relationships between fertilizer input and sorghum yield
As successive amounts of fertilizer are applied, sorghum yield increase proportionately until it got to a point at which the use of more amount of fertilizer added leads to less yield of sorghum than the preceding amount.

(d) Benefits of commodity boards in the marketing of agricultural produce in West Africa

• Provide ready market for various agricultural commodities
• Help to eliminate the range of differences in prices between farmers and consumers
• Prepare farmers’ mind for what is due to them financially by announcing guarantee prices of their commodities
• Help to increase volume of production by farmers
• Offer technical advice to farmers on the use of farm inputs, etc.
• The pricing policies of commodity (marketing) boards make farmers income stable
• Provide transportation services which help in evacuation of farm produce
• Save farmers the rigour of exporting their produce
• Perform marketing functions and services such as processing, storage, transportation, grading and packaging
• Sometimes settle disputes among farmers
• Grant scholarships to farmers’ children
• Provide credits and subsidies to farmers
• Provide inputs to farmers.