(a)(i) Define crop rotation. [2 marks] (ii) Design a four-year crop rotation system using yam, cassava, maize and groundnut. [8 marks] (b) State four reason...

 (a)(i) Define crop rotation. [2 marks] (ii) Design a four-year crop rotation system using yam, cassava, maize and groundnut. [8 marks]

(b) State four reasons why weeds are difficult to control. [4 marks]

(c) Mention 'two effects of diseases on crop production [2 marks]