(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]
Explanation
(a)(i) Definition of crop rotation: Crop rotation is the planting of different types of crops on the same piece of land in a definite sequence. (ii) Design of a 4-year crop rotation system using yam, cassava, maize and Groundnut.
| 1st plot | 2nd plot | 3rd plot | 4th plot | |
| 1st year | Yam | Groundnut | Cassava | Maize |
| 2nd year | Groundnut | Cassava | Maize | Yam |
| 3rd year | Cassava | Maize | Yam | Groundnut |
| 4th year | Maize | Yam | Groundnut | Cassava |
NB: – For the purpose of the 4 crops given:
– Yam and cassava must not follow each other
– Groundnut and maize must not follow each other
(b) Reasons why weeds are difficult to control
– Weeds are aggressive and persistent in their growth/vigorous growth
– Weeds have high reproductive capacity
– Most weed seeds have long periods of viability
-Weeds have efficient dispersal methods
– Weeds have efficient means of propagation
-Weed seeds have long period of dormancy
-Some we seeds mature at the same time as the crops and are harvested and stored along with the crops Waiting for the next cropping season (
-Weeds have modified parts, leaves, stems, roots and seeds that help them survive very adverse environmental conditions/wide adaptation
– Most weeds produce many seeds/are prolific
-Short life cycle
(c) Effects of diseases on crop production
Reduction in yield/productivity, Increases the cost of production, Reduction in quality of crops, Causes death -of whole plants, Leads to retarded growth in crops, -Delayed maturity, Causes reduction in the income of the farmers, Damage to crop parts/reduction in photosynthesis