(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...
Question 1 Report
(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]
Answer Details
(a)(i) Definition of crop rotation
Crop rotation is the practice of growing different types of crops in a planned and definite sequence on the same piece of land over successive cropping seasons or years, in order to maintain soil fertility and reduce the build-up of pests and diseases.
(a)(ii) A four-year crop rotation using yam, cassava, maize and groundnut
The land is divided into four plots so that every crop is grown each year, and each plot carries a different crop in turn. The legume (groundnut) is placed to restore nitrogen, and the heavy-feeding root crops are separated.
| Year | Plot A | Plot B | Plot C | Plot D |
|---|---|---|---|---|
| 1 | Yam | Maize | Cassava | Groundnut |
| 2 | Maize | Cassava | Groundnut | Yam |
| 3 | Cassava | Groundnut | Yam | Maize |
| 4 | Groundnut | Yam | Maize | Cassava |
Note: Groundnut, a legume, is always followed by the heavy-feeding yam so that the nitrogen it fixes is used by the next crop.
(b) Four reasons why weeds are difficult to control
- They produce very large numbers of seeds within a short time.
- Their seeds can remain dormant but viable in the soil for many years.
- They have efficient means of seed dispersal (wind, water, animals).
- Many reproduce vegetatively from rhizomes, stolons and tubers even after the tops are removed.
(c) Two effects of diseases on crop production
- They reduce the yield and quality of the crop produce.
- They may kill the plants or increase the cost of production through control measures.
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