2011 WAEC Agricultural Science Theory (a) (i) Define the term soil tillage. [2 marks]  (ii) Distinguish between primary tillage and secondary tillage….

Explanation

 4(a)(i) Definition of soil tillage Soil tillage is the mechanical manipulation of soil to provide suitable medium for crop growth. OR Soil tillage is the working of the soil with suitable implements to provide a soil medium of fine tilth for crop growth 

(ii) Distinction between primary tillage and secondary tillage 
Primary tillage is the breaking of the soil into big clods with the aid of the plough or other appropriate implement whereas, secondary soil tillage is the pulverizing / breaking of the big soil clods into fine tilth 

(b) Roles of soil management practices 
Roles of green manuring 
It reduces soil erosion 
It adds nutrients to the roil 
-It increases the population of soil micro — organisms/ macro-organisms 
It improves aeration in the soil t improves the soil structure 
-It increases the humus content of soil/C.E.C -
- It improves water infiltration 
-It improves water holding capacity. 
- It buffers the soil/regulates soil pH 

Roles of mulching 
- Maintains a uniform soil temperature 
- Increases water infiltration in the soil 
- Controls weeds 
- Reduces soil erosion 
- Conserves soil moisture
- Increases soil fertility if organic mulch  is used 
- Improves soil structure if organic mulch  is used 

(c) Reasons for carrying out irrigation in crop production 
- Softens the ground for tillage practices 
- Cools the soil arid atmosphere thereby creating more favourable environment for plant growth
- Provides crop insurance against drought/supplements water requirement of crops 
-Provides cool environment for growth of soil organisms
- Can be used to apply fertilizer(Fertigation)
-Makes possible two or more croppings within one year
-Helps in washing out or diluting excess salts in the soil