Unit notes and practice questions
Everything here is for unit 14 of the Grade 12 Agriculture textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
The cards filed under this chapter on the Grade 12 Agriculture page. Open one at a time.
When you use it
Use when calculating the dry mass of soil contained within a specific total volume.
Watch out
Total volume includes both the solid soil particles and the pore space between them.
Drafted from Grade 12 Agriculture, pages 257-267, then checked twice before it went up
When you use it
Use when categorizing soil parameters into physical traits or chemical traits.
Watch out
Bulk density, consistency, porosity, texture, and structure are physical properties, whereas cation exchange capacity and pH are chemical properties.
Drafted from Grade 12 Agriculture, pages 257-267, then checked twice before it went up
| Practice | Structure Type | Key Characteristic |
|---|---|---|
| Bench terrace | Physical | Steps with horizontal cultivated beds and steep risers |
| Fanya-juu | Physical | Embankment along contour with a basin at the lower side |
| Grass strip | Agronomic | Ribbon-like band of grass along the contour |
| Area enclosure | Agronomic | Exclusion of grazing for 2 to 3 years until 50% grass cover |
When you use it
Use to distinguish between physical structures and agronomic management practices for erosion control.
Watch out
In Fanya-juu terraces, soil is thrown uphill from the lower ditch, which gives the structure its name.
Drafted from Grade 12 Agriculture, pages 257-267, then checked twice before it went up
| Soil Separate | Particle Size Range | Matrix Role |
|---|---|---|
| Sand | Inactive | |
| Silt | Inactive | |
| Clay | Active |
When you use it
Use when classifying soil particles by diameter or identifying which fractions contribute to water and nutrient retention.
Watch out
Sand and silt are considered inactive because they do not contribute to the soil capacity to hold water and nutrients.
Drafted from Grade 12 Agriculture, pages 257-267, then checked twice before it went up
When you use it
Use when listing or applying the core agronomic practices required for conservation farming and biodiversity protection.
Watch out
Conservation farming requires all three principles: minimum soil disturbance, crop residue management or cover crops, and crop rotation.
Drafted from Grade 12 Agriculture, pages 257-267, then checked twice before it went up
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
What agroforestry practice involves growing perennial, usually leguminous trees or shrubs in wide rows with an arable food crop planted in between?
Answer: A Alley cropping
Why
Alley cropping (also known as hedgerow intercropping) is the practice of planting annual crops in the spaces or alleys between rows of perennial trees or shrubs.
Question 2
What is another common name for boundary planting in agroforestry?
Answer: B Living fences
Why
Boundary planting is often referred to as living fences or barrier planting because it involves planting trees along property lines, fields, or road edges.
Question 3
An agroforestry system that combines tree growing with livestock production on pasture is called a:
Answer: A Silvopastoral system
Why
Silvopastoral systems combine tree growing with the production of livestock on pasture land.
Question 4
Which agroforestry system is defined as a combination of crops and trees, such as alley cropping or home gardens?
Answer: B Agrisilvicultural system
Why
Agrisilvicultural systems are combinations of crops and trees, such as home gardens and alley cropping.
Question 5
What is the primary purpose of windbreakers and shelterbelts in an agroforestry system?
Answer: B To control wind erosion and lessen evaporation and transpiration
Why
The main purpose of windbreakers and shelterbelts is to control wind erosion. When wind speed is reduced, evaporation and transpiration are also lessened.
Question 6
In tree management, why is the crown of a tree cut at least 2 m above the ground during pollarding?
Answer: B To put new resprouting shoots beyond the reach of cattle
Why
Pollarding cuts the crown at least 2 meters above ground level so that new resprouting shoots are out of reach of browsing livestock.
Question 7
Which aboveground tree management practice involves cutting the tree down to the stump and allowing it to re-grow to maximize biomass production?
Answer: A Coppicing
Why
Coppicing is the practice of cutting a tree down to its stump and allowing it to re-grow in order to maximize biomass production.
Question 8
How is tree root pruning usually carried out to reduce belowground competition between trees and crops?
Answer: C By way of trenching
Why
Root pruning is usually performed by trenching, which separates the root systems of trees and crops to reduce competition for water and nutrients.
Question 9
Which tree species is specifically highlighted in the textbook as being cultivated for fuel wood and charcoal production?
Answer: A <em>Acacia mearnsii</em>
Why
The textbook specifically lists Acacia mearnsii as an example of a fuel wood tree used for fuel wood and charcoal.
Question 10
What is a defining characteristic of an Agro-Silvo-pastoral system?
Answer: B It is a three-way mixture combining crops, trees, and animals
Why
An Agro-Silvo-pastoral system involves a three-way mixture combining crops, trees, and livestock, and can be sustainable even in harsh environments.
The app holds 24 questions on this unit, marked as you go. These are the first 10.
Unit 14 runs from page 251 to page 263 of the Ministry of Education edition.
Ministry of Education edition, English, 302 pages
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