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Management

Optimum resource utilisation

Optimum resource use means getting a good yield without spending the soil, the water, the veld or the money the farm needs next year.

CAPS

Grade 11 · Agricultural Sciences · Management

Agricultural Sciences splits animals from plants, soil and management.

  • The papers

    Paper 1 is animal nutrition, animal production, reproduction and protection. Paper 2 is soil science, plant studies, and agricultural management. Each paper is 150 marks.

  • How to write it

    Use the farming term, then the reason: a deficient mineral, a symptom, a management practice, and why it changes the yield or the health of the animal. A list with no cause does not explain.

  • How a marker reads it

    A common mix-up is “if some is good, more is better”, in fertiliser, water and livestock.

Data-response questions want you to read the table first. A general paragraph about farming that ignores the numbers scores as if you did not see them.

Diagram

Worked theory

Worked theory. A maize land and a bag of fertiliser. The first bags raise the yield a lot. Later bags raise it a little. The last bag costs more than the extra bags of maize are worth, and the unused nitrogen leaves in the rain. The optimum was the earlier bag. The same curve exists for cattle on a camp: one more ox past the grass supply costs more in lick and in damage than it earns. A farmer who chases the maximum harvest in a good year can destroy the resource that would have given a decent harvest in a bad one.

More worked examples

  • The fifth bag of fertiliser

    On a maize trial, bag 1 raises yield by 1.2 tonnes. Bag 2 adds 0.6. Bag 3 adds 0.2. Bag 4 adds almost nothing and costs more than the extra maize is worth. Bag 5 is pure loss, and the unused nitrogen leaves in the next rain. The optimum was around bag 2 or 3, not the largest number on the scale. The same shape appears when a sixteenth cow walks onto a camp that could feed fifteen.

  • Water at noon

    An hour of sprinkler irrigation at noon in January loses a large share to evaporation before it reaches the roots. The same hour at dawn enters the soil. The crop did not need “more hours”. It needed the hour that arrives. Past that, extra water waterlogs the roots and costs diesel. The optimum is the useful hour, not the longest tap. The same shape as the extra bag of fertiliser, on a different input.

In ordinary words

Every input has a best range. Too little fertiliser wastes the rain. Too much burns the crop and washes into the river. Too many animals look like more calves until the veld crosses its carrying capacity. Irrigation past field capacity just drains. Records of rainfall, yield and costs show where the extra unit of input stopped paying. Optimum is not maximum.

In South Africa

A fertiliser trial on the school plot, yield against bags, draws this curve.

Part 1 / 4

What it is

Optimum resource use means getting a good yield without spending the soil, the water, the veld or the money the farm needs next year.

More worked examples

Board walkthroughs on this topic. Open one, copy the working, then try the next.

Example 1 / 20

A farm has a capital investment of R2 000 000 and makes a net profit of R160 000. Calculate the return on investment.

How we got there

Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.

Explain in another language · 11

1. What is the question asking?

Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A farm has a capital investment of R2 000 000 and makes a net profit of R160 000. Calculate the return on investment.

Before any working — hunt first

Given

Numbers and units already in the sentence: R2 · 000 · 000 and · R160 · 000. Copy each one into a column. A name without a number is not given.

Missing

After you copy the given, the letter that still has no number is missing. The paper is pointing at: the return on investment. Circle that word — that is the missing variable.

Find

We are required to find: the return on investment. Write that as a symbol on the left, with a question mark, before you touch a formula.

Calculate

What we need to calculate: ROI = profitcapital × 100. Then substitute the given, one line at a time, to get the return on investment.

In other words — as if you have never seen this before

If you have never seen this before: ROI = profitcapital × 100. We will name a method in words, write the formula with no numbers, then substitute one line at a time.

2. What do we already know?

Profit R160 000; capital R2 000 000.

3. Which method — and why this one?

ROI = profitcapital × 100.

4. Step-by-step working

  1. 01 / 08

    Step A — Read the question twice

    Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  2. 02 / 08

    Step A2 — Hunt: Given, Missing, Find, Calculate

    Given: Numbers and units already in the sentence: R2 · 000 · 000 and · R160 · 000. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: the return on investment. Circle that word — that is the missing variable. Find: We are required to find: the return on investment. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: ROI = profitcapital × 100. Then substitute the given, one line at a time, to get the return on investment.

    Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).

  3. 03 / 08

    Step B — Write the given in a column

    Profit R160 000; capital R2 000 000.

    Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.

  4. 04 / 08

    Step C — Name the method in words

    ROI = profitcapital × 100.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  5. 05 / 08

    Divide

    160 0002 000 000×100=8%.

    Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.

  6. 06 / 08

    Step G — Sense-check the size

    Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.

    Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.

  7. 07 / 08

    Step F — Box the answer with its unit

    8%.

    Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.

  8. 08 / 08

    Step H — What the marker is looking for

    On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.

    Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.

5. The answer

8%.

Copy onto your answer sheet — in this order

Answer: 8%.

6. Check it like a marker

Compare with interest from a bank.

7. A trap first-timers fall into

First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”

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