Primary School Agriculture: Volume I: Pedagogy (GTZ, 1985, 144 p.)
 Part III: Examples for practical use
 1. Teaching sub-units
 1.1 The maize harvest-integrating work, observation and classroom teaching 1.2 Surveying farm plots - the use of the plane table 1.3 Results of an experiment on pineapple farming 1.4 Observing the growth of yams 1.5 Planning maize farming

### 1.3 Results of an experiment on pineapple farming

This sub-unit gives the details of how to evaluate an experiment. It does so sticking very closely to one example. But the general procedure is the same for all experiments.

The example is drawn from Mudeka Government School. Under the guidance of IPAR-Buea, the school grew a large number of pineapples on an area of 60 m x 56 m = 3 360 m². Two different planting methods were used. On part of the farm, pineapples are 1.8 m apart from each other in each direction. This is called single row planting. On another part of the farm, pineapples are planted in double rows, staggered, the distance of the plants in each of the double rows is 60 cm, the two rows forming one double row are 60 cm apart, and the centre line of one double row is 2.4 m apart from the centre of the next one. This is called double row planting.

The Problem
Which of the planting methods is superior, and should therefore be recommended to farmers? How can this question be answered?

One important yardstick certainly is the yield, to be got following either method. Two questions might be asked in this respect:

- Which planting method produces higher yields per area?

- Which planting method produces a higher return over costs (i.e. the money initially spent to plant the crop)?The problem is made difficult by the fact that pineapples are a perennial crop. Unlike coffee or cocoa, the time between planting and first harvest, and between first harvest and the first ratoon crop can vary a lot so that there is no clear-cut, short, well-determined peak harvesting time. The procedure proposed provides an assessment of the harvest at the time of measurement and an estimate of future harvests It is best done towards the end of the first heavy harvest. The answer to our problem will be provided by two comparisons:

- yield per standard area: No. of fruits harvested per square meter under single row planting and under double row planting;

- return over costs: Value of fruits harvested at time of measurement compared with cost of planting material for single row planting and for double row planting.

Planting Methods Used in the Experiment

1. Objectives Concerning Farm Work
none

2. Objectives in Agriculture

- Pupils know that in the case of single cropping, planting distances can be smaller and plant populations higher than in the case of multiple cropping.

- Pupils know the practical use of the concept of plant population per hectare.

- Pupils know simple indicators or measures of profitability.

3. Skill Development

a) Study Skills

- Pupils are able to find out the results of a simple experiment.
- Pupils are able to count relatively large numbers of objects exactly.
- Pupils are able to make simple estimates
- e.g. forecasting next year's crop, forecasting price movements for a given crop.

b) Social Skills

- Pupils are able to work in teams of two to three children during outdoor and classroom activities.

A. Introductory Lesson

Objectives
- Pupils know the purpose of the teaching unit.
- Pupils are able to recall the main facts of the experiment.
- Pupils are able to recall the main facts about the pineapple plant and pineapple farming.
- Pupils have a record sheet ready.
- Pupils are grouped in teams.

Lesson
(the day before the observation or immediately preceding the observations on the farm)

- Revise the reasons for setting the pineapple experiment.

- Explain the problem of the sub-unit: how can we get an answer to our question from the experiment?

- Discuss the comparison in terms of yield per hectare.

- Discuss ways to assess the yield of a pineapple farm considering the fact that fruits do not get ready for harvesting at the same time.

- Propose a record sheet and let pupils copy it into their exercise books.

- Group the pupils in teams of two or three children.

 Record Sheet Row (1) (2) (3) (4) No. Total No. of Plants Plants Harvested No. of Plants with Unripe Fruits No. of Plants without any Fruits

B. Practical Work

Objectives
- Knowing the number of plants harvested, bearing fruit, and remaining without fruits;
- pupils are able to count correctly and to record their findings correctly using the record sheet proposed in the preceding lesson.

Outdoor Activity
The teams got to their assigned rows and start counting. One team member counts, the other one enters the information in the record sheet. Team members take turns. Each team counts at least one row which has already been counted by another team. This will help cross-checking and gives an idea of the incidence of error.

When all the rows have been counted, the teacher checks a few rows himself.

C. Follow-up Lessons

1. Assembling the Observations

Objectives
- Pupils and teacher have the complete picture of all observations row by row.
- Pupils and teacher have an idea of the errors made during counting.
- Pupils know the total number of pineapples harvested and the number of fruits to be expected during the season.
- The observations are assembled in a way which permits further analysis in class.

Lesson
(immediately after the outdoor activity)

The teacher draws the observation sheet on the blackboard. The teams read out their observations starting with row 1 and going up to the last row. For each row there are at least two readings. Major differences between them give rise to a re-check on the farm. Differences of 1 or 3 plants are minor differences. Discuss possible reasons for these errors.

Teams are asked to copy the complete table of observations. The following sums are given to the teams for work:

a) For each row, add columns 2, 3, and 4. The total must agree with the entry in column 1.
b) For each of the two blocks (single row planting and double row planting), add

- the total number of plants (column 1),
- the number of plants harvested (column 2),
- the number of plants with unripe fruits (column 3),
- the number of plants without any fruits (column 4).

Data Collected by Pupils and Assembled in a Table Ready for Evaluation

 Single Row Planting (1) (2) (3) (4) Row No. No. of Plants No of Plants Harvested No. of Plants with Unripe Fruits No. of Plants without any Fruits 1 35 7 2 26 2 32 7 9 16 3 35 9 3 23 4 37 10 1 26 5 32 13 2 17 6 25 6 1 18 7 50 6 1 43 8 23 3 1 19 9 37 10 1 26 10 12 6 - 6 12 11 5 - 6 13 13 5 1 7 14 24 9 1 14 15 12 4 2 6 16 11 3 - 8 17 12 1 - 11 18 26 5 1 20 19 12 3 - 9 20 22 3 2 17 21 33 7 2 24 22 19 3 1 15 23 30 5 - 25 24 20 3 2 15 Total 585 148 34 403 Double Row Planting 25 102 34 13 55 26 95 15 3 77 27 100 25 3 72 28 106 34 3 69 29 79 14 5 60 30 86 24 2 60 31 84 25 1 58 32 95 27 8 60 33 94 30 4 60 34 42 6 6 30 35 42 19 1 22 36 42 13 4 25 37 38 11 - 27 38 44 14 - 30 39 34 10 5 19 40 43 12 13 18 41 42 14 2 26 Total 1168 327 77 768 Grand Total 1753 475 107 1171

2. The Yield in Single Row Planting

Objectives
- Pupils know the yield of the single row block in terms of fruits per hectare.
- Pupils know how to calculate this yield using the information available.

Lesson
- Get the following data for the single row block:

the total number of plants (from the table of observation),
the planting distance (from the farm records or from measurements to be done by a few pupils).

- Calculate the area occupied by each plant. It is the planting distance squared: 1.8 m x 1.8 m = 3.24 m².

- Calculate the total area of the single row block (in m² ): total number of plants x area per plant; 585 x 3.24 m² = 1895.40 m².

Note: If the area for the two blocks has been carefully measured at planting, this information can be taken directly from the records.

- Get the total number of pineapples harvested on the single row block from the table of observations.

- Calculate the number of pineapples per hectare: (total number of pineapples harvested x 10 000): total area of single row block; (148 x 10000): 1895.40 m² = 781.

3. The Yield in Double Row Planting

Objectives
- Pupils know the yield of the double row block in terms of fruits per hectare.
- Pupils know how to calculate this yield.
- Pupils know how to calculate the area per plant in double row planting.

Lesson
- Pupils are asked to calculate the yield per hectare in double row planting using the same procedure as in the preceding lesson. They will need some help in calculating the area of the double row block if this area has not been recorded in the farm records. The planting distance in double row planting is as follows: between the double rows, the distance from the centre of one double row to the next is 2.4 m. Each plant can use half that distance, 1.2 m. Along the rows, the distance is 60 cm. Each plant therefore occupies an area of 1.2 m x 0.6 m = 0.72 m² (see the illustration p. 111 for an example).

- Let the teams-work through the problem after they know the area per plant and repeat the calculations for the whole class.

Total area of the double row block = number of plants x area of double row block/ plant; 1168 x 0.72 m² = 840.96 m².

Yield per hectare = (327 x 10000 m²): 840.96 m² = 3 888.

4. Comparison Between Single and Double Row Planting

Objectives
- Pupils are able to draw conclusions from comparisons.
- Pupils are able to put conclusions in writing.

Lesson

- The teacher asks the class to compare the yields from the two blocks. He/she draws a simple table on the blackboard (see below) and asks what information should be used for comparison.

- Let the teams read out their observations and remarks and arrive at a common text.

- Ask teams to think about reasons why the double row block, where pineapples are "choked up", does not have the same or a lower yield than the single row block where pineapples have much more space.

- Ask for reasons why the yield per area in double row planting is even higher than in single row planting.

- Discuss the reasons advanced by the teams and arrive at a common summary.

 Method of Planting Single Row Double Row Fruits Harvested on each Block 148 327 Fruits per Hectare 781 3888 Planting Distance 1.8 m x 1.8 m 1.2 m x 0.6 m Area per Plant 3.24 m² 0.72 m² Plant Population per Hectare 3086 13888

5. Expected Yields at the End of the Season

Objectives
- Pupils know how to make short term forecasts and to justify them.

Lesson
- The teacher puts the following problem to the pupils: "So far, only the pineapples harvested have been counted in the yield. Is this reasonable? How can we take the unripe fruits into account?" - We do not know when the unripe fruits will get ripe.

Can we make an assumption? Assume that all fruits will get ready by the end of the current pineapple season. We can now estimate the total yield of the first season:

 single row planting: harvested 148 unripe 34 total 182 double row planting: harvested 327 unripe 73 total 400

- Ask the class to do the calculations on yield with the total number of fruits instead of the number of fruits harvested. All other figures remain the same. The results should be: single row planting: 960 fruits per hectare; double row planting 4 756 fruits per hectare.

- Ask the pupils whether the result of the preceding lesson concerning the difference between the planting methods is confirmed, whether the difference has narrowed down or grown bigger. This can be seen by asking how much bigger the double row harvest is than the single row harvest The way to do it is by a division:

double row yield/single row yield = 3888/781 = 4.97(harvested fruits) and 4756/960 = 4.95

There is a very slight difference only which can be neglected. For both yield estimates the yield in double row planting is nearly five times bigger than the yield in single row planting.

6. The Profitability of the two Planting Methods

Objectives
- Pupils know how to do a simple calculation of profit.
- Pupils can draw conclusions from two different ways of evaluating the experiment: yield in terms of fruit, and cash income.

Lesson

- Confront pupils with the question whether the class has made any profit on pineapple farming.
- Discuss the notion of profit: income - costs = profit or loss.
- From the sales records tell the class the total income from the pineapples. If a large number of fruits have been given out free, calculate their cash value. In order to do this, work out the average price per fruit sold and multiply the total number of fruits harvested by the average price.

Up to the date of evaluating the experiment, 259 pineapples had been sold, yielding an income of 14340 frs CFA. The average price per pineapple therefore was 14340 frs: 259 = 55.37 frs CFA.The cash value of the harvest in the two blocks is:

 single row planting harvested fruits 148 cash value 8195 double row planting harvested fruits 327 cash value 18106

- Ask the class what counts as cost. Argue that only suckers should be counted since the farm land and teacher's and pupils' labour were actually free.

- Calculate the average cost of the suckers. Consider that 1 800 suckers were bought at 11 500 frs CFA, but that only 1 753 of them survived. Since only the surviving plants produce a fruit, they alone can be charged with the total cost of the farm. The average cost per sucker therefore is 11 500 frs CFA: 1 753 plants = 6.56 frs CFA/plant

- Ask teams to calculate the cost of the two blocks separately. This is done by multiplying the number of plants in each of them by the average cost per plant:

 single row planting total number of plants 585 cost 3838 frs CFA double row planting total number of plants 1168 cost 7662 frs CFA

Let the class calculate the profit of the two blocks:

 single row planting cash value 8195 frs CFA cost 3838 frs CFA profit 4357 frs CFA double row planting cash value 18106 frs CFA cost 7662 frs CFA profit 10444 frs CFA

The profit from double row planting is much higher than that from single row planting.

- Ask the class to divide the income by the costs. What does the result mean? It says by how much the income has multiplied, the costs, i.e. the money invested. The results should be: single row planting: 2.14; double row planting: 2.36.

Costs for planting material have been recovered with the two planting methods. But in single planting, the yield valued in monetary terms is about 2.1 times the cost, whereas in double row planting, it is about 2.3 times the cost. Therefore, double planting is advantageous.

7. Drawing Conclusions from the Experiment

Objectives
- Pupils draw conclusions from the experiment.

Lesson
- Ask pupils what they would recommend a farmer to do if he or she planned to farm pineapples.
- Let them repeat all the results:
- Double row planting uses the soil more efficiently.

Double row planting produces yields per hectare which are five times higher than in single row planting.

Double row planting means higher cost per hectare.

Double row planting means much higher income per hectare.

Farmers should always do double row planting and use the remaining land for other crops.