The shape and size of any farmland can be measured or determined by farm surveying. The area of farmland varies; some are rectangular, square, triangular or even circular in shape. The formula used in the calculation of farmlands and plant population include:

**a) Area of Farmland:** This refers to the product of the length and width of the farmland measured in metres. Mathematically,

Area of farmland = Length x Width (metres)**/**(L x W)m

**b) Number of Plant Stand/Plant Population:** This refers to the number of plants in an area of farmland. Mathematically,

Plant population= Area of farmland (m2)/Spacing (m3)

**c) Spacing:** This is the distance between one crop plant and the next plant which is usually between and within the rows, e.g ., 60cm x 30 and 100cm x 75cm.

**d) One hectare = 10,000m2**. This figure means there are 10,000m2 in one hectare of farmland. This figure is always used when the area of farmland is given in hectare.

**e) Measuring the Area of Farmland:** The shape and size of any farmland can be measured or determined by farm surveying. The area of farmland varies as already noted above.

**Formulae for calculating the area of farmland are shown below.**

**Example 1:** If the length and width of a farmland are 60m x 30m respectively, and the spacing of a tomato crop plant is 30cm x 30cm, calculate:

- the area of the farmland;
- the plant population (tomato) in the given area;
- the total population if there are two plants per stand.

20,000 x 2 = 40,000 tomato plants

The total population = 40,000 tomato plants.

**Example 2**

A school farm in Lagos State was surveyed and presented in a map. Use it to answer the following questions.

- What is the approximate area of the farm?
- If the farmland is used for pineapple production at a spacing of 2.5mx 2m, what will be the initial population of pineapple trees in the farm?
- If 8% of the pineapple plants were damaged by pests, what will be the final pineapple plants in the farm?

Note: The longest portion of the farm is 70m long.

**Example 3**

- A piece of land to be used to establish a pasture of
*Stylosanthes gracilis*was surveyed to be circular. - If the radius of the land is 200m and the spacing of the pasture legume is 1 m by 50cm, what is the population of the legume at one seed per stand?
- If the germination percentage is 75, calculate the expected plant population.