Neco 2022 Agricultural Science Question 2

A laboratory experiment was performed to determine the water‑holding characteristics of three soil types (A, B and C). For each soil, a 100 g oven‑dry sample was taken and the following weights were recorded: - Saturated weight (after submerging the sample and allowing excess water to drain) - Field‑capacity weight (after allowing the sample to drain for 24 h at room temperature) - Wilting‑point weight (after further drying the sample in a controlled environment until the moisture content corresponds to the permanent wilting point). The bulk densities of the soils are given. | Soil | Bulk density (g cm⁻³) | Saturated weight (g) | Field‑capacity weight (g) | Wilting‑point weight (g) | |------|----------------------|----------------------|---------------------------|--------------------------| | A | 1.30 | 180 | 130 | 115 | | B | 1.45 | 170 | 140 | 120 | | C | 1.20 | 190 | 150 | 130 | Using the data, answer the following: (a) Calculate the volumetric water content at field capacity (θ_fc) for each soil (expressed as a percentage). (b) Calculate the volumetric water content at the permanent wilting point (θ_wp) for each soil (percentage). (c) Determine the available water capacity (AWC = θ_fc – θ_wp) for each soil and identify which soil has the highest AWC. (d) A crop requiring a minimum of 25 % available water is to be cultivated. Recommend the most suitable soil(s) and justify your choice.