1 Fig. 1.1 shows the results of a ribbon test carried out on two soil samples, P and Q, collected from different parts of a farm. (a) State what is meant by...

Labelled answer diagram:

(a) Meaning of soil texture [1]

Soil texture refers to the relative proportion of different-sized mineral particles - sand, silt, and clay - in a soil sample. [1] It determines many of the soil's physical properties including drainage, water-holding capacity, and workability.

(b)(i) Soil type of sample P [1]

Clay (clay soil). [1] The ribbon test produces a long, smooth ribbon from clay soil because the tiny, flat particles stick together when moist and can be moulded without breaking.

(b)(ii) Soil type of sample Q [1]

Sandy (sandy soil). [1] Sandy soil produces a ribbon that breaks apart quickly and feels gritty because the large, rounded particles do not bind together well.

(c) Why sample Q drains faster than sample P [2]

1. Sandy soil (Q) has larger particles with bigger pore spaces (macropores) between them. [1]
2. Water moves through these large pore spaces quickly under gravity, draining freely. In contrast, clay soil (P) has tiny particles with narrow pore spaces that hold water tightly by capillary forces, so drainage is very slow. [1]

(d) Which sample is more suitable for rice, and why [2]

Sample P (clay soil) is more suitable. [1] Rice (paddy rice) is grown in flooded fields and requires the soil to retain standing water. Clay soil holds water well because its small particles and narrow pores resist drainage, maintaining the waterlogged conditions that rice needs for healthy growth. [1]

(e) One way to improve water-holding ability of sample Q [1]

Add organic matter (compost, manure, or humus) to the sandy soil. [1] Organic matter acts like a sponge, absorbing and retaining moisture in the large pore spaces between sand grains. Adding clay to the sandy soil is also acceptable.