The ribbon test is performed by working in the hand a very wet clump of soil slightly larger than a golf ball. The soil should be kneaded until it has fairly uniform wetness throughout. Ribbons are formed by working the ball of soil in the palm up through the thumb and forefinger. Soil is loose and single grained. Soil structure refers to the way the soil aggregates, particles, and pore space are arranged with respect to each other.
Soil scientists use shape, size, and strength to define it.
Platy, block, granular, subangular blocky are some terms associated with soil structure. Structure, or even lack of structure, has several possible ways of affecting plant growth. It affects air exchange with the atmosphere, the speed of water movement into and through the soil, it influences the quantity and size of pores, and the rate and extent of root growth. Structure may be altered through management. Organic matter and clay minerals are the primary agents for binding soil particles together to form aggregates.