why there is more bounce, pace and seam movement in a pitch with grass?

Question

In cricket fast bowlers favour pitches with grass as it gives moe pace and lateral mvement. What is the science?

Answer 1

The reason behind more swing and pace when the pitch is green and grassy, the ball tends to retain its sheen much longer ,in other words its surface is still smooth and hence enabling it to cut through air friction more easily(which result in a swing in air).

And the weight of the ball is sufficient to crush some of the tender green grass shoots. This contact with grass and earth sometimes produces a trace of moisture(present in grass) to aid the pace of the ball resulting in increase in pace as ball is not gripping the surface and hence not losing its pace(a bit of moisture makes the ball skidding) and, according to the direction or angle of the seam of the ball when it lands, the direction of its flight be very slightly deviated due to contact and breaking of grass shoots(which we call seam).

The grass roots hold the soil firmly to each other, hence the pitch doesn't loosen up maintaining its hardness which helps the ball to bounce more.

Answer 2

pitch well covered with grass and with some green grass on the surface when play starts (although not all would agree with the need for surface green grass). The evenness of the grass turf is particularly important since patchy grass will cause patchy drying and areas which are not occupied by grass will crack excessively at the surface but remain moist at depth (because there are no roots to pump out the water)

so if the ball lands the there is a great bounce

Answer 3

Swing; A lot depends on the density of air. The denser the air, more resistance, and more swing. The grass helps in retaining a bit of moisture in the air and encourages swing.

Bounce: The grass reduces the friction where the ball hits the pitch. So it deacclerates a lot less and apparently there is a lot more pace.

Seam movement: The grass helps the ball to grip on the surface. And as grass is uneven, there is more chance of ball deviating after hitting the surface.

Answer 4

The grass at the surface shows there are living roots below, these hold the pitch together more so mean that the ball retains more pace when bouncing

Answer 5

grass holds the pitch hard and when the seam hits dry grass it deviates more.both these are helping fast bowlers to extract bounce and pace.

Answer 6

because of cracks