Abstract:
In the game of cricket, where a ball is bounced on a natural clay soil pitch between the
‘bowler’ and ‘batsman’, the ball-surface interaction is critical and is one of the most
important factors responsible for the quality of play. Rolling of the playing surface with
a smooth-wheel roller is common practice and this is intended to encourage pace, but
with a predictable ball bounce that will provide a fair and safe playing surface.
Current rolling management is largely based on anecdotal evidence and little work has
previously being carried out in the UK to quantify the effects of rolling on cricket soils
or to determine optimum rolling practice. Initiatives by the England and Wales Cricket
Board (the project sponsors) to advance the commercial viability of the game of cricket
and to increase player participation provide commercial justification for this project.
This thesis aims to improve the fundamental understanding of the scientific principles
of pitch preparation and to develop practical guidelines on roller use to help cricket
groundsmen produce playing surfaces with the desired playability characteristics.
A diverse methodology was used to meet the project objectives. A survey of current
practice was conducted to inform experimental design and inform the targeting of
rolling guidelines. Dynamic and static triaxial experiments were combined with
standard laboratory tests to establish soil mechanical parameters for cricket soils. Field
experimental plots and a project designed rolling simulator were used to investigate the
interaction between soil mechanical and roller physical properties and to establish
rolling management protocols. A grass rooting experiment was also conducted to
determine the effect of soil density on root growth and distribution within the
compacted soil profile.
The survey of current practice established a wide range in rolling practice, particularly
in the time allocated to rolling in the spring and for summer pre-match rolling. The
experimental results developed the relationship between moisture and soil mechanical
properties of cricket soils indicating an increase in plastic and elastic strain with an
increase in moisture in un-saturated soils. An increase in soil moisture from 16% to
25% gravimetric moisture content was also shown to increase horizontal movement
under a towed roller; however the inclusion of grass roots into the soil profile considerably reduced soil displacement. Soil optimum moisture conditions were
identified for a range of roller specifications; 24% gravimetric moisture for a 750 kg m
-3
roller and 22% for a 920 kg m
-3
roller. Roller speed (0.7 km h
-1
) and the amount of
roller passes required (four passes of a two drum roller in the spring and a total of 10
passes for summer match preparation) were established for cricket pitch preparation.
Results also indicated a significant potential to reduce annual rolling times when
undertaken in optimum soil moisture conditions. This could result in a substantial
reduction in cost to the cricket industry and a reduction in CO2 emissions.