The development of techniques of assessing soil compactability

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dc.contributor.advisorSpoor, Gordon
dc.contributor.authorEarl, Richard
dc.date.accessioned2023-01-26T14:17:58Z
dc.date.available2023-01-26T14:17:58Z
dc.date.issued1993-06
dc.description.abstractThe recent decline in farming profits has prompted an urgent need to increase efficiency, either by increasing outputs or reducing the cost of inputs. Soil compaction can influence adversely all stages of crop development, and hence yield, and is expensive to ameliorate in terms of time taken and power required. Minimum cultivation or direct drill crop establishment systems can reduce inputs, however, they are very susceptible to compaction from the previous season. There is a need to develop a greater understanding of the compactive nature of soil, and hence trafficability and workability, in relation to the selection of appropriate machinery to carry out agricultural operations. A study of research on soil compaction revealed that the majority of work to date has been carried out using disturbed soil samples in laboratory situations. The aim of this project is to develop techniques and models, based on field data, for assessing the susceptibility of soils to compaction by agricultural machinery. Work, conducted during this study, was carried out in the field in a range of soils, crops and climatic conditions. The study was approached by dividing the project into two sections:- (1) Prediction of trafficability and workability on a go/no-go basis. Soil water suction (h), soil moisture deficit (SMD) and cone penetration resistance were monitored at six field sites, under grass and an arable crop, covering a range of agricultural situations commonly found in central and eastern England. Strong correlations were found to occur between both h and SMD and:- (a) a qualitative assessment of soil condition, and (b) cone penetration resistance. These data formed the basis of models for predicting trafficability and workability at a given site on a particular day, and at any 5km square in England and Wales as an aid to business planning. (2) Assessment of the compactive nature of soil during loading. A methodology was developed which provides a measure of the susceptibility of soil to damage if land is trafficked when in an unsuitable condition. It is based on results of plate sinkage tests, in conjunction with those from confined compression tests, performed in the field using tractor-mounted equipment. Soil behaviour during compression was found to be governed by three phases:- (a) compaction with uniform lateral stress, (b) compaction with increasing lateral stress, and (c) displacement of soil laterally. Mathematical models are presented for predicting, for a given load and soil, the deformation phase and extent of disturbance likely to occur. The prediction models developed during this study provide a new approach to the selection of, and assessment of damage by, agricultural machinery.en_UK
dc.description.coursenamePhDen_UK
dc.identifier.urihttps://dspace.lib.cranfield.ac.uk/handle/1826/19025
dc.language.isoenen_UK
dc.rights© Cranfield University, 2015. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
dc.titleThe development of techniques of assessing soil compactabilityen_UK
dc.typeThesisen_UK

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PhD, EngD, DM and MSc by research theses (Silsoe)