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Minimising Compaction in a Shallow Cultivation System

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Minimising Compaction in a Shallow Cultivation System CRANFIELD UNIVERSITY W.C.T. CHAMEN THE EFFECTS OF LOW AND CONTROLLED TRAFFIC SYSTEMS ON SOIL PHYSICAL PROPERTIES, YIELDS AND THE PROFITABILITY OF CEREAL CROPS ON A RANGE OF SOIL TYPES SCHOOL OF APPLIED SCIENCES PhD THESIS Academic year: 2010-2011 Supervisors: Dr A.M. Mouazen Prof R.J. Godwin April 2011 CRANFIELD UNIVERSITY SCHOOL OF APPLIED SCIENCES PhD THESIS Academic year: 2010-2011 W.C.T. CHAMEN The effects of low and controlled traffic systems on soil physical properties, yields and the profitability of cereal crops on a range of soil types Supervisors: Dr A.M. Mouazen Prof R.J. Godwin April 2011 This thesis is submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy © Cranfield University 2011. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner. Abstract Soil compaction is an inevitable consequence of mechanised farming systems whose machines are degrading soils to the extent that some are considered uneconomic to repair. A number of mitigating actions have been proposed but their ability to reduce or avoid damage has not been well tested. The aim of this research was to determine whether actions to reduce damage have been, or are likely to be effective and to assess whether the practice of controlled traffic farming (confining all field vehicles to the least possible area of permanent traffic lanes) has the potential to be a practical and cost effective means of avoidance. The literature confirmed that soil compaction from field vehicles had negative consequences for practically every aspect of crop production. It increases the energy needed to establish crops, compromises seedbed quality and crop yield, and leads to accelerated water run-off, erosion and soil loss. It is also implicated in enhanced emissions of nitrous oxide and reduced water and nutrient use efficiency. Replicated field trials showed that compaction is created by a combination of loading and contact pressure. Trafficking increased soil penetration resistance by 47% and bulk density by 15% while reducing wheat yield by up to 16%, soil porosity by 10% and infiltration by a factor of four. Low ground pressure systems were a reasonable means of compaction mitigation but were constrained due to their negative impact on topsoils and gradual degradation of subsoils whose repair by deep soil loosening is expensive and short lived. Controlled traffic farming (CTF) was found to be practical and had fundamental advantages in maintaining all aspects of good soil structure with lowered inputs of energy and time. On a farm in central England, machinery investment with CTF fell by over 20% and farm gross margin increased in the range 8-17%. ACKNOWLEDGEMENTS First and foremost I would like to thank my wife Chris without whose unstinting support, patience, good counselling and many hours spent helping me in the field, I would not have been able to complete this work. I am also most grateful to Dr Abdul Mouazen and Professor Dick Godwin, my supervisors at Cranfield University, whose reviews of my work and thesis have been invaluable and have kept me focused. In relation to Chapter 5, I would also like to acknowledge the financial support of the Douglas Bomford Trust, the Chadacre Trust and the Morley Foundation for carrying out the research. Acknowledged also is the input of Jo Philpott who initiated and applied the treatments in the first year some of whose words I have used in the Introduction to Chapter 5. Thanks also go to F.B. Parrish and Sons and to Unilever R&D Colworth for the use of their land and facilities and to Simba International for their loan of a cultivator. I would also like to thank Richard Long, Whitbread Farms Ltd and L.E. Barnes and Son for the loan of equipment and drivers. Table of Contents The effects of low and controlled traffic systems on soil physical properties, yields and the profitability of cereal crops on a range of soil types ................................................ 2 Abstract .................................................................................................................................. 3 ACKNOWLEDGEMENTS ....................................................................................................... 4 Table of Contents ................................................................................................................... 5 Figures ........................................................................................................................... 10 CHAPTER 1 .............................................................................................................................. 1 1.1. Introduction ................................................................................................................. 1 1.2. Aim ............................................................................................................................... 5 1.3. Specific objectives related to the hypotheses ............................................................. 6 1.4. Outline methodology ................................................................................................... 7 CHAPTER 2 .............................................................................................................................. 8 2. Literature review ................................................................................................................ 8 2.1. Introduction ................................................................................................................. 8 2.2. The global soil resource ............................................................................................... 9 2.2.1. Global Agro-eco Zones study ................................................................................ 9 2.2.2. Soil degradation and threats to the environment .............................................. 10 2.3. Conservation agriculture ........................................................................................... 11 2.4. Reviews on the effects of soil compaction in agriculture .......................................... 13 2.4.1. Soil physical aspects ............................................................................................ 14 2.4.2. Crop nutrients ..................................................................................................... 19 2.4.3. Soil biology .......................................................................................................... 19 2.4.4. Discussion of reviews on the effects of soil compaction in agriculture .............. 21 2.5. Soil structure .............................................................................................................. 22 2.5.1. Soil organic matter and nitrous oxide ................................................................. 22 2.5.2. Seedbed quality ................................................................................................... 25 2.5.3. Soil strength and bulk density ............................................................................. 26 2.5.4. Pore space, water holding capacity, infiltration and drainage characteristics ... 32 2.6. Crop production efficiency ........................................................................................ 39 2.6.1. Crop responses .................................................................................................... 39 2.6.2. Fertiliser use efficiency........................................................................................ 45 2.6.3. Vehicle and implement performance ................................................................. 48 2.7. Controlled traffic farming systems ............................................................................ 51 2.7.1. Economics of conversion to and maintenance of controlled traffic farming systems .......................................................................................................................... 51 2.7.2. Practical aspects of CTF systems ......................................................................... 55 2.8. Conclusions to the literature review ......................................................................... 65 2.9. Gaps in research......................................................................................................... 67 CHAPTER 3 ............................................................................................................................ 69 3. Papers published by the author addressing the principal hypothesis ............................. 69 3.1. Introduction ............................................................................................................... 69 3.2. Methodologies ........................................................................................................... 69 3.3. Discussion of papers .................................................................................................. 70 3.3.1. Chamen et al., 1990. The effect of tyre soil contact pressure and zero traffic on soil and crop responses when growing winter wheat .................................................. 70 3.3.2. Chamen et al., 1992a. Assessment of a wide span vehicle (gantry), and soil and crop responses to its use in a zero traffic regime ......................................................... 93 3.3.3. Chamen & Longstaff, 1995. Traffic and tillage effects on soil conditions and crop growth on a swelling
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