Temporal trends in soil physical properties under cropping with intensive till and no-till management

ABSTRACT

Improved process understanding of temporal change in soil hydraulic, water retention, and soil physical properties is required to improve modelling of soil-water dynamics. This study reports on temporal trends in soil physical properties for intensive till and no till irrigated wheat, from autumn sowing to summer harvest. There were significant temporal trends for bulk density, readily available water capacity, and unsaturated hydraulic conductivity (at three matric potentials). Using a simple two-parameter exponential model for unsaturated hydraulic conductivity, the model coefficients appeared to increase over the first 10 weeks, followed by a decrease and later increase, but the temporal effect when using this model was not significant given the parameter uncertainty. Daily rainfall, irrigation, and evapotranspiration were evaluated as possible explanatory variables, but these were not generally significant in explaining temporal trends of soil properties. An implication is the need to provide temporal data to parameterise hydrological models for more accurate modelling, including irrigation scheduling.

KEYWORDS:

• Soil water release
• soil water retention
• hydraulic conductivity
• soil compaction
• tillage

Acknowledgements

We thank the Foundation for Arable Research (FAR) for use of the Chertsey Arable Research Site, and Abie Horrocks for providing site information, John Dando from Manaaki Whenua – Landcare Research for soil physical laboratory analyses, and Craig Tregurtha from Plant and Food Research for soil quality data. Comments from several reviewers improved the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Principal funding was provided by the New Zealand Ministry of Business, Innovation and Employment for the Manaaki Whenua – Landcare Research and Plant and Food Research led programme, Maximising the Value of Irrigation, (contract CO9X1309). Co-funding was provided from the Foundation for Arable Research, Horticulture New Zealand, Environment Canterbury, Hawke’s Bay Regional Council and Irrigation New Zealand.