The effect of irrigated land-use intensification on the topsoil physical properties of a pastoral silt loam

ABSTRACT

In Canterbury, New Zealand, there has been a widespread conversion of dryland sheep grazing to more intensive irrigated dairying. We determined the effects of these land uses on soil physical properties, and water release characteristics, on adjacent sites: a centre-pivot sprinkler-irrigated dairy farm site, a dryland sheep site, and a non-grazed, non-irrigated control site. Despite the Pallic Soil being well drained, greater soil compaction occurred at the dairy site than at other sites, to at least 30 cm depth. The dairy site typically had significantly lower total porosity and macroporosity, and greater bulk density and volumetric water content, than the other sites. Available water capacity varied but was greater at the dairy site (0–30 cm) than at the sheep site and control site. Further research is required across more farms and soils to confirm these results in other conditions.

KEYWORDS:

• Soil physical properties
• macroporosity
• water-holding capacity
• soil quality
• compaction
• intensification

Acknowledgements

The authors would like to thank the Lincoln University Dairy Farm and other farm staff for access; Neil Smith, Lincoln University; John Dando, Manaaki Whenua – Landcare Research for several soil physical analyses; Dave Saville of Saville Statistical Consulting Ltd for the statistical analyses and advice; Veronica Penny for feedback on a draft; and Ray Prebble for editing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Funding was provided by Lincoln University, Alexanders Chartered Accountants to support N. Mesman, the Manaaki Whenua – Landcare Research and Plant & Food Research-led research programme ‘Maximising the Value of Irrigation’, and for this manuscript, the Next Generation S-Map programme, funded by the New Zealand Ministry of Business, Innovation and Employment (contracts C09X1309 and CX09X162).