New Zealand Journal of Agricultural Research abstracts

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Impact of cattle treading on hill land
2. Soil physical properties and contaminant runoff

M. L. NGUYEN
National Institute of Water & Atmospheric Research Ltd
P. O. Box 11-115
Hamilton, New Zealand

G. W. SHEATH
AgResearch
Ruakura Agricultural Research Centre
Private Bag 3123
Hamilton, New Zealand

C. M. SMITH*
A. B. COOPER
National Institute of Water & Atmospheric Research Ltd
P. O. Box 11-115
Hamilton, New Zealand

*Present address: Landcare Research, Private Bag 3127, Hamilton, New Zealand.

Abstract  A simulated rainfall study carried out as part of a larger grazing experiment was conducted to investigate the effects of a 2-3 day cattle-treading event in winter on soil physical properties and contaminant (sediment and nutrient) runoff in topographically variable hill land. Measurements were made on two land zones: easy contoured ridges and gullies (15-24deg. slope) and steep inter-track land (28-39deg. slope). Simulated rainfall was applied to 16 plots (0.5 m²) with a range of treading damage for each land zone within 14 days of the treading event. Simulated rainfall was repeated on the same plots in the following summer and winter to assess the recovery of soil from treading damage.

Treading damage reduced water infiltration rate, particularly in the steep zone. It also caused a significant increase in the transport of suspended solids (SS), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) from the plots during simulated runoff. On the steep inter-track zone, damaged areas had a 46% lower infiltration rate, and runoff from these areas contained on average 87% more sediment, and 89% more N and 94% more P compared with undamaged areas. These effects had disappeared six months later. The rainfall simulation and soil physical studies show that a 2-3 day winter treading event may increase soil bulk density, reduce soil macroporosity and total porosity, and lead to a decrease in the water infiltration rate and an increase in contaminant runoff.

Keywords  treading; cattle; water runoff; water quality; sediment; grazing management; hill land

New Zealand Journal of Agricultural Research, 1998, Vol. 41: 279-290

0028-8233/98/4102-0279 $7.00/0 (c) The Royal Society of New Zealand 1998

PDF file of entire paper: medium quality (988K); (scanned from paper original: notes about this process)

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