Abstract :
Alpacas establish long-lasting communal latrine sites or dunghills. To quantify the extent
of nutrient transfer and accumulation associated with alpaca latrine sites and to provide
a three-dimensional assessment of a pasture paddock with 11-year-old latrine sites,
three comparisons were made: (a) centres of latrines were compared with non-latrine
control sites 20m away; (b) surface soils (0–10 cm) were compared with subsurface soils
(10–30 cm); and (c) across cardinal compass directions and regular distances from latrine
centres were compared. Accumulation of nutrients was clearly detected, with a significant
surface build-up, relative to controls, observed in phosphorus (3 times), nitrate-nitrogen
(3.8 times), potassium (3.2 times), sulfur (1.9 times), organic carbon (1.3 times) and electrical
conductivity (2.4 times). Soil pH was also significantly decreased in the centre of the
latrine sites (pHw 0.6–0.7 units). Across the main axes of the latrines there was a clear trend
of decreasing electrical conductivity, organic carbon and nutrients (NO3, P, K, Ca, Mg, Na,
and S) away from a peak concentration at or near the centre. Soil pH demonstrated the
inverse with a decrease towards the centre. Under set stocking conditions large transfers in
nutrients towards latrines could have long-term effects on pasture growth and composition.
Some management options are discussed.
