Feral Goats

Land and Catchment Management Field Trip Report

Elizabeth McCrudden

U5026733

Claypans and Waterponding

Claypans are bare and scalded areas in the semi-arid rangelands in Australia. Claypans are areas of land which have been scalded by wind erosion removing their top soil. In the rangelands in NSW the soils are largely a duplex soil with a sandy clay loam top soil and a clayey subsoil (Thompson, 2008). The high levels of wind erosion are due to the dramatic landscape modification which has occurred since European settlement. Land clearing and overgrazing have reduced native vegetation and allowed for the sandy loam top soil to be removed, leaving impermeable subsoil. The thin crust which forms on the surface prevents water from seeping in, resulting in low or no vegetation colonization (see Figure 1). This subsequently leads to more erosion through water runoff at a high velocity (Thompson, 2008).

Figure 1. Claypan crusted surface

There have been various methods employed to try and overcome this issue. These have included disturbing the clay pans using ploughs, furrows in the patterns of checkerboards and spirals. Tyne pitting and complete ploughing has also been used unsuccessfully (Thompson, 2008). The vegetation would only grow back in the narrow furrows, if at all. The idea of waterponding stemmed from observing vegetation regeneration in tank and roadside drains.

Waterponding has now been used for over 20 years in Western NSW and creates complete vegetation cover over the treated areas (Quilty, 2004). A waterpond is either a horse shoe shaped or an enclosed circle depending on the slope of the landscape. They reply on the rain to fall onto the landscape directly into the pond or to runoff into the horse shoe shaped pond. The maximum recommended storage of a single pond is half a hectare with a bank length of 200- 300 meters. The maximum depth should be 10cm as any deeper would damage native grasses and shift vegetation type to more wetland...