There was no obvious pattern in surface soil water between treatments, although it did change in consistent ways between measurements (Table 2). Soil water in the root zone (10-70cm) tended to be higher in the ‘Till’ paddocks following cereal crops in northern paddocks after the drought year of 2006 (Table 3). This probably reflects generally higher clay content in these paddocks. A similar pattern in all paddocks at harvest in 2007 reflected fallow at Sea Lake and Donald, and Chickpea crops at Yaapeet and Minyip No-Till paddocks (late-season water use). It is difficult to interpret changes in water content during summer fallow without also looking at rainfall patterns (and differences between widely spaced paddocks) but, apart from textural differences, some farmers seem to be able to make better use of fallow rainfall in 2006 (eg. Yaapeet Till and Minyip No-Till). Differences in 2007 need to be interpreted with consideration of fallows in 2007.

The “subsoil” depth (70-100cm) was less regularly sampled at some sites because of dry soil – this indicates the state of the subsoil where a sample is missing! The same pattern of more water (clay) is present in the northern paddocks as in the southern ones (Table 4). Notable features at this depth are the relative lack of water use at Culgoa and substantial water use in the Donald ‘Till’ paddock during the 2006 crop. Most paddocks gain water at this depth in 2006/7 fallow except at Culgoa, but there is little water use in 2007 crop except at Minyip. There is substantial water loss during the 2007/8 fallow at Yaapeet and the Patchewollock Till paddock (no record for the No-Till paddock), probably reflecting ‘draw up’ from the layer above.   

Table 2. Soil water 0-10cm and change in soil water during the crop (Harvest – Sowing) and fallow (Sowing – previous year Harvest) periods.

Table 3. Soil water 10-70cm and change in soil water during the crop (Harvest – Sowing) and fallow (Sowing – previous year Harvest) periods.

Table 4. Soil water 70-100cm and change in soil water during the crop (Harvest – Sowing) and fallow (Sowing – previous year Harvest) periods.