Michael Braunack1, Darin Hodgson1
1 CSIRO Agriculture & Food, LMB 59 Narrabri, NSW, 2390, www.csiro.au, firstname.lastname@example.org
Soil sodicity, acidity and formation of hardpans have been identified as constraints to productivity on the western plains, NSW. Information is available on the identification, cost of the constraint and potential management strategies. Surface crusting was identified as a constraint limiting the infiltration of rainfall reducing the opportunity to store water during the fallow. A field experiment was established near Nyngan to examine the effect of current farm practice and surface applied gypsum (2.5 t/ha) along with deep tillage +/- gypsum on profile water storage during a fallow period and two crop cycles. Water storage in the 120-cm profile was the same for current practice and the gypsum treatment and significantly lower for the tillage (20 cm) +/- gypsum throughout the two cropping seasons (Chickpea followed by wheat): 127, 123, 75 and 111 mm of water for the control, surface gypsum, tillage and tillage + gypsum, respectively. There were no significant differences in yield, water use or crop water-use efficiency between treatments for both crops. Gross margin analysis showed a loss for all treatments in the first season and a small profit for the second season. The benefit of the treatments need to be assessed over several seasons due to variability between growing seasons.