Effect of tillage practice on grain sorghum production in northern New South Wales

Abstract

Grain sorghum was sown at 5 sites in northern New South Wales to examine the response of this crop to no-tillage compared with cultivated fallows. The sites were at Duri and Tamworth in 1980-81, and Warialda, Croppa Creek and Burren Junction in 1982-83. Other treatments investigated were: rates of atrazine applied in the fallow at 4 sites, the gypsum x tillage interaction at 2 sites, and effect of stubble burning during the cultivated fallow at 2 sites.

An average of 31 mm more water was stored in the soil with a no-tillage fallow, and this was associated with a consistent grain yield advantage averaging 0.45 t/ha compared with cultivated, stubble retained fallows over all sites. At Warialda and Croppa Creek the stubble on the cultivated treatments from the 1981 wheat crop was either retained or burnt. Moisture accumulation and yield were substantially reduced in the stubble burnt treatment, particularly at Warialda. There was a yield advantage of the no-tillage treatment over the stubble burnt cultivated treatment of about 1.8 t/ha at Warialda, and 0.7 t/ha at Croppa Creek.

At Burren Junction, gypsum increased grain sorghum yield by 0.57 t/ha in both the cultivated and no-tillage treatments, indicating that it was not necessary to incorporate the gypsum to improve soil structure.

The results of this study indicate that no-tillage sorghum, using atrazine as the primary method of weed control, is an efficient method of production. Potential yield advantages of about 0.5 t/ha over cultivated fallows with stubble retained, and greater yield advantages in comparison with cultivated fallows with burnt stubble, are associated with improved moisture storage.